SECTION 1 – TURBINES - EPS

Electric Power Industry of Serbia, Belgrade Tender Documentation _____________________

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SECTION 1 – TURBINES


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CONTENT

1. TECHNICAL DESCRIPTION, REQUIREMENTS AND DATA .......................................... 4

1.1 General ................................................................................................................... 4

1.2 Technical description and data of existing equipment ................................. 4

1.3 Technical description, data and requirements for rehabilitation and modernization of equipment ....................................................................................... 10

1.4 Special gurantees for turbines ........................................................................ 15

2. SCOPE AND LIMITS OF SUPPLY ............................................................................... 23

2.1 General ................................................................................................................. 23

2.2 Turbine model tests, .......................................................................................... 23

2.3 Dismantling and transport of existing equipment, ...................................... 23

2.4 Design (as per Point 1.3.3) and manufacturing of the following turbine equipment: ...................................................................................................................... 23

2.5 Design and manufacturing of the pressure relief equipment: ................... 23

2.6 Spear parts .......................................................................................................... 24

2.7 Transport of new equipment, ........................................................................... 24

2.8 Installation of new equipment.......................................................................... 24

2.9 Tests and commissioning of new equipment ............................................... 24

2.10 Obligations during Defect notification period .......................................... 24

2.11 Miscellaneous .................................................................................................. 24

3. DOCUMENTATION ........................................................................................................ 26

3.1 General ................................................................................................................. 26

3.2 Documentation to be Submitted with the Bid ................................................... 26

4. DISMANTLING AND INSTALLATION REQUIREMENTS .......................................... 30

4.1 General ................................................................................................................. 30

4.2 Spiral case and stay vanes ............................................................................... 30

4.3 Installation of removable turbine parts .......................................................... 31

5. DESIGN, MATERIAL AND WORKMANSHIP .............................................................. 32

5.1 General ................................................................................................................. 32

5.2 Design and manufacturing tolerances ........................................................... 33


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5.3 Design stresses .................................................................................................. 33

5.4 Materials............................................................................................................... 33

5.5 Welding of structures under water pressure ................................................ 35

5.6 Corrosion protection ......................................................................................... 36

6. SPECIFIC REQUIREMENTS FOR PARTS .................................................................. 37

6.1 Turbine ................................................................................................................. 37

6.2 Wearing Rings .................................................................................................... 38

6.3 Turbine and middle shaft .................................................................................. 38

6.4 Turbine Guide Bearing ...................................................................................... 39

6.5 Spiral Casing and Stay Ring ............................................................................ 39

6.6 Head Cover, Bottom Ring and Discharge Ring ............................................ 40

6.7 Draft Tube Cone ................................................................................................... 40

6.8 Shaft seal ............................................................................................................. 41

6.9 Guide Vanes and Operating Mechanism ........................................................... 41

6.10 Guide Vanes Servomotors .............................................................................. 42

6.11 Overspeed measuring devices ....................................................................... 42

6.12 Control and turbine instruments ................................................................. 42

6.13 Standard and Special Tools ......................................................................... 43

6.14 Cooperation with Generator Manufacturer ................................................ 44

7. INSPECTION AND TESTS ............................................................................................ 45

7.1 Material Tests ...................................................................................................... 45

7.2 Workshop assembly and workshop tests ..................................................... 50

7.3 Model Tests ......................................................................................................... 51

7.4 Tests on Completion ......................................................................................... 54

7.5 Trial run ................................................................................................................ 56

7.6 Guaranteed tests ................................................................................................ 57

7.7 Trial Run............................................................................................................... 58


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1. TECHNICAL DESCRIPTION, REQUIREMENTS AND DATA

1.1 General

General information and technical Requirements regarding the subject Rehabilitation & Modernization Works are given in the General Technical Requirements which shall be considered as a constitutive to this Special Technical Requirements, in order of prevalence.

Subject of this Section 1 is replacement and upgrading of two (2) existing Francis turbines.

Data, information, requirements and conditions from this Section, as the “frame section” for reconstruction and rehabilitation of mechanical equipment, shall be relevant, where applicable, to other Sections of these Special Technical Requirements.

Layout and cross section drawings of the plant and main equipment, with overall dimensions and elevations are shown in the Part Drawings. These drawings are only for Tender purpose and are not considered as defining the design of the equipment, but are intended to show the general layout and space requirements. Modifications may be made to suit the design of the equipment furnished by the Contractor, if the Employer deems such modifications appropriate and acceptable.

1.2 Technical description and data of existing equipment

1.2.1 Technical description

Hydropower Plant (HPP) Bistrica is 3rd cascade of river UVAC hydropower system and the largest HPP of the Limske HPPs. HPP Bistrica is located at the right bank of river Lim. Installed output is 2x54 MW, with average yearly production of 350 GWh. In the Plant the small generating unit (serving for auxiliary power supply of Limske HPPs) of capacity 1 MVA, is installed.

The plant is a derivation type, with a compensation reservoir supplied with water from the accumulation reservoir Kokin Brod. The Radoinja dam is located on the river Uvac near the village of Radoinja, while the powerhouse of HPP "Bistrica" is located on the right bank of the river Lim directly downstream from the mouth of the Bistrica River in Lim.

The dam is made of stone embankment with upstream asphalt concrete sealing screen, on the surface of the stone layer in dry, about 35 m high with an angle of 815,0 m. The normal water level is 814.87 masl, the normal slope angle is 812.00 masl, while the minimum operating level is 805.00 m. The length of the dam in the crown is 361,00 m, and with the overflow part 400,00 m. The total body capacity of the dam is 133,000 m³.

The free spillway is a knot's shape (4 knots) with an spillway at 812.0 masl, with a capacity of 1400 m³/s (thousand-year large water).

The bottom outlet is located in a 120 m diameter tunnel and 7 m in diameter. The bottom outlet capacity at normal water level is 50 m³/s and for minimum water level 20 m³/s.

The reservoir od the dam Radoinja serves as compensation pool downstream of the HPP "Kokin Brod". In addition, it accepts by-pass waters, whose inflow is 0.9 m³/s. The total volume of the reservoir is 7.5 × 106 m³, while the useful volume of the reservoir is 4.0 × 106 m³. The length of the reservoir is 12 km along the Uvac River to the Kokin Brod HPP. The main purpose of the reservoir is the production of electricity in the HPP Bistrica, and in the last 10 years the water from the Reservoir Radoinja is flooded with water for the water supply of the city of Priboj.

The installed capacity of the hydroelectric power plant is 36.0 m³/s and 2.8 × Qsr.

The water supply system consists of an power intake, an inlet pressure tunnel, a surge tank, a surge tank valve chamber and two pressurized penstocks.

The power intake of the tunnel is located on the left bank of Uvac, directly upstream from


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the Radojnja dam. The power intake consists of an entrance funnel and gate chamber. The seal level of the ower intake is at el. 795,00 masl, while the gate house is located above the vertical shaft at an angle of 815,00 masl. At the gate location, the dimensions of the clear opening are 2.8 × 4.5 m, and behind the gate, at a length of 10 m, a passage from the rectangular to the circular cross-section of the inlet tunnel is made.

The tunnel is 4.0 m in diameter, 8.026 m in length. The tunnel drop is 2 ‰. Pressure in the tunnel ranges from 1.7 bar at the entrance to 4.6 bar at the end of the tunnel (bearing in mind the water hummer). The tunnel is with a concrete covering of MB220 35-40 cm thick at 60% of length and 45-55 cm with an inner lining of reinforced torkret 4-8 cm on the rest.

At the end of the tunnel the surge tank is located. The surge tank is of a differential type with water elevation for minimal dynamic level of 785.51 m and an angle of maximum dynamic level (overflow) of 820.20 m. The volume of the lower chamber is 1400 m³, and the upper chamber is 3000 m³.

Upstream of the valve chamber the branch which divides the inlet tunnel into two steel pipelines 2.2 m in diameter. The branch is made of reinforced concrete, whereby the downstream part is machined to allow connection to penstocks.

At the beginning of the penstocks the valve chamber is located with installed valves. On each of the two pipes there are two valves – maintenance and operating. In addition to the aforementioned, the valve chamber also includes equipment for drainage the remaining water in the tunnel.

Inlet penstocks are 1.357 m in length, with a diameter of 2.2 m, over 2.1 m to 2 m looking from the valve chamber toward powerhouse. The installed discharge per penstock is 18.00 m³/s. The distance of the penstock axis is 3.0 m. There are a total of seven anchor blocks on the penstock, the longest section between the blocks being 369.0 m and the shortest 98.0 m. Between the anchor blocks, the penstocks are laid on concrete supports with sliding supports at a distance of 15 m. The mounting length of the penstock is 10.0 m. The elevation of the axis at the upstream end is 780.98 masl, while the elevation of the axis at the downstream end of the penstock is 430.8 m.

The powerhouse of HPP "Bistrica" is located at the confluence of the Bistrica River in Lim, on the right bank, next to Nova Varos - Prijepolje. The powerhouse consists of: a powerhouse part, including a erection bay, a control part of the building, as well as a part in which the auxiliary unit is located. The powerhouse part of the building is 15.4 meters wide and 33 meters long. In this part of the building are located two Francis turbines, with vertical shafts and generators directly connected to them.

Existing turbines are of the type Francis, with a vertical shaft, which is connected to the rotor of the generator via middle shaft. Turbines were supplied by Charmilles (for aggregate "A", 1960) and Litostroj (for aggregate "B", 1960).

The basic parts of the turbine are:

— Spiral case with stay vanes,

— Upper and lower turbine cover,

— Guide vanes mechanism,

— Turbine runner,

— Turbine and middle shaft,

— Turbine guide bearing,

— Turbine shaft seal, and

— Draft tube.

The spiral case with stay vanes is divided in six-piece, semi-embedded, made of steel cast iron. It is connected to the inlet penstock through a bell main inlet valve and a pipe Ø1350 mm. The spiral case is supplied with connection to pressure relief valve (pressure regulator).


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The lower and upper turbine covers are mounted on the spiral case. The top cover can be disassembled, and the lower one is embedded. In the upper turbine cover there are openings in which are placed sleeves with the upper sliding bearings of the guide vanes. For the lower turbine cover, a ring is attached where the lower bearings of the guide vanes are installed. The drainage of the turbine cover is carried out over two pipes connected to the draft tube.

The guide vane mechanism consists of a regulating, a regulating mechanism, guide vanes with bearings, regulating levers, pins and their seals. The upper sleeves are lined in a two-part bronze base and sealed with cuffs. On the upper part of the sleeve, the control levers are attached, which are connected via the "eighths" with the regulating ring. On each second control lever there is a safety screw. The material of the original guide vanes was cast steel (ČL 0441), but in those, due to abrasion, during exploitation was replaced with new ones made of stainless steel. All bearings sleeves of guide vanes are supplied with grease from the central lubrication system through their own connections. Manipulation of the guide vane’s mechanism is performed by one servomotor.

The turbine runner is a cast-welded construction made of stainless steel. The surface of the runner is austenitic, brushed with stainless steel rings. The labyrinth rings of the impeller also come from stainless steel. In the flange connection, the runner is connected to the shaft using a screw.

The turbine shaft is made of steel forging and at the ends has flanges for the connection with the runner and middle shaft. The middle shaft connects the runner and generator shaft, which enables the dismantling of the runner up to the turbine elevation without removing the generator rotor.

The turbine guide bearing is mounted over the corresponding brackets on the turbine cover. The turbine bearing is self-lubricating type. The bearing housing is made of steel cast iron, and sliding segments (two, fixed, non-self-adjusting rings) made of babbit metal. Channels for self-lubrication are inserted in the segments. In the channels the oil is supplied through the "pipe", which is immersed in oil, which ensures safe supply and circulation of oil in the bearing. The processed oil from the collecting channel is returned via appropriate pipe with the circulation indicator in the bottom of the tank. Oil level control is performed on oil-glass. By forced circulation of water provided by the multistage pump, cooling of bearing segments (flow of water through appropriate channels) and lubricating oils (flow of water through the “snake” in the oil reservoir) is carried out. The bearing is equipped with one resistant and one mercury remote control thermometer. The temperature control with a resistive thermometer is carried out on a turbine cabinet. The mercury remote thermometer is adjusted to protect the bearing from exceeding the allowed temperature. The original construction of the turbine bearing on the unit "A" was replaced during the exploitation in 1977, and the supplier was "Litostroj".

Carbon seal and labyrinths are mounted on a turbine cover. Two rings of carbon multi-segment seals with springs perform sealing with axial pressure on the respective sealing surfaces. Underneath the lower graphite ring, fine-filtered cooling water is supplied. Sealant or cooling water is supplied through fine filters using a multistage pump. The temperature control is performed by a resistive thermometer. Values are read on the turbine cabinet.

The turbine draft tube continues on the bottom turbine cover. It consists of a cone part, a elbow and a diffuser. The bottom of the siphon is at the elevation of 425.80 m. Tailraces are hydraulically separated. The cone beneath the runner is embedded, and its upper part is partially open for access during the revision and overhaul of the runner (a maintenance opening is provided on the draft tube cone).

In addition, the turbine equipment includes of with a central lubricating grease system: the upper and lower bearings of the guide blades, the connections lever-“eights” and “eights”-regulating ring, the regulating ring bearings, the joint links of the servomotor and the regulating ring and the bearing of the by-pass valve of the main inlet valve.

1.2.2 Technical parameters

Main data and dimensions of the existing Francis turbines of HPP Bistrica are as


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following:

Turbine А B

General data

Manufacturer (turbine/generator) Charmilles / Siemens Litostroj / Koncar

Yearly production 1960 1960

Turbine type Francis Francis

Rated head 360 m 360 m

Optimal head 350 m 350 m

Max gross head (QHE = 1 x 10,5 m3/s, NWL = 812,00 masl)

378.3 m 378.3 m

Min net head (QHE = 2 x 17,5 m3/s, NWL = 812,00 masl)

344.6 m 344.6 m

Rated turbine efficiency (H = 360 m, Q = 17,5 m3/s)

89% 89%

Turbine efficiency for optimal point (H = 350 m, Q = 13,8 m3/s)

91.50% 91.50%

Rated discharge 18 m3/s 18 m3/s

Rated output 52 МW 52 МW

Rated speed 600 min-1 600 min-1

Runaway speed 1070 min-1 1070 min-1

Spiral case

Inlet spiral case diameter 1350 mm 1350 mm

Spiral case angle > 360⁰ > 360⁰

Inlet offset 2380 mm 2380 mm

Layout width 5800 mm 5800 mm

Number of stay vanes 10 10

Guide vanes apparatus


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Turbine А B

Guide vanes pitch diameter 2’300 mm 2’300 mm

Number of guide vanes 20 20

Guide vanes height 180 mm 180 mm

Guide vane’s axis 430.80 masl 430.80 masl

Lubrication of bearing Pressurised grease Pressurised grease

Guide vane material Steel Steel

Turbine runner

Lower and upper ring diameter 2’027 mm 2’027 mm

Runner diameter on inlet 1’975 mm 1’975 mm

Runner diameter on outlet 1’400 mm 1’400 mm

Number of runner blades 15 15

Total height 940 mm 940 mm

Material Steel Steel

Turbine shaft

Outside shaft diameter 510 510

Shaft Lenght 2’630 mm 2’630 mm

Shaft diameter at the guide bearing location

680 mm 680 mm

Middle Shaft

Outside middle shaft diameter 500 mm 500 mm

Midle shaft Lenght 1’760 mm 1’760 mm

Shaft seal


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Turbine А B

Material Graphite FH 27 С Graphite FH 27 С

Number of segments 2 2

Turbine guide bearing

Nominal diameter 680 mm 680 mm

Length of the bearing bedding 380 mm 380 mm

Number of segments 2 2

Draft tube

Height 5’050 mm 5’050 mm

Lenght 8’000 mm 8’000 mm

Inlet cone diameter 1’460 mm 1’460 mm

Outlet cone diameter 1’699 mm 1’699 mm

Cone height 1’750 mm 1’750 mm

Central Lubrication system

Type of apparatus Helios ,,E'' Helios ,,E''

Nominal pressure 294,2 bar 294,2 bar

Lubrication grease Gargoyle Greasse

No 3 or LIS 3 Gargoyle Greasse

No 3 or LIS 3

1.2.3 Operation and condition of existing Francis turbine

From the start of operation 1960. until end of 2018 HPP Bistrica totally produced 19,196,534 MWh, or 55% of total production of all Limske HPP system. Average yearly production is approx. 330 GWh.

Data regarding the production of each Unit from 1960. to end 2018. are given in the following table:

Unit А Б

Fisrt start of the Unit 1960 1960


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Total production, MWh 9’621,459 9’575,075

Number of starts/stops 18’095 18’071

Number of hours in operation, h 263’514 267’135

From the start of operation until now there were no major problems in operation. Foreseen reconstruction is the result of over 40 years of exploitation if equipment lifetime of over 40 years and the need for safe and reliable operation in the next exploitation period. The main objectives of the subject reconstruction are:

— Increase of turbine output,

— Extension of Unit lifetime,

— Increase availability and reliability,

— Reducing maintenance cost.

Some of the major problems in operation of mechanical and hydromechanical equipment in the previous operation are as following:

— Problems with cracks of main inlet valve body (both Units) were repaired many times, with crack logs after the repair;

— Because of inappropriate hydraulic design of pressure relief valve, cavitation problem occurs on the housing and seal;

— Huge leakage through guide vanes, causing the closing of the main inlet valve during Unit’s stoppage. Shaft seal leakage is also present;

— Problem with cooling system pumps for Unit and transformers due to air suction at the pump’s intake for lower water levels in tail race.

1.3 Technical description, data and requirements for rehabilitation and modernization of equipment

1.3.1 Technical description

It has been envisaged to replace completely the existing turbines with the new ones, which precisely includes the following works:

- replacement of all non-embedded turbine parts:

Turbine runner,

Turbine Shaft,

Middle shaft,

Turbine guide bearing,

Guide vanes,

Turbine cover,

Regulating ring,

Draft tube cone,

Pressure relief valve equipment,

Pressure measurement equipment,

Discharge measuring equipment,

Equipment for measuring of Speed rotation increase,

Control equipment and instrumentation.


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- replacement of spiral case with stay vanes, completely embedded,

- retaining of turbine draft tube elbow and turbine draft tube, embedded, in its original shape and dimensions,

- Civil works, necessary for installation of equipment

The new turbines will have to fit new main inlet valves, turbine draft tube (elbow and outlet part), discharge canal for pressure relief valve and the available space in power house.

Two identical turbines will be installed in HPP Bistrica.

The turbine generating unit is of common design, vertical with one thrust bearing, two generator guide bearings and one turbine guide bearing.

Thrust bearing arranged on a bearing bracket just above the generator rotor. The thrust bearing is located in the upper generator bracket, just above the generator rotor. Two guide bearings are located on the generator shaft, one above and one below generator rotor. Turbine guide bearing is located on the turbine cover.

Speed and output are controlled by the guide vane operating mechanism, which is regulated by two hydraulic servomotors actuated by the governor.

The turbine discharge to the draft tube with a draft tube cone. At the exit of the draft tube, the tail race is foreseen with wheel gates at its enabling drainage of the turbine water passage for inspection and maintenance.

Each turbine shall be controlled by an electronic governor and the pertaining electro-hydraulic control system. The governor shall permit speed and power control of each unit individually. Group control of all units in operation shall also be provided (see Secton 2).

Turbines of the HPP Bistrica will be equipped with pressure relief valves.

The general arrangement of the power plant equipment, as well as the layout of the electromechanical equipment, are given in the various drawings and diagrams which are part of this Tender documentation.

1.3.2 Operating condition

Operation of new turbines in HPP Bistrica will take place in the conditions specified below. Design of new Francis turbine in HPP Bistrica have to achieve follows:

- rated discharge of 19 m³/s,

- high efficiency in range for discharges of 75%-100% of rated discharge, for appropriate net heads. Special attention has to paid for partial regimes as outlined below.

HPP Bistrica has its own reservoir with total volume of 7,5·106 m³, and usable volume

of 4·106 m³.

For usual operating regimes of HPP Bistrica, level in the reservoirs is maintained at a value close to the maximum, which is achieved by optimal utilization of the units.

The maximum values of the reservoir elevation HPP Bistrica are given in the table.

Tail race water level of HPP Bistrica is determined with water level reservoir in HPP Potpec, amounting 435.60 masl. When the normal water level in HPP Potpec is below tail race (431.10 masl), tail race water level of HPP Bistrica depends on turbine discharge and for installed HPP discharge is 432.89 masl, while for technical minimum (9,5 m3/s) is 432.23 masl. (the technical minimum is forecast and will depend on the guaranteed data entered in the technical data table)

Generally net head is changed due to change of water elevation in reservoirs (head and tailrace) and head losses in inlet structures which are consist of common concrete tunnel and two steel penstocks, one per each turbine.

Basic data for tunnels and penstocks for HPP Bistrica are given in the table (point


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1.3.3).

Considering that changes of water level in reservoirs are small, significant net head changes due to head losses which depend of discharge through turbine.

Net head values in relationship with characteristic discharges through each turbine, are given in table (point 1.3.3).

- Taking into account that the turbine discharge is increased from 18,0 to 19,0 m³/s, and the fact that the existing tunnels, surge tank, and penstocks are going to be kept, Contractor is obligated to perform transient analyses calculation for the following goals:

- determining required Unit’s moment of inertia (turbine and generator),

- closing law of guide vanes,

- opening law of pressure relief valve,

- overpressure in penstock,

- oscillation of water level in the surge tank.

Operating regimes of turbine depends from daily and current needs of electrical power system of Republic of Serbia.

In this period turbines are engaged with different outputs, depending on the current needs of the system, but in recent years more and more pronounced tendency to engage Units in the range 75 - 100% power, but also with partial loads lasting 40 days/year.

Generally, turbines are more engaged in the winter and rainy periods and shorter in summer and dry season.

Operating regimes

At the following diagram the operating range of turbines with expected outputs are given:

Data for the working points at the diagram are given in the following table:

Working point

Number operatio

n turbines

Reservoir water level

[masl]

Tail race water level

[masl]

Turbine discharge [m3/s]

Net head [m]

Turbine output

Pт [МW]


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1 1 807.00 435.60 9.50 361.98 26.94

2 1 812.00 432.23 9.50 373.70 27.50

3 1 812.00 435.60 18.00 357.07 58.3

4 1 812.00 435.60 19.00 354.86 61.20

5 (РТ) 2 810.00 435.60 19.00 337.00 58.27

6 2 807.00 435.60 19.00 333.73 57.76

Turbines were operating 4’500 hours/year, with average 310 start/stops/year.

1.3.3 Technical parameters of new turbines

Hydraulic parameters

Hydraulic parameters for design of new turbines of HPP Bistrica are as following:

Technical description HPP Bistrica

Reservoir

- Useful volume (milion m³) 4·106

- normal water level (NWL) (masl) 812,00

- mean water level (MWL) (masl) 810,00

- minimum water level (MinWL) (masl) 807,00

Tail race water level

- Maximum operating water level (m a.s.l.) 435,60

- Mean operating water level (m a.s.l.) 435,60

- Minimum operating water level (m a.s.l.) 432,23

Concrete Tunnel

- Entrance elevation (m a.s.l.) 794,98

- Exit elevation (m a.s.l.) 780,98

- Length (m) 8’026,0

- Diameter (mm) 4’000

Surge tank

- Type differential

- Inner cylinder diameter (m) 4,25

- Outside cylinder diameter (m) 16,20

- Length of lower chamber (m) 55,0

- silencer type Asymmetric (1:2,95)

- silencer opening (m) 2,30/1,20


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Technical description HPP Bistrica

- allowed silencer resistance (m) 8,0

- water level for dynamic behaviour (masl) 785,51

- maximum water level for dynamic behaviour (masl)

820,20

- lower chamber volume (m3) 1’400

- upper chamber volume (m3) 3’000

Steel Penstock

- Entrance elevation (m a.s.l.) 780,98

- Exit elevation (m a.s.l.) 430,80

- Length (m) 1357,0

- Diameter (mm) 2200/2100/2000

Gross heads

- Maximum gross head, Hbr.max, (m) 379,11

- Mean gross head, Hbr.max, (m) 374,40

- Minimum gross head, Hbr.max, (m) 371,40

Head losses in water passage system

ΔH = 0,01481 𝑄𝑡2 + 0,04513 𝑄𝑐

2

Net heads

- Maximum net head (m) 373,70

- Maximum net head for one turbine operating with rated discharge (m)

354,86

- Rated net head (m) 337,00

- Minimal net head (m) 333,73

Technical data of new turbines

In the following table the expected data for the new turbines are given:

Technical description Unit HPP Bistrica

Number of units - 2

Type of turbine -

Vertical Francis

Maximum plant output (turbine) МW 115,6


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Technical description Unit HPP Bistrica

Rated turbine output at rated head, Hr = 337.00 m

МW 57,80

Maximal turbine output for max net head, Hn = 352,90 m

МW 60,95

Turbine speed rev/min 600

Rotational direction of turbine runner - clockwise

Elevation of spiral case center line masl 430,80

Maximum permissible pressure rise % 30

Maximum permissible speed rise % 45

Installed turbine discharge m3/s 19

Maximum working pressure for all parts under water pressure (design pressure)

bar 50

Test pressure for all parts under water pressure

bar 75

Cooling water temperature range °C 10 - 25

Spacing between intake trash rack bars mm 50

Values given in the above table are predictive and non-binding.

Values given in the Schedule of technical data will be governing and guaranteed by the Contractor.

1.4 Special guarantees for turbines

For general conditions of guarantees, reference is made to General Technical Conditions.

The Schedule of Technical Data referred to under this clause and the subsequent clauses of these Special Technical Requirements, is provided below.

Penalties are given in the Contract part of Tender documents.

1.4.1 Guaranteed turbine output

The Contractor will guarantee the following turbine outputs:

Rated turbine output, for rated discharge and rated head, and

Max turbine output for rated discharge and reated head, one unit in operation with rated discharge.

Minimal accepted rated turbine output will be 57,5 MW.

Minimal accepted maximal turbine output (one turbine in operation with rated discharge) will be 60,5 MW.

For calculation of the turbine output the following data will be used:

Water density: 999 kg/m³.

Gravity acceleration: g 9.804 m/s².

Guaranteed outputs will be measured at the model and confirmed at the final


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prototype tests.

If the turbine outputs measured at the model are lower then guaranteed, the Employer is entitled to a contractual penalty defined by the Contract.

If the turbine outputs measured at the protype are lower then guaranteed, the Employer is entitled to a contractual penalty defined by the Contract.

1.4.2 Turbine Efficiency

The turbine efficiency guarantee is met if the weighted average efficiency of the turbine, computed from the measured values on the model to prototype, is not less than the guaranteed weighted average efficiency indicated in the Schedule of Technical Data.

The weighted average efficiency will be computed in accordance with IEC Publication 60193, Annex F:

Weighting coeff. ''C'':

Weighting coeff. ''C'' for:

Net head (m)

Discharge (m³/s) 337.00 347.00 354,86 361.98 373,70

19 17 12 10 0 0

18 19 13 11 0 0

15 0 0 6 0 0

13 0 0 5 3 0

9.5 0 0 0 2 2

The ''weighted average efficiency'' to be guaranteed by the Contractor is defined as follows:

weighted average = ∑(C ⋅N / 100)

- N being the individual efficiency and

- C the corresponding weighting coefficient according to the above chart.

The individual values of turbine efficiency have to be indicated in Schedule of technical data.

The average weighted efficiency will be guaranteed at the prototype calculated from the model according to IEC 60193 (Annex F).

Minimal acceptable average weighted efficiency according to the above coefficients is 92.5%.

Guaranteed weighted efficiency will be measured and guaranteed at the model.

If the turbine average weighted efficiency measured at the model is lower than guaranteed, the Employer is entitled to a contractual penalty defined by the Contract.

1.4.3 Discharge Guarantee

The Contractor shall guarantee the rated and minimum turbine discharges for normal water level in reservoir 812.00 masl. on the Model

Discharge values will be given in the Schedule of Technical Data.

If the turbine rated discharge measured at the model is lower than guaranteed, the Employer is entitled to a contractual penalty defined by the Contract.

If the turbine minimal discharge measured at the model is higher than guaranteed, the Employer is entitled to a contractual penalty defined by the Contract.


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1.4.4 Pressure and Speed Rise

Pressure rise

Guaranteed max pressure at the entrance of the spiral casing due to sudden load rejection under the most unfavourable regime will be indicated in Schedule of Technical Data.

Maximum pressure which occurs during the exploitation will be also indicated in the Schedule of Technical Data.

Compliance with the guaranteed pressure surge values shall be proved by calculations and verified by field tests.

Indicated pressure rise in the Schedule of Technical Data cannot exceed 30%.

Speed rise

The transient speed rise for sudden load drop as stated in the Schedule of Technical Data is to be guaranteed.

Compliance with the guaranteed speed rise values is to be proved by respective calculations and verified by field tests.

Max rotation speed rise is 45%.

If, during tests, the pressure and speed rise are higher than guaranteed, the Employer has the right to reject turbine.

1.4.5 Runaway Speed

The maximum runaway speed as stated in the Data Schedules for the maximum static head will be guaranteed. Duration runaway speed must be at least 5 min

Compliance with the guarantee shall be proved by model tests, and at the option of the Employer, be verified by field testing.

If the runaway speed is higher than guaranteed values during tests, the Employer has the right to reject turbine.

1.4.6 Specific Guarantee for Critical Speed of Shaft

The first critical speed of the rotating parts of the turbine/generator set shall not be less than 25% above turbine maximum runaway speed, and it shall be checked and guaranteed by the Contractor, by respective calculation.

If the value of the critical shaft speed obtained by calculatin is higher than guaranteed during tests, the Employer has the right to reject turbine.

1.4.7 Specific Guarantee for the Turbine Shaft Run-out

Run-out of the shaft shall be guaranteed by the Contractor and tested on the Site, including the most unfavourable operation conditions.

The guaranteed value of shaft run-out shall be in accordance with the value indicated by the Contractor in the Schedule of Technical Data.

Only the first-class accuracy for the run-out value, in accordance with the internationally recognized standard ISO 10816-5: 2018, class A in normal operation, shall be accepted. In partial operating modes, the value shall fall under Class B.

If the value of the shaft run-out is higher than guaranteed during tests, the Employer has the right to reject turbine.

1.4.8 Specific Guarantee for Axial Hydraulic Thrust

The maximal and minimal axial hydraulic thrust, occurring under the most unfavourable transient conditions, shall be guaranteed as indicated by the Contractor in the Schedule of Technical Data.

Compliance with the guarantee is to be proved by model tests and verified by field measurements.


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If the value of the hydraulic thrust is higher then guaranteed during tests, the Employer has the right to reject turbine.

1.4.9 Guide vanes leakage

If the leakage through the completely closed guide vanes (with the unit stopped and main inlet valve opened) are higher than guaranteed in Technical Data Sheet, the Employer has the right to reject turbine.

1.4.10 Cavitation

Referent spiral axis elevation is given in Point 1.3.3. of this Section 1.

As critical value of turbine cavitation coefficient the value that corresponds to efficiency decrease of 1%, shall be adopted.

1.4.10.1 Cavitation Guarantees for Prototype

The cavitation guarantee value shall be verified within the cavitation guarantee period of the turbine, i.e. after 3’000 hours after the Taking Over of the turbine, or within Defect Notification Period, whichever expires later.

1) Loss in weight (mass)

If after 3000 hours of turbine the loss of the material of the turbine runner due to cavitation is detected, the Employer and the Contractor shall jointly carry out the testing of the volume of the pitting material, as defined in IEC 60609. If it is determined that there is a pitting of material, the Employer has the right to a contractual penalty defined in the Contract.

2) Volume and depth of cavitation pitting

Cavitation shall be guaranteed also with respect to maximum depth of pitting and maximum runner volume affected whereby principally the corresponding recommendations of the "Cavitation Pitting Evaluation in Hydraulic Turbines, Storage Pumps and Pump-Turbines" (IEC - Publication 60609) as adapted as follows shall apply for the first 3000 working hours after provisional acceptance of the turbine:

For cavitation damage up to 0.50 times the values as per the charts' upper curve: tolerable.

For damage between above 0.50 and 1 times the values as per the charts upper curve: immediate and full repair and reconditioning of the runner by and at the cost of the Contractor.

For damage above 1 times the values as per the charts' upper curve: earliest replacement of the unsatisfactory runner by a suitably rectified or redesigned and model-tested one whereby all related cost shall be at the charge of the Contractor. Such new runner shall be subject to the same guarantee period as the replaced one.

Should depth of pitting and/or runner area affected be again above 1 times the values as per the charts' upper curve then the turbine may be rejected.

If within the Defects Liability Period stated above and under the operating conditions, the turbine runner or other parts become excessively pitted, the Contractor shall repair the pitted places and correct the profile in a satisfactory manner by welding with stainless steel material.

During the cavitation Defects Liability Period, the Contractor shall be permitted to inspect the turbine. The first inspection of the runner and other parts subject to cavitation shall be carried out at the end of the first year of the exploitation, after the Trial Run. Further inspection will be decided by the Employer if deemed necessary. During the cavitation Defects Liability Period, the Contractor is not entitled to carry out any correction on the runner profile unless permitted by the Employer. The Employer will have the right to reject a turbine runner if the cavitation guarantee is not fulfilled, or if more than three corrections, done by the Contractor at his expense,


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have not brought sufficient improvement.

The cavitation guarantee does not apply to erosion or damage caused by suspended matter in water.

The amount of cavitation pitting for the prototype shall be evaluated in accordance with the recommendations of last edition of the IEC 60609.

If determined that there are cavitation pittings in certain volume and depth, , the Employer is entitled to a contractual penalty defined by the Contract.

1.4.11 Stability of the System

The Contractor shall carry out the stability study by mathematical simulation of the entire water conveying system (transient analyses-water hummer) including also the turbine performances ensuring system stability under all load conditions.

The transient calculations with water hammer analyses shall be carried out by the Contractor with the basic assumptions and numerical data available:

On drawings for the water conveyance system;

The hydraulic characteristics of the turbine/generator.

The Contractor shall take into consideration the following assumptions, parameter values and their numerous combinations:

Water levels of the main reservoir and extreme water levels in the tail water;

Various operations (start-up, normal shut-down, trip-off, guide vane closure or failure to operate, etc.), within the normal and emergency operating mode changes;

Ranges of turbine heads, operations under the most unfavourable load conditions.

The Contractor shall submit the following results and justify that the most unfavourable though realistic conditions have been calculated and analysed:

Maximum and minimum pressure in the spiral case;

Maximum transient rotational speed;

Total momentum of inertia for the unit’s rotating parts;

Closing law of the guide vanes;

Closing law of the inlet valve;

Opening law of the pressure relief valve.

At least the following load cases for transient and water hummer calculations will be carried out:

1) Water hummer

- Load rejection from the grid with fast closure of guide vanes,

- Load rejection of one Unit (normal case), and not opening of pressure relief valve on another Unit,

- Start of one Unit for elevation 807.00 masl in the reservoir,

2) Transient analyses

- Load rejection of both Units from the grid,

- Start of one Unit,

- Start of one Unit for elevation 807.00 masl in the reservoir,

- Simultaneous start of both Units

- Load rejection after the start of the Units,


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- Quick start of the Units after recent stoppage.

The Contractor shall supply a report describing the calculation method, a brief software description (including validation), computation assumptions, input data, results and analysis. Study shall be conducted for conditions including parallel operation with the infinitive network. The study shall indicate the setting range of the governor parameters for which the system is stable after any disturbance. As far as applicable, the governing system shall comply with IEC 61362 and IEC 60308.

A preliminary transients report shall be submitted in advance to the Employer for approval.

1.4.12 Pressure Pulsation, Resonance Phenomena

It will be guaranteed that in any of the operating regimes (including transient conditions and water hummer) no harmful vibration in the head cover, shafts, bearings and guide vanes, draft tube, etc. will occur and no harmful pressure fluctuation in the draft tube and between the guide vane and the runner will occur within guaranteed values.

Amplitude and frequency of the pressure pulsation within draft tube and spiral case shall be indicated in the Schedule of Technical Data.

Pulsation frequency shall be at least 30% lower or higher than the natural frequency of the rotating equipment (turbine and generator).

1.4.13 Power Fluctuations

Guaranteed limits to power fluctuations are variation in power output measured at the generator terminal becoming ± 1.5 % of the maximum power (with included measurement tolerance according to standards for measurements and tests of turbine). The values shall be indicated in the Schedule of Technical Data and shall be guaranteed by the Contractor.

One (1) minute peak-to-peak analyses will be performed to determine ± ΔP.

1.4.14 Turbine runner

Mechanical Behaviour

The guarantee concerning mechanical behaviour shall cover a period of 3’000 working hours or 2 years from the issuing of the Takin over sertificate, whichever expires earlier.

During this period, the runner and turbine auxiliary equipment will be periodically inspected, at least within the following intervals:

- at the end of the Trial Run as indicated in the General technical conditions,

- every 2500 hours of operation till the expiration of the Defect Notification Period

The inspection shall be performed in compliance with the procedure for the inspection of the finish-machined runner and turbine auxiliary equipment for defects on the surface, and the same limits of acceptability shall apply as specified for Material Test, Clause 7.1 of this Section 1.

Such inspection shall be carried out by the Contractor’s experts trained for such type of tests in accordance with General and Special Technical conditions, with presents of Employer representative.

He will issue a report from each inspection carried out and submit it to the Employer.

If the inspection carried out during the guarantee period should reveal an appearance of cracks in any portion of the runner, the Employer reserve the right to apply one of the following procedures:

a) If the cracks or other defects are minor and do not demonstrate any systematic character, the Contractor will be bound to eliminate or repair mentioned defect at his own expense according to the approved and recognized method,


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b) If the cracks or other defects are demonstrating systematic character, the Contractor will be bound to recommend method of general repair followed by thermal treatment.

For all repairs the Employer’s approval has to be obtained and such repairs shall be considered as final and successful and provide the operation of 2500 hours without appearance of new cracks.

If after one repeated repair new cracks should continue to appear after the expire of Defect notification period, the Employer reserves the right to reject the runner.

Repairs Performed by Contractor

During the Defect Notification Period, all necessary repairs of the runners and turbine auxiliary equipment shall be carried out by the Contractor at his own expense.

This refers in particular to the following:

- minor anomalies of metallurgical origin, such as mill defects or cracks;

- rectifications due to incorrect shape and surface quality of the runner blades to eliminate cavitation and improve hydraulic performance.

Normal uniform erosion wear will not be considered as a fault covered by this special guarantee.

1.4.15 Noise

Within the whole operating range the Contractor shall reduce the noise of the turbine and its auxiliary equipment as low as possible. The noise level at:

- 1 m from the turbine,

shall be indicated in the Schedule of Technical Data and guaranteed by the Contractor.

Max allowed noise is 85 dB.

1.4.16 Vibrations

Guaranteed vibrations limits of the shafts, turbine guide bearing and turbine cover will be defined in Schedule Technical Data, and Contractor will guarantee these values.

For the following conditions, the Contractor will guarantee the following class of vibrations:

1. From 75 to 100% of rated turbine discharge:

- Shaft vibrations (run-out), relative vibrations, Class A according to standard ISO 20816-5:2018;

- Turbine guide bearing, absolute vibrations, Class A according to standard ISO 20816-5:2018;

- Turbine cover, absolute vibrations, Class A according to standard ISO 20816-5:2018;

2. From 40-75% of rated turbine discharge:

- Shaft vibrations (run-out), relative vibrations, Class B according to standard ISO 20816-5:2018;

- Turbine guide bearing, absolute vibrations, Class B according to standard ISO 20816-5:2018;

- Turbine cover, absolute vibrations, Class B according to standard ISO 20816-5:2018;.

If the guaranteed values of vibrations exceed the above-mentioned values during tests, the Employer reserves the right to reject the whole Unit.

Note:

https://www.iso.org/standard/67919.html











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All above mentioned test will be carried out on available head during the start of the Unit.

All the tests described above will be carried out at a head that is available at the time of commissioning of the appropriate unit. For heads higher than the above-mentioned, all major tests will be repeated at the intervals agreed between the Contracting Authority, the Employer and the Employer Representative, depending on the extent of the increase in the available head.

These tests will be repeated up to the maximum operating head, even if it occurs after the expiration of the Defect notification period.

The obligations of the Contractor in relation to specific guarantees, whose conformity has not yet been proven by the tests, will accordingly be extended.

1.4.17 Turbine Guide Bearing

Temperature rise

Turbine guide bearing shall be able to operate properly continuously within the range of 40-115% of the rated power for an unlimited number of hours, and at least one hour at a speed of 115% to 180%, as well as within the range of 0% to 40% for two hours.

The maximum bearing temperatures shall be as follows:

- Operating temperature below 50 °C,

- Temperature setting ALARM 50 °C,

- Temperature setting TRIP 60 °C.

The Contractor shall guarantee the above temperature limits.

The Contractor shall further guarantee oil tightness of the bearings. If there is any oil leakage on the bearing, the Employer reserves the right to reject such bearing.

Bearing losses

The Contractor shall submit an updated design and calculation of the turbine bearing specifying bearing losses in kW. The Contractor shall guarantee such bearing losses.

If the measured bearing losses under nominal conditions are higher than 125% of the guaranteed values without tolerances, the Employer shall be entitled to reject the bearing in question.


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2. SCOPE AND LIMITS OF SUPPLY

2.1 General

This clause specifies only the main equipment and components to be supplied and works to be done by the Contractor for the fulfilment of Section 1 of this Contract, covering the supply and services necessary for two vertical shaft Francis turbines according to this Specification.

The Contractor is bound, however, to provide complete works, even if equipment or work to be done are not mentioned specifically in the following description of the scope of supply.

The items enumerated under the following clauses refer to the minimum general requirements of one turbine, but these requirements shall apply to each of the two turbines to be supplied and any interface equipment deemed to be necessary between them, except where stated otherwise.

The specific requirements to be applied for the various components are set forth under Clause 4 of this Section 1.

Scope of Contractor’s supply for Section 1 is the following:

2.2 Turbine model tests,

2.3 Dismantling and transport of existing equipment,

As per General technical requirements.

2.4 Design (as per Point 1.3.3) and manufacturing of the following turbine equipment:

- 2 (two) Francis turbine runners,

- 2 (two) turbine shafts,

- 2 (two) middle shafts,

- 2 (two) turbine guide bearings,

- 2 (two) steel spiral cases with stay vanes,

- 2 (two) upper and lower turbine covers,

- 2 (two) regulating rings,

- 2 (two) guide vane servomotors,

- 2 (two) draft tube cones,

- 2 (two) turbine shaft seal with installation,

- 2 (two) pressure relief valve, complete with necessary valves and hydraulic.

- 2 (two) sets of pressure measuring equipment,

- 2 (two) set of equipment for measuring of speed rotation,

- 2 (two) set of control equipment and instruments for turbine,

- 2 (two) set of equipment for vibration measurements,

- 2 (two) set of equipment for measurement of axial force.

2.5 Design and manufacturing of the pressure relief valve equipment:

Contractor will supply the following equipment:

- 2 (two) pressure relief valve, complete with necessary valves and hydraulic equipment.


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2.6 Spear parts

Contractor will supply spare parts for both turbines:

- One (1) complete set of cylinder rings for servomotors,

- One (1) complete set of turbine packages and seals, except the turbine shaft seal,

- One (1) of each contact switch, selecting switch and selecting speed switch of all types,

- One (1) of each electromagnet coil of each type and sizes,

- One (1) complete set of guide vane levers,

- One (1) set of guide vane lever,

- Three (3) guide vanes,

- One (1) connection parts for connection of levers with regulating ring,

- One (1) turbine guide bearing cooler,

- One (1) temperature resistanse detectors,

- One (1) of each inductive instruments for all used types,

- One (1) part of each equipment and control instruments

2.7 Transport of new equipment,


2.8 Installation of new equipment

As per General technical requirements and Point 4 of this Section.

2.9 Tests and commissioning of new equipment

as per Point 7.

2.10 Obligations during Defect notification period


2.11 Miscellaneous

If not otherwise required the material referred to under the following clauses of the scope of supply shall only be supplied once by the Contractor for the entire hydro power plant.

Oil and Grease

Complete filling and supply for the turbine guide bearings, as well as sufficient grease and other lubrication oil necessary for all remaining lubricating requirements on taking over of the equipment.

Contractor will supply first filling of oil with 25% reserve of total volume, for each type of oil.

Furthermore, Contractor will supply one more one more filling of oil for one turbine.

Minor Accessories for Each Turbine

- All necessary checkered plates for covering the floor around all valve spindles and other parts supplied under this Section 1, which pass through the floor and are not embedded in concrete,

- All platforms, walkways, ladders, guards and hand-railing necessary to obtain easy and safe access to all equipment supplied under this Section 1,

- Nameplates for each separate item of equipment showing the manufacturer's


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name, serial number, year of manufacture, type, rating capacity and other main characteristics in accordance with General technical requirements.

Special Tools

- All necessary tools and equipment for erection and maintenance to be furnished in accordance with Clause 4.2.9 of this Section and General Technical Requirements.

Corrosion Protection

- Of all previously mentioned items in accordance with General Technical Requirements, and Clause 5 of this Section 1.


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3. DOCUMENTATION

3.1 General

All Tables and Lists from these tender documents must be fulfilled by the Contractor.

Documents to be submitted with the Tender shall serve for presentation and detailed evaluation of each submitted Tender.

3.2 Documentation to be Submitted with the Bid

The following technical documentation shall be prepared and submitted with the Tender:

Technical Description

Technical description of replacement, upgrading & installation of new equipment and refurbishment of existing equipment to be kept, which is subject of the Section 1.

It has particularly to consider parts of the equipment, as specified and required at Clause 2., item by item.

Description shall comprise technical details in order to present how the Tenderer proposes and intends to perform replacement, reconstruction, rehabilitation, and upgrading of the equipment. Characteristics of the proposed equipment shall be stated as well.

Drawings and Schemes

to present the Tenderer’s proposal and to illustrate his Technical solution.

Turbine Hill Diagram

Means the diagram of discharge versus head, with efficiency, power output and suction head curves presented, for the whole range of heads and discharges.

Taking into account specific requirements and imposed limits regarding replacement, reconstruction and upgrading of the turbine (rotating parts, non-rotating assemblies, embedded parts partly and auxiliary equipment), on one hand, and possible lack of a corresponding hydraulic turbine model data for estimation of such specific reconstruction effects, on another hand, the Tenderer is supposed to submit proposed turbine hill diagram, as well as description of methodology and approach of elaboration of such submitted turbine hill diagram.

Applied methodology and approach must be fully justified by the Tenderer, in order to convince the Employer that submitted-proposed turbine hill diagram could be considered as realistic and for guaranties (later on to be verified by hydraulic model testing – as required by the Requirements).

Detailed Tenderer’s Program of Works

The Tenderer has to present and submit his Detailed Program of the Works (overall), based on General Program of Works and Key Dates from this Tender/Contract Documents. All activities regarding the main equipment subject to this Section 1will be described in Program of works.

In his Detailed Program of Works (overall) the Tenderer has to show time, sequences and Key Dates of the activities on the main equipment (Site inspection, Plant and equipment data acquisition, Pretesting of Equipment, Design activities, Model testing, Procurement of material, Production of new equipment, Dismantling of equipment, Refurbishment of the equipment that is to be kept, Erection on the Site, Precommissioning & Commissioning, Trial Operation and Taking Over), which is subject to this Section 1.

Key dates from the General Program of Work must be unconditionally respected.

For the purpose of this Section 1, the Tenderer shall prepare an extract from his submitted Detailed Program of the Works, referring in more details to the equipment and activities for this Section 1.


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Program of Inspection, testing and control

of the equipment during production, erection and commissioning including general Quality Control Plan – Program (standard procedures and forms).

Description of Methodology and Instrumentation for Testing of Guaranteed Data

on the prototype (Site) as required by the Tender/Contract Documents (rated power, cavitation, transients etc.).

Prospectus and leaflets of standard equipment

List of materials

will be summary list of materials by the positions from Schedule of technical data and given through Tender (name of material and standard).

Others

which in opinion of the Tenderer can present and support his Tender.

3.3 Documentation to be Submitted after Contract Commencement date

3.3.1 General

The Documentation to be submitted after contract commencement shall include, but shall not be limited to, the following documents:

- Construction design (CD), in line with General technical requirements,

- As-build design (AD), in line with General technical requirements,

The contractor will show in the design all necessary details of the as-build design of subject equipment:

- documents described and mentioned in this Section 1,

- specific calculations, drawings and instructions, listed in here below

3.3.2 Specific Calculations

- Special turbine calculation should include an analysis of possible resonance during turbine operation due to hydraulic, mechanical and electric excitation.

- Calculation of the transients with water hammer analyses,

- turbine runner stress calculation by finite elements method (including stress calculation of blades and of hub),

- turbine shaft stress calculation including checking of shaft vibrations and shaft critical speed calculation,

- calculation of the hydraulic axial thrust,

- calculation of temporary speed rise pressure surges in waterways and hydraulic axial counter-force during different transient regimes (50%, 75%, 90% and 100% load rejection),

- stress calculations of stay vanes, upper and lower turbine cover, guide vanes by finite element method,

- guide vane closing and opening forces calculation,

- calculation of critical speeds of turbine shaft and middle shaft,

- calculation of technical resources of all dynamic loads of turbine parts, including all runner parts, shaft, wicket gate, turbine stay ring and runner casing,

- civil design drawings related to the turbine.

3.3.3 Specific Drawings

- turbine general arrangement drawings,

- turbine longitudinal section


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- turbine cross section,

- turbine runner drawings,

- draft tube aeration drawing,

- turbine assembly drawings,

- turbine upper cover drawing,

- turbine lower cover drawing,

- turbine shaft drawing,

- middle shaft drawing,

- turbine shaft seal assembly drawing,

- turbine shaft seal segment drawings (details),

- turbine shaft sealing ring (details),

- turbine shaft springs for sealing rings,

- installation of probes for measurement of turbine sealing temperature,

- guide vane apparatus (distributor) assembly drawing,

- assembly drawing of guide vanes,

- detail drawings of all bearings for guide vanes and lubrication scheme,

- assembly drawing of guide vanes servomotors,

- detailed assembly drawing of guide vanes kinematic elements,

- detailed drawings of guide vane and its bearings with details considering machining and installation,

- spiral case drawings, in the scope sufficient to show and explain in details all planned and approved rehabilitation works,

- assembly drawings of turbine head cover,

- assembly drawing of turbine guide bearing,

- turbine guide bearing segment drawings,

- cooling water system and lubrication schemes for turbine guide bearing,

- drawings for installation of high pressure unit lift pumps,

- turbine runner drawings before machining, including each blade casting with results of all checking (according to CCH 70-3) from foundry before runner assembling,

- turbine runner assembly drawings after machining with clearly indicated roughness on different vanes (according to CCH 70-3),

- turbine runner dismantling drawings,

- assembly drawing of new turbine runner casing, draft tube cone and draft tube,

- turbine upper cover drainage drawings,

- fundament drawings.

3.3.4 Instructions

Upon completion of the detailed design, the Contractor shall submit detailed instructions for storage, installation, checking and start-up, testing, operating and maintenance of each item of the equipment.

Operating and maintenance instructions will be on Serbian and shall include applicable drawings, applicable parts list and catalogue covering all equipment furnished and may be needed or useful in operation, maintenance, repairs,


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dismantling or assembling.


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4. DISMANTLING AND INSTALLATION REQUIREMENTS

4.1 General

Dismantling, installation and commissioning of the equipment will be carried out by the Contractor's personnel under the direction of his responsible staff, speaking and writing English fluently. The services of the Contractor's personnel shall include also the test run period during which they will attend to the equipment and instruct the Employer's staff in operation and maintenance of the equipment.

The Contractor's activities will include any work related to the installation, erection, adjustment and commissioning of all equipment supplied under this Contract, including interfaces with other Contractor's supplies. All minor work necessary for the completeness of installation. erection and commissioning shall be included.

For the erection and commissioning of the supply covered by this Contract, beside the general installation requirement, the following special conditions defined in this Section and the General Technical Requirements apply.

4.2 Spiral case and stay vanes

All required anchor and anchor bolts to be placed in the first stage concrete shall be supplied by the Contractor and their position and anchorage indicated in the foundation drawings.

After assembly of the spiral casing sections and at regular intervals during welding of the field joints, the alignment, levelling and roundness of the construction shall be carefully checked and records shall be taken and delivered to the Employer for review. The weldings are to be tested in accordance with the requirements specified in Clause 7 of this Section.

After complete installation the spiral casing shall be prepared for hydrostatic pressure testing by bolting or welding the pressure head cover to the extension pipe, inserting the test ring into the stay ring and by adequately bracing the stay ring according to the detailed instructions of the Contractor.

For the performance of the hydrostatic pressure test, test pressure shall be gradually increased to 75 bar and will be maintained at this pressure for at least one hour, after all leaks have been eliminated. All details for the test procedure shall be determined by the Contractor.

During and after the hydrostatic pressure test, micrometer measurements shall be taken to determine the amount of movement of the machined surfaces of the stay ring and to check the expansion of the spiral casing circular portions. Records of these measurements shall be taken and delivered to the Employer for review.

For pressure testing all piping attached to the spiral casing including piezometer piping shall be installed and pressure-tested together with the spiral casing.

All equipment for performing the hydrostatic pressure tests, including pump, valves, gauges, thermometers, and micrometres, shall be supplied and installed by the Contractor.

After successful completion of the hydrostatic pressure tests the spiral casing shall be prepared for second stage concrete. The concreting procedure shall be proposed by the Contractor, and is subject to the approval of the Employer. During the concreting and its checking period, the spiral casing shall remain filled with water at a pressure specified in the approved concreting procedure. The water in the spiral casing shall be continuously circulated by suitable means provided by the Contractor for cooling of the concrete.

Care shall be taken to ensure that all piping such as pressure measurement tappings will not be deformed or damaged during Contraction of the spiral casing after release of pressure.

Installation tolerances of spiral casing:


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- The parts of the turbine shall be installed so that the concentricity, level of circle

center, alignment, and fit of the parts are as close as possible to the design

requirements. The following tolerances will be permitted, provided that tolerances

preventing satisfactory operation of the turbine or related equipment will not be

accepted.

- The turbine stay ring and spiral case setting for the turbine shall not deviate from

the vertical and horizontal center line elevation and dimensions shown on the

Drawings by no more than 2 mm.

- The level of the finished surface that will support the head cover, when measured

at eight points 45' apart, shall be maintained to within 0.2 mm maximum variation

from highest to lowest point.

- The circularity and concentricity of the stay ring and other parts, at points that will

affect impeller runner clearances and at points that will affect the fit of non-

embedded parts, shall be maintained to such tolerances that the net clearances

for rotating parts shall be not less than one-half of the design clearances.

The net clearances between stationary parts shall be not less than one-fourth of the net design clearances.

4.3 Installation of removable turbine parts

The removable parts shall be carefully cleaned from protective coatings and any traces of corrosion shall be removed before installation.

For the issue of the "Complete and Ready for Commissioning Certificate' the following checks shall be performed:

- Verification of the perfect alignment of all turbine parts. For the alignment and

runout of the shafts the procedure as provided in the NEMA Standards,

Publication No.MG5.2-1972 (Installation of vertical Hydraulic Turbine-Driven

Generators and Reversible Generator Motors for Pumped Storage Installations)

shall apply,

- check of all clearances, with particular view to turbine guide bearing,

- performance of a pressure test of servomotors and all control piping with double

of the normal working pressure,

- check of the prestressing and perfect locking of the bolted connections.


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5. DESIGN, MATERIAL AND WORKMANSHIP

5.1 General

All parts of the Plant shall be designed and manufactured in the best and fully suitable manner with materials best suited to their purpose and in accordance with recognized standards of good practice and latest technology.

Also transient and emergency conditions, such as overload, generator short-circuit, runaway speed of at least 5 minutes duration shall be withstood without detrimental vibrations or distortions.

In view of the disastrous consequences which may result from failure of even minor parts under water pressure, the Contractor shall design and manufacture all such parts on a highly conservative basis.

The design of the equipment shall provide all reasonable precautions for the security of the personnel engaged with/operation and maintenance and shall meet the relevant safety regulations and standards specified in the General technical requirements.

Wherever practicable, the design and shaping of important components shall be such as to facilitate full non-destructive tests.

The Contractor shall provide proper preparation of all parts for field welding and bolted connections. All connecting parts are to be match-marked, shop-assembled and dowelled.

Welding seams shall be ground flush on all surfaces in contact with water.

Special attention shall be paid to quiet and vibration-free operation of the turbines and all auxiliary equipment.

The Contractor shall furnish the necessary bracing and/or tightening devices to maintain true shape of parts during shipment, unloading, assembly and erection.

Partition of components shall be selected considering transport limitation, easy erection and maintenance, and will be subject to the Employer's approval.

Any water and air traps in the equipment shall be avoided.

All bolts and nuts which are not accessible or are liable to loosen in operation shall be secured in a proper manner, excluding spot welding.

All shut-off valves shall be of the rising stem type. Shut-off valves which would endanger the equipment, if operated inadvertently, shall be supplied with secure locking devices.

All isolating valves shall permit opening and closing against full and unequalised system pressure. If necessary, a bypass shall be provided to satisfy this requirement.

All valves shall be installed so that in event of plug or stem failure, valve will not close. Cast iron valves will not be accepted.

All pumps and compressors supplied shall be of recognized manufacturers and of adequate type and size to meet their functions.

They are to be supplied with all accessories and with electric motors suitable to allow continuous and safe operation under all conditions of the respective system.

All pumps and compressors shall be supplied with and mounted on a common base plate for pump and motor or compressor and motor respectively.

All elements subject to appreciable wear by water erosion shall be provided with easily removable and accessible wearing parts, permitting rapid and cost-effective repair.

Cubicles, boards and other enclosed compartments forming part of the equipment supplied shall be adequately ventilated and equipped to minimize condensation. If


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necessary, additional heaters shall be supplied for this purpose.

All ventilation openings shall be provided with louvres of corrosion-resistant metal.

5.2 Design and manufacturing tolerances

All components of these Francis turbines shall be subject to the tolerances prescribed in the ISO standards specified in the General Technical Requirements.

Tolerances shall not be cumulative.

Surface Finish of Water Passages

The surface finish of the water passages of Francis turbines shall be equal to or better than indicated in IEC standard 60193.

5.3 Design stresses

The Contractor’s standards for stress calculation and safety factors shall be applied throughout the design, or through checking of the existing equipment, particularly for parts subject to alternating stress, vibration, impact or shock.

If other criteria according to other international regulations apart from the mentioned design criteria should be considered, then the Contractor and the Employer shall mutually agree on these regulations.

Under normal operation, including any kind of shut-down, stresses in the materials shall nowhere exceed 50% of the yield point.

Under the maximum runaway speed conditions and under hydrostatic test pressure, corresponding stresses shall not exceed 75% of the yield point.

For constructions under water pressure, such as e.g. the spiral intake pipe, the uniaxial stresses at any point, shall not exceed 50% of the yield point of the material used under design pressure.

Upon the Employer's requirement, the Contractor shall present full information on the admitted stresses in any part of the equipment.

All components shall comply with earthquake conditions as indicated in the General Technical Requirements.

5.4 Materials

All materials shall comply with an approved standard (see General Technical Requirements).

All materials selected shall be most suitable for the intended use and shall be of a grade or class having guaranteed composition and properties according to the applicable standard. Generally, the Contractor is entirely free to use a better quality or more strict standard of acceptability for certain items, if he deems it necessary. Lower grades and less stringent prescription are not acceptable.

Basic requirements for materials are as follows:

5.4.1 Steel Plates for Fabricated Steel Structures

For fabricated structures exposed to water pressure, only fully normalized materials, quenched and tempered quality, of high resilience with low temperature ductility, and age-resistant shall be used.

The material shall be of a grade or class having guaranteed composition, properties and weldability and shall be ultrasonic-tested at the steel mill according to Class 3 of the ''Steel/Iron Terms of Delivery 072 - 77" (German heading: ''Stahl/Eisen-Lieferbedingungen 072 - 77'') of the ''Vereln Deutscher Eisenhüttenleute'' Table 2, Class 2 and Table 3, Class 2 or equivalent.

The finished plates shall be free from cracks, injurious surface flaws, laminations and any other defects. They shall have a workmanlike finish and shall not have been hammer-dressed. Remedying of plate defects by welding is not acceptable. Plates


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shall not be under their nominal thickness at any point. Plate material is subject to acceptance tests in the steel mill according to DIN 50 049 - 3.1 B or equivalent.

For mixed constructions (cast steel and plate steel), the Contractor shall examine the conditions of weldability and shall be responsible for transmitting to the steel foundry all instructions required for the selection of a compatible grade of cast steel.

5.4.2 Steel Castings

Steel castings of importance, in particular for constructions exposed to water pressure, shall be of a grade or class of an approved standard having guaranteed composition and properties, including low temperature ductility. The cast, cleaned, heat-treated and ready pre-machined casting shall be material-tested as specified in Clause 7.1 of this Section.

The test results must comply with specified composition and properties.

Steel castings must be completely free of cracks, shrink holes, „hot tears“, and shall not contain sand spots and inclusions, segregations, gas and blow holes, unfused chaplets and internal chills to a degree affecting their strength and durability.

Repair weldings of any kind may not be made without the consent of both the Contractor and the foundry; in case of doubt, the Employer's approval shall also be obtained.

Appropriate heat treatment shall be repeated after such major repairs. An accumulation of minor defects shall be considered as a major defect.

Regarding standard of acceptability of steel castings, reference is made to ASTH-B-71 and E-186 standards. The castings shall comply with Class 2.

Indications of imperfections derived from other methods of non-destructive testing shall also be considered. Such imperfections exceeding the nature of a local and tolerable imperfection may constitute a reason for rejection depending on careful investigation in conjunction with and on the basis of the respective design. Such indications are the following:

- all indications of linear or square dimension and local concentrations of several imperfections regardless of their individual size,

- all imperfections near surfaces, especially those to be machined or near highly stressed areas,

- ultrasonic indications larger than 6 mm dia. substitute fault size (6 m dia. AVG diagram) and indications of more than 10% back-wall-echo reduction.

A complete descriptive report of major faults, supplemented by sketches, photos and radiographs, surface prints and metallurgical test reports as the case may warrant, and the proposed repair procedure shall be Submitted to the Employer for review. The casting shall be clearly stamped with the heat number in such location as to be readily observed when the casting is assembled in a completed unit.

The extent of basic material tests required for steel castings is listed under Clause 7.1 of this Section 1.

5.4.3 Cast Iron

Cast iron will only be accepted for secondary parts: such as counterweights, supports, small bearings, etc.

5.4.4 Forgings

Forgings of importance (e.g. shafts) shall be made of vacuum-degassed steel and shall be forged thoroughly and throughout. Forging to shape, heat treatment (quenched and tempered, annealed or normalized as required) and rough machining shall be completed previous to material testing; results thereof must comply with specified compositions and properties.


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Forgings must be flawless, completely free from cracks and flakes, and shall not contain any other imperfection such as porosity, non-metallic inclusions, segregations, hard spots and residual tensions to a degree affecting their strength and durability.

Regarding the standard of acceptability of forgings: cracks, flakes and excessive hydrogen content as well as noncompliance with specified composition and properties constitute reasons for rejection. Further all imperfections as detected by non-destructive testing (dye check, radiographic or ultrasonic inspection. etc.) exceeding the nature of a local and tolerable imperfection may constitute a reason for rejection depending upon careful investigation in conjunction with and on the basis of the respective design.

Such indications are the following:

- all indications of linear or square dimension and local concentrations of several imperfections regardless of their individual dimensions,

- all imperfections near the forging surface, especially axial bores,

- ultrasonic indications larger than 5mm in diameter substitute fault size (5 mm dia.

AVG diagram) and indications of more than 10 % back-wall-echo reduction

Furthermore, all indications of imperfection larger than 2.5 mm dia. substitute fault size (2.5 mm of AVG diagram) of ultrasonic inspection or similar indications of other methods are to be recorded for judgement.

The largest fillets compatible with the design shall be incorporated wherever a change in section occurs. All finished surfaces of forgings shall be smooth and free from tool marks.

The forging shall be clearly stamped with the heat number in such location as to be readily observed when the forging is assembled in a completed unit.

5.5 Welding of structures under water pressure

All welding shall be performed by the electric arc method, and automatic welding equipment may be used, wherever practicable.

Butt welds shall be performed by processes and procedures producing welds whose properties match those of the steel being joined as closely as practicable.

All butt welds of the spiral case shall be ground flush. Flush shall mean not below and not more than 1 mm above the plane joining adjacent plate surfaces.

Fillet welds shall be performed with low carbon electrodes or wires and by a procedure designed to provide maximum ductility and freedom from cracking in the weld and heat-affected zones.

The surface finish of the fillet welds shall be reasonably smooth and free from irregularities, grooves or depressions; weld beads shall be narrow, shallow, regular and symmetrical in shape. Weld metal of spiral case shall be ground-off up to 1 mm over the inside surfaces.

Butt welds and tee joint welds shall be full penetration welds developing the strength of the plates being joined and designed to provide maximum ductility and freedom from cracking in the weld and heat affected zones. Butt welds and tee joint welds shall further be welded from both sides, except when otherwise shown on the approved drawings. Weld metal originally deposited at the bottom of the weld groove shall be chipped or gouged to sound material prior to depositing the first bead from the opposite side of the joint.

The sequence of welding and tack welding shall be clearly indicated on the Contractor's drawings prior to submitting them to the Employer for approval.

Tack welds shall be chipped or gouged before welding.

Preheating shall be performed prior to and during tack welding and shall be


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maintained as a minimum temperature during welding.

Run-on and run-off plates shall be provided for all butt welds, except when approved otherwise by the Employer.

Striking of the arc on the penstock, scroll case or pressurized piping will not be permitted in any event.

All welding materials including electrodes used for the work shall be of the highest quality and, with the proper procedure, shall be capable of producing weldings to the demands of the Requirements.

Electrodes for manual welding shall be of the low hydrogen type.

All welding shall be performed by skilled welders possessing satisfactory experience and qualified in the particular welding procedure, welding position and steel being used. Welders will be considered qualified for a particular welding procedure, welding position and steel if they satisfactorily pass the qualification tests specified in Clause 7.1.2.1. of this Section.

For Specification of material and non-destructive testing of the weldings and requirements of acceptability, refer also to Clause 7.1.

5.6 Corrosion protection

For executing Corrosion protection of the equipment included in this chapter the general requirements as set forth in General Technical Requirements, shall apply.

All priming and painting material shall fulfill the requirements imposed by the site conditions, as well as the stresses to which the respective material is subjected during operation.

At the request of the Employer, painting samples for the different coats and colours shall be provided.

The equipment ready fabricated and machined in the Contractor's workshop shall be completely shop painted. For components with considerable field welding (spiral case), the Contractor shall supply details regarding the extent to which sandblasting and painting will be carried out in his workshop and at site after installation.

A properly equipped paint shop shall be set up at the site using specialist personnel, experienced and skilled in the preparation and application of protective coating under the conditions prevailing at site.

Anyhow, the Contractor has right to propose as alternative solution for corrosion protection a painting system based on contemporary technology with high penetrating paints and high content of non-ferrous filling, always keeping corrosion protection guaranty of nominally 10 years, but with agreed allowance for progressive rust index in time as per General Technical Requirements.

For some typical turbine components the paint system schedule shall apply:

Surfaces in contact with water Water passages, including turbine parts if not of nonferrous, stainless or noncorrosive material

Paint system C,

General technical requirements

External surfaces Portions of spiral intake pipe

exposed to air

Paint system A,

General technical requirements

Surfaces in contact with oil Governor sump, governor cabinet, oil tanks

Outside: paint system E

Inside: sandblasted, grade 3,

oil-resistant paint

Parts and fished surfaces to be left bright in service

To be protected against corrosion during transport and installation with one heavy coat of removable


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anticorrosive varnish

Pipes carrying water under over and low pressure

Inside: none

Outside: paint system A

Oil pipes Inside: picking

Outside: paint system E

Embedded oil and water pipes Stainless steel

Air and drain pipes Hot dip galvanized

Valves, nominal dia. smaller then 50 mm

Made of corrosion resisting material

Valves, nominal dia. bigger then 50 mm

Outside: paint system B

Handwheels of valves To be provided with chromium or nickel plating

Screw, nuts and washers exposed to water

Stainless steel

Miscellaneous chequered plating, frames, supports

Hot dip galvanized

6. SPECIFIC REQUIREMENTS FOR PARTS

The specific requirements indicated hereunder are in addition to and in completion of those arising from the Contractor's obligation to supply complete work and designs suitable to fullfil the performance and requirements of the complete supply covered by this Section 1.

6.1 Turbine

6.1.1 Turbine runner

The runner shall be of the Francis type and shall be of stainless steel type 13/4 (13% chromium, 4% nickel). The material shall have a high resistance to corrosion and cavitation and good weldability. A flange connection shall be provided for bolting the runner to the lower end of the turbine shaft.

The runner shall be capable of supporting its own weight, together with the weight of the turbine and middle shaft, when the runner shaft assembly is uncoupled from the generator shaft and lowered to rest on the discharge or bottom ring.

The design and construction of the runner shall provide sufficient clearance for adjustments.

The torque transmission from the runner to the turbine shaft shall be by means of reamer bolts. In this case, for the attachment of the runner to the shaft, special coupling bolts shall be provided.

The runner disc shall be machined and bored to center on a main projection at the end of the turbine shaft to fit tightly to the coupling flange, thus assuring proper centering and alignment of the runner.

Removal of the runner shall be made from upper side. The coupling bolts shall therefore be designed in a manner allowing an easy removal of the runner.

The surfaces exposed to water shall be accurately machined and grounded and shall be free of any manufacturing imperfections which might cause cavitation pitting.

The mechanical and nondestructive material tests to be carried out on the runner are stated under Clause 7.1 of this Section.

Minor cracks and other defects, found by the material tests to be performed immediately after casting in the workshops of the foundry, shall be chipped and


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grounded to sound basic metal and the resulting hole carefully refilled by welding. No repairs to the runner casting shall be made unless approved by the Employer. A careful record of all repairs done shall be kept on drawings made expressly for such purpose. Major defects in the casting that will impair the usefulness of the casting will be sufficient cause for rejection.

After the runner has been completely machined and finished, it shall be subject to further inspection, again in accordance with Clause 7.1 of this Section. A complete record shall be kept of all minor repair weldings necessary during the final grinding operation. Each finished runner (with wearing rings attached) shall be carefully statically balanced. All runners in the power plant shall be interchangeable, without any adjustments.

6.2 Wearing Rings

At areas of small clearance between runner and stationary parts of the turbine and at the runner crown easily removable stainless steel wearing rings shall be provided and fastened by screws secured by tack welding.

Stainless steel selected for the wearing rings shall be of a different hardness the turbine runner in order to prevent galling or tearing of the metal in case of friction. Fastening screws or bolts to be of Allen type.

6.3 Turbine and middle shaft

The shafts shall be an integral carbon or alloy steel forging properly heat treated.

Their dimensions shall be sufficient to rate at any speed up to full runaway speed without vibration or objectionable distortion.

A removable and renewable stainless steel sleeve shall be provided where the shaft passes through the packing box in the head cover: sleeve accurately machined and polished and secured to shaft. Suitable oil and water deflectors shall be provided between guide bearing and turbine shaft seal.

The upper coupling flange shall be complete with a removable protection cover for the coupling bolts.

The lower coupling flange (turbine shaft) for the attachment to the runner shall be supplied complete with the necessary coupling bolts and nuts. With respect to the design of the coupling between runner and coupling flange of the turbine shaft, the remarks made under Clause 4.1 of this Section 1, shall apply. The locking of the bolts shall be made by extension of the bolts within their elastic limit. The respective calculation shall be submitted to the Employer’s for approval.

The device for the measuring of the coupling bolts elongation shall be included in the supply.

Upper and lower coupling flanges shall be integrally forged with the shafts.

Turbine shaft shall be accurately machined throughout its length and polished where it passes through the guide bearings.

The shafts shall be bored through the center of the shaft to ensure the passage of air below turbine runner.

For the shutdown of the unit in case of overspeed, the necessary provisions shall be made on the turbine shaft to accommodate the overspeed device.

The runout of the shafts shall be checked initially in the Contractor's workshop.

The fitting and final alignment of the shafts shall be performed at site during erection. Tolerances and procedure for shaft runout in the workshop and at site shall conform to NEMA Publication No.MG 5.2 - 1972 "Standards for Vertical Hydraulic Turbine Generator Shaft Run Out Tolerances".


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6.4 Turbine Guide Bearing

The turbine guide bearing shall be of the self-lubricated type, located as near the runner as possible consistent with convenient access to the shaft seal, and shall consist of a bearing support or housing and segmental type shoes. It shall permit axial movement of the shaft necessary for adjusting the thrust bearing and for clearing the centering portions of the coupling.

The bearing housing shall have removable top cover plates to prevent dirt or foreign particles from entering the bearing.

The sliding material of the guide bearing segments shall be made of white metal – „Babitt“.

The bearing housing shall be made of cast steel, or welded plate steel, split vertically and rigidly bolted together, and be designed to support the bearing shell rigidly and transmit the load to the head cover. The bearing housing shall have radial clearance in the head cover to permit adjustment for precise centering.

The bearing shall be capable of operating continuously without injury at any speed from 40% to 110% of the rated speed; for half an hour at any speed from 110 % of the rated speed to the maximum runaway speed specified. Furthermore, the bearing shall be guaranteed for correct operation during 15 minutes without water circulation, if starting from normal service temperature is envisaged.

Lubrication and cooling of the guide bearing shall be effected by oil-circulated through it. If auxiliary cooling of the lubricating oil is necessary, suitable heat exchanger shall be provided through which cooling water can be circulated, together with a cooling water pressure gauge and the necessary water piping. The heat exchanger shall be designed for safe operation with a required water pressure. The heat exchanger shall be shop-tested at the double maximum operating pressure. A flow relay with independent ungrounded contacts for interlocking with the automatic starting sequence and to sound an alarm on low flow shall be provided in the cooling water discharge line.

- One (1) oil level gauge, with two (2) sets of electrically independent contacts for shutdown and signalling,

- One (1) thermometer bulb embedded in the antifriction metal of the bearing, and a dial type contact thermometer (with at least two contacts) for mounting on the housing,

- Two (2) standard Pt100 resistance temperature detectors shall be embedded in bearing at the point of expected maximum temperature, for continuous indication and recording of bearing temperature.

All oil piping shall be supplied with the turbine and shall be of seamless copper type, with solder joint fittings, and bronze or brass valves.

The bearing design shall prevent water from entering the lubricating system and there shall be no appreciable loss of oil by leakage or by overflow from any part of the oil system under any condition of normal operation.

6.5 Spiral Casing and Stay Ring

The spiral casing shall be made of steel plates and the stay ring of cast steel.

Both spiral casing and stay ring shall be fabricated in a minimum number of sections practicable for shipment and handling, to suit the conditions for access, transportation and erection.

The spiral casing shall be provided with a sufficient number of levelling bolts or jacks, lugs and tie rods for supporting and holding the case during concreting.

The stay ring shall be supplied fully machined and its sections prepared for bolting together at site.

The stay ring shall be provided with uniformly spaced vanes, positioned to best meet


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efficiency requirements, and with machined flange for connections with upper and lower cover (head cover and bottom ring).

The water passages of the stay ring shall be smooth and free of irregularities. The internal surface finish of the stay ring, including any welds shall be 6 microns or finer.

Hydrostatic test pressure test

After the spiral casing has been assembled on permanent foundations at site, it shall be filled with water and subjected to an internal hydrostatic test pressure of 75 bar, lasting at least one hour. The necessary test ring for closing the stay ring openings, as well as the pressure test cover for the spiral casing inlet and other blank flanges and taps necessary to close the various openings on the spiral casing for pressure test, shall be provided by the Contractor once for both turbines and be delivered to the site with the first turbine.

The necessary pump, valves, gauges, piping and water to carry out the hydrostatic pressure test shall also be provided by the Contractor.

The design stresses during hydrostatic test pressure shall remain within the limits referred to under Clause 5.3 of this Section 1.

6.6 Head Cover, Bottom Ring and Discharge Ring

The covers and rings shall be fabricated of welded steel plates or made of cast steel and designed in least number of sections practicable for handling, shipment, and erection at site.

The head cover shall be designed to transmit to the stay ring the total bearing forces from the lower guide bearing including all hydraulic loads with a minimum of deflections and of concentrated stress under most severe service condition.

The head cover shall incorporate the upper guide vane bearings, seals and facing plates and accommodate the bearing surface for the guide vane operating ring.

The discharge ring will be bolted with the stay ring and will be provided with a welded connection for the draft tube cone. The bottom ring will be integral with the discharge ring. A shoulder shall be provided on the discharge ring or draft tube cone for supporting the turbine runner and shaft for erection purposes.

The bottom ring shall have incorporated bosses with bushings accurately bored to receive the guide vane stems. All bearing surfaces, guide strips, bushings and washers or other surfaces having relative motion shall be of bronze, other suitable antifriction metal or synthetic material, and shall be accurately fitted and replaceable.

The under sides of the head cover shall be designed to minimize friction and vortex losses in the space between the runner and the head cover, and the space shall be adequately drained to prevent excess water pressure under the head cover or excessive thrust on the top of the runner.

The head cover and bottom ring shall be provided with renewable stainless steel wearing rings at the location of the runner seal, as well as distributor facing plates. Provision shall also be made for checking the runner clearance without dismantling, preferably by feeler holes.

Drainage of the head cover top surface shall be, preferably, by gravity through stay ring.

A vacuum and pressure manometers shall be provided and connected to the head cover to permit measuring the pressure between the head cover and runner.

6.7 Draft Tube Cone

Draft tube elbow and concrete part will be kept, while draft tube cone will be replaced. The Contractor shall be responsible for adjusting the new draft tube cone into existing draft tube. The guarantees of turbine output and efficiency of the turbine shall include any effects of the entire draft tube (new designed parts and existing one).

The draft tube cone shall be fabricated of steel plates in a minimum number of


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sections practicable for shipment and handling, to suit the conditions for access, transportation and erection indicated in General Technical Requirements.

The draft tube cone shall be provided with manhole 600 mm diameter.

6.8 Shaft seal

6.8.1 Main shaft seal

The Contractor shall supply a shaft seal, a maintenance seal, and a seal water supply system.

Design

The shaft seal shall be of the radial or axial sliding ring type, preferably a combination of labyrinth type and axial sliding ring type. A packing gland or stuffing box is not acceptable. The shaft seal shall prevent entering of water from the head cover into the guide bearing. Special attention shall be given to the conditions when the turbine is at a standstill under maximum tailwater level. The sealing elements have to be easily replaceable without dismantling the turbine shaft and turbine bearing.

The seal shall be designed so that quick and easy inspections, adjustment and exchange of worn parts are possible. Suitable combinations of corrosion resistant materials shall be used so that the axial movable parts cannot become jammed due to oxidation, deposit of solid elements carried along by the water, etc.

The design shall include suitable precautions against contamination of the guide bearing oil due to a malfunction of the shaft seal.

The Contractor shall specify and supply all instruments necessary for safe operation and monitoring. However, a suitable sealing wear indicator shall be provided at an easy accessible place on the head cover. It shall be equipped with a limit switch.

Material of seal’s housing will be such that it eliminates the process of electrochemical corrosion caused by shaft current from the generator.

Appropriately cleaned water is supplied for the shaft seal. The Contractor shall determine the required level of sealing water consumption depending on the construction of shaft seal applied.

6.8.2 Maintenance shaft seal

A separate maintenance seal shall be provided to prevent inlet of water from the tailwater side to the above operational seal during turbine maintenance. Maintenance shaft seal shall be actuated by compressed air and interlocked with the generator brakes, in such manner that it can be engaged only when the brakes are engaged.

The maintenance seal shall be arranged in the lowest part of the head cover below the main shaft seal. It shall consist of an elastic ring which, when pressed against the non-rotating shaft flange, seals the space of the shaft seal against the maximum tailwater pressure stipulated in Clause 1.2 of this Section 1.

6.9 Guide Vanes and Operating Mechanism

All guide vanes shall be interchangeable and independently adjustable.

The gate mechanism shall have ample strength to withstand maximum load imposed by most severe transient operating conditions.

The guide vanes shall be designed to move towards closed position, in event of loss of turbine governor oil pressure.

The leakage through the closed guide vanes shall be kept at a minimum, if necessary by adoption of special sealing faces on the vanes.

The vane shall be fitted with watertight seal boxes, preferably replaceable with minimum dismantling of the gate mechanism.

The operating mechanism consisting of operating ring and levers shall be of steel, fitted with renewable wearing parts and an efficient lubricating system.


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The guide vanes will be made by casting of high-quality alloyed stainless steel (with Cr 13% and Ni 4% content, or similar). The vanes shall be uniform in shape and their cross sections shall be such as to obtain a streamline flow of water with a minimum of friction and hydraulic disturbances during operation of the turbine.

Each guide vane body shall be provided with greaseless self-lubricated bearings and a water seal. All bolts and nuts for the seals shall be of bronze or stainless steel.

The guide vane regulating ring shall be made of welded steel plates and shall be of rigid design. The structure supporting the regulating ring shall be of adequate strength and stiffness to prevent excessive deflections of the structure or other parts when the vane regulating ring is subjected to unbalanced loads of one servomotor with the other servomotor blocked.

6.10 Guide Vanes Servomotors

Provide two oil pressure-operated, double-acting, hydraulic gate servomotors having a combined capacity to operate guide vanes in all positions at maximum design head, including pressure rise.

It shall be possible to adjust the characteristics of movement of the servomotors, such that the opening and closing times vary between ±50% of the values given in the Schedule of technical data.

Secure and rigid devices shall be provided to prevent unauthorized changing of the opening or closing times after commissioning.

Servomotor shall be supported on rigidly steel construction that will be embedded in concrete.

Devices for adjusting and aligning the servomotors shall be provided.

Materials: Servomotor cylinders shall be made of cast or fabricated steel, rings and foundation parts of cast iron, cast steel or welded steel plate; pistons cast steel or iron, each piston with minimum of three cast iron rings per piston to prevent leakage of oil along piston.

Provide adjustable means for retarding rate of closure at closing end of piston stroke and a gate stroke indicator with pointer on one servomotor.

Adjustable mechanical, electrical or electronic connection to governor restoring mechanism at one servomotor cylinder shall be provided.

6.11 Overspeed measuring devices

An overspeed device mounted on the turbine shaft for the shutdown of the turbine generator unit in case of excessive overspeed shall be provided.

This device shall have hydraulic action on the governor oil pressure system and thus initiate the closing of the guide vanes.

The device shall be adjustable within a certain range above the theoretical maximum load rejection speed and be equipped with the necessary oil pipes and isolating valves for the connection to the governor oil supply system.

6.12 Control and turbine instruments

The following control and instruments shall be supplied to be locally mounted on each turbine.

The devices and instruments given hereafter represent the minimum requirements. However, the Contractor is bound to provide a complete set of equipment for the perfect operation of the turbine.

a) Turbine Guide Bearing

Metal temperature:

- 2 resistance type temperature detectors located diametrically opposite

- 1 capillary contact type thermometer


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- 1 thermostatic relay

Oil Temperature:

- 1 resistance type temperature detector

- 1 thermostatic relay

- 1 capillary contact thermometer

Oil Level:

- 1 oil level float switch for high and low level

Oil Cooler:

- 1 water flow meter with contacts

b) Turbine Spiral Casing

Water Pressure

- 1 dial-type pressure gauge

c) Shaft seal

Water Pressure

- 1 dial-type pressure gauge

- 1 manostat switch

Water Flow

- 1 flow meter with contacts

Differential Pressure on Water Filter

- 1 manometer

6.13 Standard and Special Tools

6.13.1 Standard tools

Standard tools for erection and installation of the Plant will be supplied by the Contractor.

6.13.2 Special Tools and Equipment

The Contractor shall use his special tools and equipment during erection and is responsible to render them at the end of erection to the Employer for overhaul and maintenance purposes, in accordance with the General Technical Requirements.

Special tools and equipment lost or damaged during erection must be replaced or repaired by the General Contractor at his own cost.

The following special tools and equipment shall be supplied by the Contractor:

- Special equipment for the locking and dismantling of the runner coupling bolts.

A hydraulically operated equipment, including measuring equipment for coupling bolt elongation, shall be provided,

- 2 complete sets of all lifting equipment, such as electrically operated cranes, necessary for the assembly and dismantling of all turbine parts,

- All necessary devices and slings for the suspension of turbine cover, shafts, turbine runner, etc. All devices suitable for assembly and dismantling of all

aforementioned parts, as well as for easy moving by means of the above mentioned lifting equipment,

- special device, if possible, for lowering and lifting the turbine shaft with runner in case of dismantling by means of hydraulic jacks,

- special device for dismantling and erection of the turbine guide bearing in case of replacement of bearing segments


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- special tools and devices for dismantling and erection of the turbine shaft seal in case of replacement of sealing parts,

- device for changing guide vane shear pins,

- device for dismantling regulating levers,

- device for turning turbine shaft,

- other tools and equipment as far as deemed necessary by the Contractor.

In particular the following equipment is enumerated to the Contractor:

- Shaft lifting device,

- Shaft coupling tool,

- Head cover lifting device,

- Attachment for impact wrench,

- Monorail hoist for handling turbine parts,

- Inspection scaffold for runner,

- Dismantling tool for guide vane lock,

- Dismantling tool for guide vane lever and shear pin,

- Guide bearing shoe adjusting tool,

- Slings.

6.14 Cooperation with Generator Manufacturer

The Manufacturers of turbine and generator shall closely cooperate in order to solve all problems with respect to the entire turbine generator system. In particular, the following questions shall be treated by both Manufacturers:

- the turbine, middle and generator shafts shall be designed jointly, and Contractor shall be responsible for ensuring that the calculation of the

corresponding critical speeds of the shaft system, which shall be safely above the runaway speed, is coordinated between both manufacturers;

- size of shaft and shaft coupling shall be mutually agreed upon, and subsequently be approved by the Employer;

- the necessary gaps shall be provided for lowering the turbine runner, and respectively for lifting the generator rotor and thus allowing the placement or

removal of the thrust bearing segments;

- if deemed necessary, a common template and boring tool shall be supplied by

the Contractor and made available for the generator manufacturer to drill and machine the mating coupling flange of the generator shaft. All expenses

incurred for the transport of the template from one manufacturer's workshop to the other and vice versa shall be included in the contract price


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7. INSPECTION AND TESTS

7.1 Material Tests

The extent of material tests, the relevant test procedures and limits of acceptance are listed hereafter. Based on these requirements, the Contractor shall prepare a list enumerating all components of the supply to be tested and the corresponding tests to be carried out. The Employer, however, reserves the right to request further tests, if he deems such necessary.

7.1.1 Steel Plates (for Fabricated Constructions Under Water Pressure)

a) In the rolling mill:

- for each normalized plate:

at the head end: 1 tensile test, in the as received condition, transverse to the principal rolling direction

3 charpy V-notch impact tests at 0°C parallel to the principal rolling direction 3 charpy V-notch impact tests at 0°C transverse to the principal rolling direction

1 bending test

at the foot end: 1 tensile test as above

For steel plates with tensile stresses perpendicular to the surface, an additional tensile test in the stressed direction shall be performed. The rolling mill shall certify that the plate will be suitable for such tensile stress.

- Per heat 1 chemical analysis

In addition each steel plate shall be checked for:

- perfect surface condition

- variations in thickness

- Laminations, by ultrasonic testing using the screen pattern method as follows:

All plates shall be ultrasonically examined using the straight beam technique. Procedural details shall comply with the requirements of 'Stanl-Eisenlieferbedingungen 072", issued Dec. 1977, Table 2, Class 3 and Table 3, Classe 3 equivalent.

Stamping (each place panel to be stamped in accordance with DIN 17155 after works inspection). The stamped plate number and inspector's symbol shall remain visible on the inside of the shell plate.

b) At the Contractor's works:

Sample tests of the guaranteed chemical and mechanical properties of steel plate material shall be carried out at the Contractor's works or in an independent laboratory on at least l0 % of the steel plates. However, at least one test coupon shall be taken from each steel quality or grade.

On each test plate the following tests shall be carried out:

- 1 tensile test transverse to the principal rolling direction; in the as-received

condition.

- 1 tensile test transverse to the principal rolling direction in stress-relieved

condition (for steel

- quality of components which will be stress-relieved at the end of production).

- 3 charpy V-notch impact tests in the as-received condition at 0°C, parallel to the principal rolling direction.


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- 3 DVH (DIN 50115 - German Industry Standards) impact tests in strain-aged condition (10 E upset by compression and annealed at 250 *C for 30 minutes)

at 0°C.

- 1 bending test.

- 1 energy temperature diagram of the DVM test ductility for the strain-aged condition. The DVM values at 0°C of above may be incorporated.

- 1 energy temperature diagram of the charpy V-notch ductility for the as-received condition. The charpy values at 0°C of above may be incorporated.

Required test values:

Tensile strength: conforming to guaranteed values of the steel quality

Yield stress: conforming to guaranteed values of the steel quality

Elongation and reduction

of area: conforming to guaranteed values of the steel quality

Bend test: the test piece shall withstand, without fracture, being bent cold around a mandrel of a diameter not greater than two times the thickness of the test piece. The angle of bending shall be 180°.

The plate material shall have impact test values not less than 85 % of the average shown below:

Longitudinal Cross

Charpy V-notch at 0оC 0.7 Nm/mm2 0.5 Nm/mm2

Charpy V-notch at 0оC 20оC 0.35 Nm/mm2 0.35 Nm/mm2

DVM strain-aged a 0оC 0.5 Nm/mm2 0.4 Nm/mm2

7.1.2 Welding

(Weldings on fabricated structures exposed to water pressure or mixed constructions - steel plates/cast steel - under water pressure.)

7.1.2.1 Welder's Tests

Tests prior to manufacture: (refers to both shop welding and field welding)

Prior to commencing production welding all welders shall have, to the satisfaction of the Employer, completed test plates in the welding processes, welding positions, of joint types and steels corresponding to the production welding type they will be performing.

The test plates shall be cut out of the thickest normalized steel plate to be used on the pipe shell constructions. welders who will be engaged in welding quenched and tempered steel shall be qualified on test weldings of this steel quality.

All welders engaged to perform welding for the subject power plant shall pass the welder's qualification tests according to AWS 460 (American Welding Society). The welder qualification certificates shall be forwarded for approval to the Employer together with the welding drawings.

The Contractor shall submit a description of the proposed weld procedures for approval by the Employer one month prior to commencing the welding tests and the production welding.

The test plates required for the welder's qualification may also serve for the qualification of the proposed weld procedure.


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7.1.2.2 Welding Tests During Manufacture

Test during manufacture: (refers both to shop welding and field welding)

During production, tests on welded joints will be required. They may be on run-on or run-off plates or on test plates which meet as closely as practicable the production weld being checked and shall be performed in accordance with the welding procedure of the production weld.

On each test plate shall be performed:

- radiographic check of the weld,

- 2 bend tests (one transverse face and one transverse root test) according to DIN 50121,

- 2 tensile tests with parallel bars according to DIN 50125,

- 3 charpy V-notch tests in the cover layer at -20°C,

- 3 charpy V-notch tests in the heat transition zone at -20°C.

The frequency and location of the required testing will be determined by the Employer. The average frequency will be one test plate every 10 m of welded joints for longitudinal joints such as on pressure pipeline and spiral intake pipe.


- tensile strength: conforming to guaranteed values of the

steel quality

- bend test according to DIN 1605, sheet 4

- impact tests на -20°C: 5 Nm/mm2 (5.0 kpm/cm2)

No impact test value may be less than 85% of the above indicated average values.

7.1.3 Ultrasonic tests (during manufacturing

7.1.3.1 General

Longitudinal and circumferential butt joints shall be ultrasonically examined.

The extent of ultrasonic examination shall be agreed between the Contractor and the

7.1.3.2 Methods

The Contractor shall be free to employ any recognized ultrasonic method, such as AVG, provided that discontinuities can be accurately detected and located.

The Contractor is required to use approved procedures for ultrasonic examination.

When the Employer questions the adequacy of the Contractor's method, the Contractor shall be required to demonstrate to the satisfaction of the Employer that the method is capable of detecting and locating discontinuities in butt joints.

7.1.3.3 Calibration

If the AVG method is used calibration shall be per BWI or equivalent.

7.1.3.4 Test Preparation of Seam

For satisfactory execution of the test, the work piece shall be cleaned on the left and on the right side of the seam along a width of at least 200 mm with rotating wire brushes from loose scale, rust and other contaminations, weld spatters shall be removed by grinding or with chisel.

7.1.3.5 Evaluation and Judgement

All indications which are beyond 20% of the reference line will be ignored and shall


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not be recorded. Indications which are at the 20 S line or higher are examined so far that the shape, kind and position can be determined and judged exactly.

Discontinuities are unacceptable if the amplitude exceeds the reference level, and discontinuities have lengths which exceed:

a) 6 mm for t up to 19 mm, inclusive

b) l/3 t for t from 19 mm to 55 mm, inclusive

c) 19 m for t over 55 mm

Where "t" is the thickness of the weld being examined. If a weld joints two members having different thicknesses at the weld, t shall be the thinner of these two members.

d) Where discontinuities are interpreted to be cracks or incomplete penetration, they are unacceptable regardless of discontinuity or signal amplitude.

e) Any group of indications in line that have an aggregate length greater than t in a

length of 12 t except where the distance between the successive indication

exceeds 6L, where L is the longest indication in the group.

If the AVG method is used the following acceptance criteria shall apply:

a) Longitudinal Indications

nominal wall reportable reference max. permissible

thickness (t) mm defect EFG reference defect EFG

10-20 1,5 3,0

20-60 2,0 5,0

60 3,0 8,0

Reference Defect = Ersatzfehlergrösse = EFG

b) Transversal Indications

Reference defects of equal or no greater than 1.5 shall be acceptable.

7.1.4 Radiographic Examination

In addition to the ultrasonic testing, radiographic examination on 10 % of the welding Joints subject to head pressure shall be carried out (on shop welding as on field welding).

Particularly, T-joints (joints between longitudinal and circumferential welds) shall be subject toradlography. Also all repaired portions of welding joints shall be re-examined with radiography.

Only X-rays or gamma-rays with iridium 192 are allowed.

Independent of the result of the radiographic examination, all welds shall be repaired if the each joints of ultrasonic testing are determined as cracks, lack of fusion or root failures, or if the echo heights reach the reference level or exceed same.

Interpretation of radiographs tests:

Radiographs will be classified in accordance with the reference radiographs of the International Institute of welding. Welds of the classes specified as black or blue colours shall be acceptable. Welds of the class specified as green, brown or red colours shall be rejected.

The Employer reserves the right to demand additional radiography at the expense of the Contractor if in his opinion serious doubts exist regarding the quality of the execution of the welds. The films shall be submitted to the Employer for review and will become property of the Employer.

7.1.5 Other tests

The inspection and test plan to be issued by the Contractor shall reflect all necessary other examinations and tests the Contractor intends to apply.


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However, the Employer reserves the right to demand and apply other examinations and tests if he deems such to be necessary.

7.1.5.1 Shaft Forgings

The following tests shall be carried out:

- chemical analyses

- on test specimens each taken from both ends of the shaft:

- 2 tensile tests (axial and tangential)

- 3 impact tests (charpy V-notch at 0°C)

- ultrasonic inspection

- radiographic inspection (in case of doubt)

- liquid penetrant inspection of the ready machined work pieces

With respect to the standards of acceptability, judgement shall be made on basis of acknowledged good practice taking into consideration all regulations of standards, or the Specification of the Contractor, if approved.

7.1.5.2 Turbine runner

Inspection at the steel foundry:

Immediately after casting and heat treatment of the turbine runner, a careful examination at the steel foundry shall be carried out comprising the following material tests:

- magnaflux examination of the whole casting

- ultrasonic examination where practicable

- radiographic examination of the highly stressed parts

- mechanical material tests

The mechanical properties of the runner material shall be Verified by means of test samples taken from test material cast to the runner. Such test material shall be sufficient for at least three complete sets of test specimens to allow for the possibili ty of making good and subsequent reheat treatment, or reheat treatment to obtain the required mechanical properties. All test specimens shall undergo the same heat treatment as the component they represent.

The mechanical material tests shall consist of:

- chemical analyses

- 2 tensile tests

- 3 charpy V-notch impact tests at 0°C

- 3 charpy V-notch impact tests at -20°C (for information)


Tensile tests conforming to guaranteed values of the specified steel quality

Impact tests

Charpy V-notch 0.5 Nm/mm² ( 5.0 kpm/cm²) at 0°C

Inspections of the ready machined runner (at the Contractor's workshop)

Already machined turbine runner shall be subject to the following final inspections:

- Roughness tests of all ground surfaces of the runner blades. The roughness shall be 1-6 microns within 250 mm from the inlet and outlet edges respectively and 3.2 microns over the rest of the blades and water passages equivalent to N7 and N8


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of the ISO standard 1302 (l974), which can be checked with the grinding samples of the internationally recognized ''Rugotest No.2''

- Inspection for defects on the surface, to be detected by the dye penetrant method. As result of this inspection the following limits of acceptability shall apply:

a) Cracks: No superficial crack whatsoever will be tolerated.

b) Porosities: On both sides of all blades. No circular indications dia. 4 mm shall

be indicated.

No linear indications will be accepted.

No linear indications with circular spots will be accepted.

c) Unfused chaplets, sand spots and inclusions will not be tolerated on the

ground surfaces of the blades.

Inspection for invisible defects, to be detected by non-destructive test methods, such as ultrasonic or radiographic examination, whichever is practicable.

d) Cracks: No cracks (or defects having the aspect of a crack) will be tolerated.

e) Gas and blow holes: For the whole blade, the acceptable limit is represented

by plate A3 of the ASTM Radiographic Standards for Steel Castings.

f) Internal shrinkage: For the whole of the blade, the acceptable limit is

represented by plate C3 of the ASTM Radiographic Standards for Steel.

7.1.5.3 Cast Steel (Other than Francis Runners)

Steel castings of importance, in particular for constructions under water pressure, shall be carefully examined immediately after casting, and the following material tests shall be carried out at the steel foundry:

- magnaflux examination of the whole casting

- ultrasonic examination where practicable

- mechanical material tests

7.2 Workshop assembly and workshop tests

All parts of the supply shall generally be assembled at the Contractor's works to the extent necessary for inspections, testing and otherwise ensuring that they will function satisfactorily. Exceptions to this rule may be permitted, if approved by the Employer.

All parts shall be correctly dowelled and matchmarked to facilitate assembly at site.

At least the following parts of the turbines shall be assembled at the Contractor's workshop and be presented to the Employer for inspection.

- Assembly of turbine spiral case and foundation ring and check of perfect alignment of the various parts. The parts which are provided for welding at site

shall be tack-welded in the workshop.

- Complete assembly of internal parts of turbine, such as bottom ring, turbine

cover, guide vanes, control system, guide bearing and it’s housing.

The Contractor is obliged to obtain the Employer's approval of the procedure proposed in this context.

The following is required for each turbine:

- static and dynamic balancing of the runner and runaway tests according to the latest edition of the Standard DIN SIO 1940-1. Static balancing will be

performed for the runner and Shaft separately while dynamic balancing will be


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performed for the assembled runner and shaft (runner+shaft),

- complete assembly of governor cabinet, including pressure oil supply unit and

air tank, as far as practicable.

In the assembled condition, the following shop tests shall be performed by the Contractor, and witnessed by the Employer:

- dimensional test of all water passages, in order to verify similarity between

model and prototype, according to IEC Code No. 193,

- Guide vans have to operate in whole range because the demonstration of the

their operation and operation of whole guide vane mechanism can be requested,

- Demonstration of cracking of one of guide vane’s levers with design load. The tests should carried with equipment which can demonstrate real operating

conditions,

- Pressure test of the pressure oil system of governor, including servomotors

and nitrogen tank. The system shall be tested for one hour at double the normal operating pressure.

- Complete trial run and acceptance test of the electronic governor in conjunction with the pressure oil supply system and regulating mechanism in

order to verify as far practicable the performance indicated in this Specification. For these tests, the IEC Code 308 'International Code for Testing of Speed

Governing System for Hydraulic Turbine'' shall be applied,

- Complete electrical functioning test of the control panels for pressure oil supply

units and compressed air supply unit.

7.3 Model Tests

7.3.1 General

1) The Contractor has to provide a model completely homologous to the prototype turbine for the purpose of checking hydraulic design, in order to determine operational characteristics of the prototype, and to prove that the efficiency guarantees are met.

The Contractor shall supply all materials, equipment, instruments and laboratory required to build the model and to perform test’s measurements. The model will remain the property of the Contractor.

The turbine model shall be complete with spiral casing, stay vanes, guide vanes, runner, draft tube, and shall be modelled to enable prediction of prototype characteristics.

The model shall be homologous to the prototype from the inlet section of the spiral casing to the outlet reference section of the draft tube (facing tail water) in accordance with the latest revisions of IEC standard 60193: International code for Model Acceptance Tests of Hydraulic Turbines.

The model shall have transparent plexiglass elements to provide visual observing of cavitation at the runner and at the guide vanes.

Net head, regarding the model tests, will be calculated for following inlet/outlet sections:

Inlet section: just after the spiral case inlet, and

Outlet section: just before exit from draft tube.

Note: Part of draft tube from the beginning of draft tube elbow (beneath draft tube cone) up to draft tube exit shall not be changed. Contractor shall measure all necessary dimensions during field inspection, before model tests;


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2) The tests shall be carried out in Contractor’s laboratory or other accredited laboratory chosen by the Contractor under test conditions equal to those laid down in the aforementioned IEC Codes.

3) The model runner diameter shall not be less than 350 mm.

4) The model test head shall not be less than 10 m and the Reynolds’s number not less

than 4 106.

5) Witness tests should be done for the heads given in the table in Clause 1.4.2.

6) Detailed Procedure of Hydraulic Model Testing shall be subject of review and approval of the Employer, and shall, among others defined by IEC standard 60193, contain at least the following:

- proposal for exact distribution of simulated prototype heads within agreed number of simulated heads (in accordance with Clause 7.3.3: Turbine Performance and Efficiency Tests),

- detailed procedures of measuring devices, zero-calibration and intermediate checks during the model tests,

- proposal for repeatability of measurements in case of errors or special Employer’s request,

- procedure for initial defining of Reref and Δηref,

- model turbine Winter-Kennedy measuring procedure.

The Procedure shall also contain detailed description of his test stand facilities, methods of measurements, expected inaccuracies and instrumentations as well as details of the model design as required in Schedules of Technical Data.

Detailed program of Model tests will be agreed with the Employer after the Contract signing.

7) Calibration of the measuring instruments shall be performed at the beginning of the phase of the Contractor’s Internal Model Tests. The calibration maybe witnessed by the Employer.

The Contractor shall officially invite the Employer to witness the calibration at least 30 days in advance.

8) Phase of Model Acceptance Tests shall last for as per agreed Time Schedule of Model Acceptance Tests.

9) Scope of model tests shall comprise:

- checking of geometric similarity all parts which will be replaced,

- turbine efficiency tests,

- cavitation tests,

- axial thrust tests,

- determination of torque characteristics of guide vanes,

- runaway speed test,

- investigation of influence of aeration onto turbine behaviour (both efficiency

and pressure fluctuation),

- measuring of pressure fluctuation at guide vanes and draft tube,

- Winter-Kennedy calibration curves determination.

- control of gaps.

7.3.2 Checking of Geometric Similarity

Checking of the geometric similarity of the model and prototype is to be performed in


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accordance with the provisions of the IEC Codes.

Checking of the surface finish of both the model and prototype is to be carried out in accordance with IEC standard 60193 under consideration of ISO Standard No. 1302 (1974).

7.3.3 Turbine Output and Efficiency Tests

The complete characteristics of the turbine in terms of head, discharge, torque and speed in normal and abnormal modes of operation shall be determined in order to establish model efficiency and output in the turbine mode for the guaranteed net heads, and for use in transient speed and pressure studies. A complete hill diagram shall be developed. Number of simulated prototype heads will be five, whereas there shall be at least 10 guide vanes angles per each head. The heads shall obligatory include the ones from which the turbine weighted average efficiency shall be derived (as per Clause 1.4.2).

Scale up of model efficiency in accordance with IEC standard 60193, Annex F shall be calculated.

Guide vane torque for the complete operation range shall be measured.

During the model tests the index characteristics shall be established for turbine operation in order to determine position of Winter Kennedy piezometer taps.

7.3.4 Cavitation tests

Cavitation tests of turbine operation shall be performed on the same model in accordance with the first supplement to IEC standard 60193. The tests shall show the effect of submergence on turbine efficiency for the full range of operations. They shall also extend beyond the range of prototype operations as required to determine the margin of the condition at which a drop in efficiency occurs.

Visual observations of cavitations on turbine blades shall be recorded.

As critical value of turbine cavitation coefficient the value that corresponds to efficiency decrease of 1%, shall be adopted.

7.3.5 Axial thrust test

Axial thrust tests shall be performed together with turbine efficiency tests in order to establish whether the results remain within the guaranteed values when converted to prototype values and whether they were taken into account in the structural design of all affected components of the unit and civil construction.

7.3.6 Runaway Speed Test

A runaway speed test shall be carried out incidentally by to the turbine performance test, giving the maximum runaway speed with the maximum operating net head.

7.3.7 Influence of Aeration

Regarding the aeration of the central vortex essential for the improvement of operational smoothness at part load, the Contractor shall determine the additional necessary air pressure, discharge and arrangement of air injection equipment, incidental to turbine performance test.

7.3.8 Pressure Fluctuation at Guide Vanes and Draft Tube

Pressure Fluctuation at Guide Vanes and Draft Tube shall be measured.

7.3.9 Test Reports

Draft Test Report shall be submitted to the Employer, at least one month in advance of beginning of Model Acceptance Tests.

After completion of the Model Acceptance Tests as per the precedent Clauses, including additional tests (if any) that might be performed by mutual agreement, the Contractor shall prepare Turbine model Final Test Report, comprising all data, measurements and curves and make conversion and interpretation of the results with


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a view to prototype conditions.

The Turbine model Final Test Report shall include:

- description and drawing of test equipment; report of dimensional inspections,

calibration data of test instruments,

- turbine hill chart of the model for various guide vanes openings for the full

range of specified heads. The results shall include the head for the maximum turbine efficiency, even if this point should occur outside the normal operating

range,

- differential pressure in taps for Winter-Kennedy piezometers for turbine

operation,

- pressure fluctuation curves in draft tube,

- characteristic speeds during runaway speed,

- example of complete calculation for one measuring point (from electrical value,

over calibration curves to physical values at the model, as well as the recalculation of model characteristics to the main design, and physical

prototype’s dimensions),

- complete diagrams for energy characteristics of the turbine model,

- complete diagrams for energy characteristics of the turbine prototype,

- complete diagram of turbine cavitation characteristics,

- results of measurement of axial and radial forces,

- results of measurement of turbine performance for extreme small net heads,

- guide vane’s moment torque characteristics.

Turbine model Final Test Report shall be submitted for approval within 4 weeks after completion of Model Acceptance Tests.

7.3.10 Failure of the Model to Meet Expected Performance

Should the model tests or the operation of the model show that the specified requirements are not met or that the prototype would not meet the guaranteed performance and efficiencies, the Contractor is expected to make all the changes that the model tests indicate they will improve the prototype design in that case. The Contractor is bound to furnish new parts or to prepare a new model to obtain results that do meet all requirements. All expenses involved shall be born and pretesting paid by the Contractor.

In case of failure to fulfill some of the guaranteed parameters after the completed model tests, the Employer has the right to: allow the possible continuation of the test, conditionally accept the results of model tests (until confirmation after prototype tests) and / or terminate the contract.

Contractual penalties for non-fulfilment of the guaranteed characteristics are given in the Contractual part of this Tender Documentation.

7.4 Tests on Completion

Commissioning of the turbines shall take place after successful termination of erection and the issue of an ''Complete and Ready for Commissioning Certificate'' by the Employer.

Commissioning of the equipment shall be deemed to comprise three stages of tests:

- preliminary tests (dry tests): performed at the end of installation, prior to any rotation or admission of water, to ensure the completeness and correctness of

the equipment installed

- pre-commissioning tests: involving filling of water passages, initial run, no load

tests, without connecting the unit to the power system


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- performance tests: with the plant connected to the system with the purpose of ensuring safe operation and of verifying the guaranteed performance.

7.4.1 Pre-commissioning tests (Dry tests)

At least comprising the following items:

- inspection of the complete water passages of the turbine, including pressure

shaft and draft tube to ensure removal of all foreign or loose objects which might cause damage, verification of the measuring sections and tapping points

for acceptance tests,

- adjustment of guide vanes for uniform closure and sealing dry tests of

operating times of guide vanes. Calibration of scales for guide vane-opening,

- electric control of correct wiring and cabling of all control, alarm and auxiliary

power circuits,

- testing and setting of all relays, protective equipment and transmitters,

including calibration of the electric control equipment,

- operational tests of turbine governor, cooling water system, drainage system

and compressed air supply unit, which shall include the correct functioning of the switching over from service unit to standby unit, adjusting, setting and

checking the operation of pressure relief valves, safety valves, distribution valves, pressure switches etc.,

- checking of the cooling water circuits with appropriate control valves and preliminary measurement of the cooling water flow,

- preliminary adjustment of opening and closing times of guide vane operating mechanism,

- complete function test of governing equipment, simulating manual and automatic starting and stopping sequences, operation of pressure oil units,

checking of oil levels and pressures in regulating system, 24 hours continuous operation of oil pressure system,

- verification of oil, grease and water supply to all bearings and main shaft seal requiring lubrication and cooling,

- operation of generator braking system,

- verification of proper fastening of all manhole covers.

7.4.2 Commissioning tests (with water)

Commissioning tests will be performed in close cooperation and coordination with generator and electrical manufacturers, and at least comprising the following items:

- slow filling of turbine water passages, pressurizing the system, checking of

spiral case and guide vanes for leaks,

- Pressurizing of the spiral case and turbine though the by-pass valve,

- Function test of main inlet spherical valve in low pressure dead water,

- Checking of the protections system of the spherical valve,

- Initial run of unit, stepwise increase of unit speed up to rated speed with observation of temperature behaviours of bearings and shaft sealing, shaft

runout, deformation of covers and bearing supports, measurement of vibrations in accordance with IEC/ISO standards,

- check of operational behaviour of bearings under no-load conditions,

- check of generator braking system,

- governor test in speed no-load regime,

- function test of complete turbine governor equipment, manual and automatic


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starting and stopping sequence up to rated speed,

- increasing speed of unit up to maximum runaway speed with verifications of

shaft runout, clearances, vibrations and deformations (on Employer’s demand),

- adjustment and setting of safety devices and overspeed trip.

7.4.3 Performance tests

During load rejection tests, all necessary measures must be taken to ensure that the permissible values for the pressure and loads of the turbine will not be exceeded.

Such measures may include setting down the lower timing values (adjustments) to the turbine governor than designed. When the turbine governor or control devices are adjusted, the tests carried out prior to such adjustments must be repeated:

- Synchronization of the unit,

- Preliminary tests under load and load rejection, whereby measures the speed and increase the pressure for load rejections 25%, 50%, 75% and full load (100%).

The load will increase gradually and load rejection until will occur after each additional load up to maximal which is expected for the prevailing net head. At the end of each load rejection test, overpressure and overspeed data will be analyzed to ensure that the units does not exceed the prescribed safety limits for the next load rejection.

Following the acceptance test, the following turbine performance tests will be performed:

- Testing the proper functioning of the entire system of turbine governor for any possible operating regimes, and according to the relevant IEC standards;

- Load rejection tests to demonstrate guaranteed maximum pressure and transient speed values for load rejections at 25%, 50%, 75% and full loads (100%);

- Response testing with gradual addition of load with oscillographic measurement of deviation of frequency, increase of turbine output, speed, opening of the guide vanes, voltage, the excitation voltage and the excitation current to the maximum power, the size and the number of degrees will be decided later by considering the real conditions of by the Employer;

- Index tests (on both turbines);

- Turbine output test at rated head in order to confirm the guaranteed values,

- Full runaway speed test (at the request of the Employer);

- Hydraulic overload test for stationary condition and transient conditions, in order to confirm the guaranteed values.

All tests, as described above, will be carried out at the available head at the time of the commissioning of the unit. For heads other than the above test heads, for which tests will also be required, such tests will be organized at intervals to be agreed with the Employer.

These tests will be organized for all net heads and other conditions, although the latter will be held after the Defect notification period has expired.

The Contractor's obligation in respect of special guarantees, the confirmation of which has not been proved by the tests carried out until that period, will be extended in accordance with the same period.

7.5 Trial run

After successful completion of all commissioning tests and performance tests the unit shall be subjected to the Trial Run, under Contractor’s supervision and responsibility.

During this period, the Employer's staff will be fully trained for plant operation and


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maintenance i.e. any necessary staff training shall be completed.

The trial run shall last 30 days. Should one or more tests be postponed or cancelled by mutual agreement between the Employer and the Contractor, this should not affect the start of the trial run. This also applies in particular to tests performed at maximum head.

After satisfactory equipment operation during the Guarantee Tests (Item 7.6) and the completion of the Trial Run, the Taking Over Certificate shall be issued by the Employer. On the day of issuance of this certificate, the Guarantee Period lasting 24 months shall begin.

Should one or more tests be postponed or cancelled by mutual agreement between the Employer and the Contractor, this should not affect the start of the trial run. This also applies in particular to tests performed at maximum head.

7.6 Guaranteed tests

The details of the methods, to be applied at measurements on the prototype turbine, the conditions and performance of these tests at Site shall be agreed between the Employer, the Contractor. The Contractor shall prepare the separate programme and submit it to the Employer 60 days before commencement of the tests. The programme shall define the sequence of the tests, the equipment preparation, the scope and details of tests as well as the procedure to be followed.

All tests shall be led by professional and experienced staff of the Contractor, who shall also execute the tests for the equipment within the Contractor’s scope of Works.

Appropriate computer facilities, instruments including multi-channel recorders for the registration of transient operation conditions and other measuring equipment shall be provided by the Contractor. The said equipment shall remain the property of the Contractor.

Guaranteed turbine outputs (as per 1.3.2) will be performed with Index Tests. Should the results of these Site tests indicate that the guaranteed data are not fulfilled, the Contractor will repeat the tests. Also, the cost of such repetition shall be borne by the Contractor. If these tests are not successful either, all relevant consequences under the Contract shall apply.

The Tests on Completion shall be performed according to the latest edition of the following standards:

- IEC Recommendations No. 60041: »Field acceptance tests to determine the hydraulic performance of hydraulic turbines, storage pumps and pump-turbines«,

- IEC Recommendations No. 60545: »Guide for Commissioning, Operation and Maintenance of Hydraulic Turbines«,

- IEC Recommendations No. 60308: »Hydraulic turbines – Testing of control systems«.

Evaluation of the test results and preparation of the test report shall be made by the Contractor. The test report shall be prepared in draft form within two months after the tests and the final form one month after approval of this draft.

During design of turbines, the Contractor shall make the necessary provisions for testing. The relevant drawings and data shall be submitted to the Employer for approval.

The Employer shall have the right to appoint his expert(s) (one or more) or a recognized institution(s) to approve the test program, assist and supervise the Tests on Completion and to check and approve the test reports.

All tests, as described below, shall be carried out at the net heads available at the time of testing, as close as possible to specified ones. Tests shall be performed at intervals to be agreed between the Contractor and the Employer, and depending on the possibility of adjustment of net head available.


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7.6.1 Index tests

Guaranteed turbine output tests will be performed by means of Index tests, in accordance with IEC 60041, providing relative values of efficiencies on ten test points at and above 40 % to maximum guide vane opening at least at two (available) net heads.

7.6.2 Overspeed Site Tests

Overspeed Tests shall be performed up to particular speeds reduced with respect to max. runaway speed to compare the results with those obtained by model tests and to measure the vibrations (in line with Section 8) and shaft runouts in particular conditions.

The Contractor shall indicate method and measures to be taken during these tests. Finally the Employer and the Contractor (turbine and generator suppliers) shall agree upon them.

7.6.3 Noise Level Tests

After terminating the previously specified tests and equipment put in normal operation the sound level measurements due to the turbine and auxiliary mechanical equipment operation shall take place at the highest noise exposed location in the powerhouse.

7.6.4 Shaft run-out and critical rotation speed tests

Upon completion of the previously defined tests and equipment commissioning, measurements of the critical rotation speed, shaft run-out shall be carried out, in accordance with the requirements of points 1.4.6 and 1.4.7.

7.6.5 Vibration tests

Upon completion of the previously defined tests and equipment commissioning, turbine operation vibration level measurements shall be conducted, in line with the requirements of point 1.4.16.

7.6.6 Guide bearing tests

Upon completion of the previously defined tests and equipment commissioning, temperature rise and bearing losses measurements shall be conducted, in line with the requirements of point 1.4.17.

7.7 Trial Run

After successful completion of all Commissioning tests, comprising successful finishing of all activities described in the Clause 7.6, the unit shall be subjected to the Trial Run, under Contractor’s supervision and responsibility.

Trial Run of the unit shall be considered as a constitutive part of the Tests on Completion, prior to issuing of the Taking over Certificate and it will last for 30 days.

Trial Run shall be considered as a test of continuous operation.

Within the specified period of 30 days only short stoppages of the unit is envisaged, with approval of the Employer. During these 30 days maximum five stoppages will be tolerated as defined in the Contract.

During this period, Employer’s staff shall be made fully acquainted with the operation and routine maintenance of the turbine.

After a satisfactory performance of the Trial Run, the “Taking over Certificate” will be issued by the Employer. On the date of the issuance of the “Taking over Certificate” the Defect Notification period will begin lasting 24 months.

SECTION 1 – TURBINES - EPS

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Transcript of SECTION 1 – TURBINES - EPS