2a. ISI-A. PEMELIHARAAN DAN PERBAIKAN KAPAL-1-30

8/7/2019 2a. ISI-A. PEMELIHARAAN DAN PERBAIKAN KAPAL-1-30

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A. PEMELIHARAAN DAN PERBAIKAN KAPAL 1.

A. MAINTENANCE AND REPAIR OF SHIPSPEMELIHARAAN DAN PERBAIKAN KAPAL

I. MATERIALHull and their constructions in general are used the following materials:

1. Wood2. Iron/Steel3. Aluminum4. GRP/Fiber Glass5. Cement/Concrete

For many centuries ships were built from wood and construction techniques changed little. Next,

hulls built of iron were introduced.

Then, more than 100 years ago, steel started to replace iron and wood and major changes occurred

in ship construction. Subsequent developments have included the all-welded ship and the

investigation of material strength using notch toughness techniques to prevent brittle hull

fractures. Factors such as fatigue and corrosion have also become increasingly important.

By understanding the basic principles of material technology - appropriate material selection and

welding methods you will be able to conduct your inspections more specially. This book will not

make you an expert on materials and welding, but it will help you to inspect them more

effectively. You will find more information about the Non Destructive Testing (NDT), of

materials and welding in book Non-Destructive Examinations.


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Picture 5


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Metal Production

Steel production starts with the smelting of iron ore in a blast furnace to produce pig iron. The pig

iron is purified to produce steel using the open hearth, electric furnace, oxygen process or other

approved processes.

The objective is to minimize the non-metallic content of the steel. The tensile strength may be

altered by varying the percentage of carbon in the steel and by the addition of various elements

such as chromium, nickel, manganese, etc. Steel is subjected to heat treatment, such as

normalizing, etc., depending on the grade. The purpose is to produce steel having a fine-grained

structure. This improves its tensile strength, ductility and resistance to shock.

Aluminum production starts with bauxite ore, which contains roughly 56 per cent aluminum. The

bauxite is purified to obtain alumina, and this is reduced to a metallic aluminum. There is a

number of aluminum alloys in use, but these may be separated into non-heat treated and heat

treated alloys. The latter are subjected to a carefully controlled heating and cooling cycle to

improve the tensile strength. At present, most aluminum alloys used in shipbuilding are for the

construction of superstructures and where weight reduction is important, such as for high-speed

craft and naval ships. The advantages of using aluminum alloys are:

Reduction in top weight and so improved stability

Increase in deadweight Resistance to bending stresses Corrosion resistance Non-magnetic properties

The disadvantages are that it is more expensive to work and weld, and different coefficients of

expansion between steel and aluminum may give rise to a hogging condition.

Copper is rarely found as pure metal but is extracted from ores. Copper and copper alloys are used

for pipes and fitting mainly intended for use in pressured lines, for condensers and heat

exchangers, and for propellers.

Non-metalsNon-metallic materials are widely used in shipbuilding for various purposes. The many different

plastics in use have many different properties. Basically are lightweight, flexible, durable, and not

highly inflammable, have good insulating properties and are easy to fabricate. GRP, glass

reinforced plastic, was introduced in the 1940s for marine structural application such as

construction of life boats and laminate plastic bearings for rudder and stern tube. Other plastic

include nylon and polypropylene for mooring ropes, epoxy resin for engine foundation, plastic

piping for non-essential service, cable insulation for electric wiring, insulation for refrigerated

compartments, decorative laminates and fitting for the accommodation, and, last but not least,

carbon fiber reinforced plastics on high speed craft for parts of the hull, shafts, coupling, etc. You

will find more about non-metallic materials in other book, as well as in Ships Materials.


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Works approval

All materials and product covered by the standards and Rules may only be manufactured in works

approved by Class for this purpose. This includes mild steel and higher tensile steel plates and

sections built into a ship as well as all materials and components to be used in activities within the

Classification procedure. To be approved, the works must satisfy some specific conditions, proof

of which will normally be furnished during a factory inspection, and by submission of relevant

documents before the start of manufacture, e.g.

The will be equipped with installation enabling the materials to be expertly manufacturedand worked in accordance with modern technical practice,

They will have the necessary testing equipment and the skilled staff required for itsoperation in order to perform the tests specified in the Rules. Where individual tests have

to be carried out by outside bodies, the manufacturer shall entrust such tasks only to those

firms or institutes which also meet the aforementioned conditions and have been

approved,

The works will normally ensure by their own quality control arrangements that theproducts are expertly manufactured and processed and that they meet the specified

requirements. Testing carried out in Class presence will not absolve the manufacturer from

this liability. Any internal quality control systems must be independent of the management

of the production and processing departments. As part of their own internal quality control system, the works must keep a constant record

of the manufacture and testing of materials and products. Where required, the works must

demonstrate Class the properties of their product by preliminary testing of the procedure

and the product suitability.

Quality Assurance

If the manufacturer has established and maintains a quality assurance system conforming to ISO

9002 or ISO 9001, and submits a certificate to this effect which bears the accreditation stamp of

the certifying authority, the in general, this demonstrates compliance with the requirements.

The manufactures work will request approval in writing. Request must contain technical

information, such as: Materials and product for which approval is requested, including the method of

manufacture, guide values for the chemical composition, condition in which the materials

and products are to be supplied, properties and dimensions.

A list of the manufacturing installations and testing equipment used, together withdescriptions of the quality control system and details of the persons responsible for quality

control. Where tests are performed with external laboratories, their addresses and testing

facilities must also be provided. Such testing bodies are also subject to approval. This

condition is satisfied if the testing body is accredited under accredited institution.


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Elasticity

When a force or load is applied to a solid body it tends to change the shape of the body. When the

applied force is removed, the body will regain its original shape. This property of returning to the

original shape is termed elasticity. Should the apply force be large enough, the resistance offered

by the material will be overcome. When force is removed, the body will no longer return to its

original shape and will have become permanently distorted. The point at which the body ceases to

be elastic and become permanently distorted is termed the yield point, and the load required to

cause this is the yield point load. The body is then said to have undergone a plastic deformation or

flow.

Materials are tested to ensure that their properties such as strength, ductility, toughness, plasticity,

brittleness, malleability, hardness, etc. are suitable for the function they are required to perform.

Testing methodsThe properties most commonly used for design calculation and material acceptance are determined

from the tensile test. Specimens and procedures for tensile testing vary between different products.

Proportional and elastic limits, yield point and yield strength, tensile strength, elongation and

reduction of area, are other properties, which may be determined, if required.

The occurrence of brittle fractures in ship hulls during World War II stimulated and exhaustiveinvestigation to determine the causes these material failures. It was found that steel which

fractures in a ductile mode, with the absorption of a large amount of energy, will fracture in a

brittle mode with the absorption of a very little energy, when it is at a certain lower temperature.

The toughness properties of a material will be mainly determined by the most widely used and

empirically developed toughness test, the notched bar impact test. Further test have been

developed in the field of fracture mechanics, such as the drop weight test as well as other

specialized tests.

When a material is exposed to repeat cyclic loading at stresses below the tensile strength of the

material, it may fracture from fatigue. Fatigue is a complex phenomenon, which depends on

factors such as the material homogeneity, size effect, stress concentration, working environmentand order of loading of varying stresses, stress range, and overall design.

Fatigue testing uses a wide range of specimens up to full-scale models.

The bend test is a qualitative method of measuring ductility in which a test piece is bent around a

mandrel of a specified diameter.

The hardness of materials is generally determined by indenting the surface with an indenter.


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Manufacture

All materials will generally be manufactured by well-proven techniques, which ensure that the

required properties are achieved. Where new processes are to be employed, proof of their

suitability must be submitted. This will take the form of special procedure tests and presentation of

works documentation of tests performed, or of expert assessments by independent testing bodies.

In the case of steel, the well-proven techniques include the basic oxygen process or electric

furnace steel-making and continuous, ingot and mould casting. The chemical composition and

material properties as specified in the standards and Rules or in the relevant specifications for

materials and product must be controlled and verified. As a basic principle, the specified chemical

composition will be that of the melt, although the product analysis may be used in special cases.

The manufacturer will normally determine the chemical composition of each melt and will provide

the corresponding information to you.

The limit values that apply to the melt analysis are as specified in the standards and Rules or in

other relevant documents.

Heat treatmentThe products will be supplied in the prescribed heat-treated condition or in the material condition

as specified for the alloy concerned. If the final heat treatment is to be performed by the user, thecondition in which the material is supplied must be clearly stated in the relevant certificates.

All heat treatments, such as normalizing or quenching and tempering, must be carried out in

suitable furnaces, which are properly and efficiently maintained. The furnace must, at the least, be

provided with devices must be checked at regular intervals. If manufacturer intends to apply other

treatments in place of the prescribed heat treatments, they will first have to verify that the resulting

mechanical properties of the products meet the requirements.


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Defects

All materials and products must normally be free from defects, which would adversely-effect their

use or appropriate further working.

Insignificant surface defects, however, may be mechanically removed, provided that the

dimensional tolerances for these products are not exceeded. Material defect may be repaired with

welding only:

If this is permitted by the product specification

If you have given your consent, and

If the welding technique used has already been approved

All materials intended for the manufacture of welded structures must be weld-able by standard

workshop technique. If welding is possible only in special conditions, these will be determined in

agreement with Classs office and will be validated by a procedure test.

All products should be checked by manufacturer for compliance with specified dimensions and

inspected for possible defects. They should then be presented to Class.

For this purpose, the products must normally be in the prescribed as delivered or heat-treated

condition and must have a clean surface, prepared for testing, which is free from coating or other

protective media which impair the detection of defects. Unless otherwise specified or speciallyagreed, Class should perform a random test of the dimensions and surface finish as required. The

manufacturer should set aside products that do not meet the requirements beforehand.

Where products are manufactured in large runs by series-manufacturing techniques and using

continuous processes with constant, monitored conditions, Classs office may entrust the

manufacturer with the performance of some or all of the tests. This is subject to the condition that

the manufacturer has established and maintains a quality assurance system, e.g. in accordance with

ISO 9002 or ISO 9001. Approval of testing on the manufacturers responsibility is to be applied

for in writing to Classs head office.

Class may ask for additional tests if there is reasonable doubt as to the quality of a product. Note

that your office does not guarantee that all products, which have tested to the prescribed extent-fulfill, in all respects, the requirements in the standards and Rules or other relevant documents.

Class may reject products, which subsequently prove to be defective in use or during processing,

despite satisfactory previous testing. But, Class should perhaps contact their office first!

From the safety point of view, Classs office will normally reserve the right to extend the scope of

testing to materials and products not specially mentioned in the Rules.


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Product Identification and Marking

The manufacturer must have a system, which enable the product to be identified after every stage

of the manufacturing process and also be traced back to the heat. This system should be shown to

Class, if Class so request. Prior to acceptance testing, products must be provided by the

manufacturer, at the least one position, with the necessary marking.

Remember that the marking must agree with the details given in the works certificates or the

delivery documents.

The marking is normally impressed with a punch, unless this is excluded for materials with a

sensitive surface or which are too thin. In such cases marking may be done with low stress stamps,

paint, rubber stamps, adhesive stickers or electro engraving. This also applies to Classs own

office marking. If further processing requires the removal of existing marks, the manufacturer

concerned must apply these to a different area and must arrange for the transfer of Classs office

stamp, unless another solution is agreed. As a general rule, every product is to be suitably marked.

For small parts of the same type and size packaged together, and also for small steel rods and

sections packed together in bundles, Class normally-mark only the uppermost unit or attach a

strong tag.

Wherever possible, marks should be enclosed by a painted surface. In the case of forgings and

castings, the area to be marked should be bright machined. Specimens, and the product fromwhich specimens have been taken, are normally marked with Class specimen stamp. Products for

which individual tests of some kind are specified, e.g. tests of mechanical properties and surface

finish, internal pressure test and non-destructive testing, should be marked in Class presence with

Class acceptable stamp, provided that all the requirements have been satisfied.

Batch productsSteel plate, sections and rods, which are grouped into test batches, will be marked with the batch

stamp. (This procedure may vary between Class Societies). Approved material manufacturers and

suppliers may also apply this stamp. If, during subsequent tests or further processing, the tested

products exhibit defects or in some way no longer meet the requirements, the stamp should be

cancelled in a suitable way, e.g. by grinding.

If Classs office agrees, manufacturers who have a satisfactory, independent quality control

department may allow members of this department to apply the specimen stamp. Class must be

notified by the manufacturer of the names of the persons concerned and of the marks identifying

their personal stamps.


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Test certificate

For each consignment the manufactures will normally supply Class with a test certificate or

delivery specification containing the following details:

a). Purchaser and order number

b). Number and weight of the products

c). Designation of the material and condition in which supplied

d). Composition of the heat (or of the starting material, where applicable)

e). Method of manufacture

f). Result of mechanical tests if performed by the manufacturer

g). Test pressure, where applicable.

For the final inspection, all materials will be stamped or marked by the manufacturer in at least

one place with the following marks, as needed:

a). Material grade

b). Manufacturers mark

c). Item or heat number, or another mark enabling

The manufacturing process to be traced back

d). Specimen numbere). Date of test

f). Test pressure, where applicable

If necessary, the area receiving the stamp marks should be ground. Class will find more details in

Classs Rules and Instructions.


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Test Certificates and Documents

For testing purposes, the manufacturer has to submit the documents referring to the materials or

products to be tested. These documents will contain information such as:

Quantity, product type, dimensions, type of material, condition of supply and weight Name of purchaser together with order and job numbers Building project number or name or vessel, where known

Request, if needed.

When materials testing are left to the manufacturers, they will issue a relevant acceptance test

certificate.

Besides the information mentioned above, this also contains:

Method of manufacture, heat numbers and chemical composition Condition of supply with details of heat treatment Identifying marks Result of tests carried out on material.

If Class witnessed the tests and the specified requirements are fulfilled, Class has to certify the

results. This is normally done in the form of an acceptance test certificate.

If agreed the results may also be attested:

By confirmation by Classs stamp and signature of the test results on an acceptance testreport, i.e. joint certificate by manufacturer and Surveyor.

For products produced in large quantities and tested by heat or batch, by confirmation withstamp and signature on the manufacturers certificate, in token that the tests on the

consignment, in accordance with the standards and Rules met the requirements.

In addition to this, the manufacturer will stamp the certificates accordingly and will also confirm

that the products listed in the documents have been manufactured in accordance with the standards

and Rules. In case of doubt about the procedure to be followed, Class can always call their office.


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1. Metallic Materials1.1. Steel Plates and Rolling Products

Picture 6

The properties of plain carbon steels depend on their chemical content and microstructure. In

addition to carbon, these steel contain manganese, silicon, phosphorus and sulphur. Minor

amounts of other elements may also be present. The higher working stresses permitted with higher

strength steels allow for reduction in section thickness and weight. A major difference between

these steels and the plain steels is that the higher strength steels have special additions such as

aluminum, niobium, vanadium, etc. These promote micro structural improvements andstrengthening.

This item contains general information to be applied in the manufacture and testing of hot-rolled

plates, strips or flats, sections including hollow sections, rods and bars. Steels conforming to

national or international standards may be also used, provided that they satisfy the minimum

requirements of the Rules. In addition, an approval test on products selected for the purpose will

normally be required.

Tolerances

Plates, strips and wide flats may be delivered with or without the allowed minus tolerances. Where

standards or Rules do not give specifications, the permitted minus tolerance should be agreed

when the order is placed. Local depressions due to flaws and grinding marks can be ignored,provided that they do not exceed the allowed tolerances.

For sections and bars, you should ensure that the standards have been applied.

The specified mechanical properties must be verified with an appropriate range of tests. Where

special properties, such as resistance to inter-crystalline corrosion, resistance to brittle fracture, or

high-temperature strength, are prescribed for certain groups of products, these must be validated

by appropriate tests, as necessary.

The chemical composition as specified for the steel grade will be shown in the certificate.


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TestingAt least one tensile test specimen is to be taken from each test batch as defined in the standards

and Rules. The Rules also specify the position from which test sections should be taken for all

types of plates, bars, and rolled products. The test sections will normally be taken from products

only after the final heat treatment. Where further hot working is needed, and where testing of the

properties in the final heat-treated condition is required, the test sections may be subjected to

separate heat treatment.

Products for high temperature applications require a hot tensile test performed on at least one

specimen from each heat at the specified test temperature. For steels conforming to recognized

standards with already proven mechanical characteristics, this test is not required.

Notch impact and ultrasonic tests should be performed in accordance with the recognized

standards. Testing staff must be adequately qualified and Class should see proof of this. Class may

take part in the tests if Class wish.

Where specimens subjected to tensile or impact testing fail to meet the requirements or where, in

the impact test, one value is less than 70% of the required average value, the re-testing procedures

may be applied before the unit test quantity is rejected. This also applies where specialcharacteristics such as shear-strength, ductility, etc fail to meet the requirements.

Special requirements

The special requirements associated with steels for steam boilers and pressure vessels, which

apply to flat products, plate and strips made from high-temperature ferritic steels have led to the

development of special rules for such services.

The Rules requirements for steels intended for the construction of cargo tanks apply to flat

products made from fine grained structural steel, high strength, quenched and tempered fine

grained structural steel, nickel alloy, and austenitic steels intended, e.g. for the manufacture of

cargo tanks for carrying liquefied gases.

The major structural application of corrosion resistant steels is to provide a surface that is resistant

to chemical action from a liquid cargo. These standards and Rules also apply to flat products,

sections and bars made from corrosion resistant steels intended for fabrication of cargo tanks of

chemical tankers, pressure vessels, etc. which require chemical stability in relation to the cargo or

operating fluid. Sleeves of rudderstocks, rudder pintles, propeller shafts, etc. which are required to

be seawater resistant are also included. Steel plates clad with cladding materials made of stainless

steels are dealt with separately in the Rules.

In addition, there are Rules applying to plates, strips, wide flats and shapes made of line-grained

structural steels for which enhanced deformation properties in the direction of the thickness are

required.


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1.2. Steel Pipes and Tubes

Picture 7

This item covers the general rules to be applied in the manufacture of seamless and welded steel

pipes. The scope also embraces all pipes used in the construction of steam boiler, pressure vessels

and equipment, as well as for pipelines, accumulators and pressure cylinders. Steel pipes forstructural applications, pipes which are individually manufactured and welded, such as masts,

crane posts, pressure vessel shells, etc., should also comply with the requirements for welding.

Pipes may be designated either in accordance with the relevant standars or with the symbols

shown in the Rules. In the latter case, pipes made of carbon and carbon-manganese steels must be

indentified by their minimum tensile strength and by the added letters denoting high temperature

steel or denoting steel tough at sub-zero temperatures where applicable. Alloy pipes, with the

exception of the austenitic grades, will normally be identified by symbols denoting their alloy

content.

In addition, if welded pipes are manufactured, the characteristics and the required quality of the

welded seam must be verified by a procedure approval test determined on a case-to-case basis.The test of suitability will also be carried out inthe case seamless pipes, if they have to meet

special requirements, e.g. in respect of their impact energy at low temperatures of their hight-

temperature strength characteristics.

The chemical composition of the pipe material and pipe dimensions and tolerances must comply

with the relevant standards and Rules. The ends of pipes must be cut off perpendicular to the pipe

axis and must be free of burrs. Apart from pipes that are delivered in coils, all pipes must appear

straight to the eye. All pipes must be leak-proof at the specified test pressures.


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Testing

For testing, pipes will normally be grouped by steel grades and dimensions, with alloy steel pipes

also grouped by heats, into test batches. Where welded pipes are concerned, a pipe is normally

considered to be a cut length of not more than 30 m.

For tensile tests, two pipes each are to be taken from the first two test batches and one pipe each

from very subsequent batch. For a consignment of 10 pipes or less, one pipe will be sufficient.

Normally longitudinal test specimens will be taken from the sample pipes. Where the diameter is

200 mm or more, test specimens may also taken transverse to the pipe axis. From welded pipes

additional test specimens are to be taken transversely to the welded seam. The weld reinforcement

should be machined off over the gauge length.

Non Destructive Testing (NDT)

The manufacturer should inspect the finish of the inside and outside surface of each pipe. The

diameters and wall thicknesses will also be measured. The pipes will then be submitted to Class

for final testing. The pipes will be subjected to NDT to the extent specified in the standards and

Rules. Where possible, the NDT will be continuously performed, using ultrasonic or eddy current

methods. Fusion-welded pipes may also be subjected to radiographic inspection. Test equipment

for continuous inspection of pipes must be regularly calibrated using pipes with artificial defects.

Class may ask for a demontration of the equipments efficiency.

The manufacturer must test all pipes for leaks by an internal pressure test or by suitable NDT

methode. For thin-walled pipes with large outside diameters, the test pressure must be limited so

as to ensure that the yield strength is not exceeded. Exceptionally, where testing with water is not

possible, another testing medium may be agreed. If NDT is used it must be able to cover the whole

circumference of the pipe and the methode must conform to a recognized standard.

Marking

Marking will normally be applied with punches unless these are likely to cause damage in which

case another method must be used e.g. by coloured imprint, electrical engraving or rubber

stamps.

The manufacturer must also certify that all the pipes have been successfully tightness tested and

undergone NDT and a test of resistance to intercrystalline corrosion, where applicable.


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1.3. Forging

Forgings are normally used both for applications where the shape of the product is comparatively

simple, such as anchors and rudder stocks, and for more complicated items such as crank shafts,

etc. where better homogeneity is required that can be obtained by casting. Other simple items cansometimes be handled by a rolling process.

This item covers the general rules to be applied in the manufacture and testing of forgings. These

also apply to rolled steel bars, where these are to be used in place of forgings for the machining of

shafts, shanks, pins and similar parts.

Given a reasonable machining allowance, workpieces should as far as possible be forged to the

final dimensions. Excessive machining to give the forging its final shape is not permitted as this

may affect its characteristics, e.g. by laying open the core zone. The degree of deformation must

be such that the core zone of the forging undergoes sufficient plastic deformation. In any case the

plastic deformation must be such as to ensure soundness, uniformity of structure and satisfactory

mechanical properties.

Annular and hollow shapes are to be produced from sections cut from the ingot or bloom steel,

which have been suitable, punched, drilled or trepanned before the parts are rolled or expanded

over a suitable mandrel. Where two or more forgings are to be welded together, details of the

welding methods should be submitted for approval. A welding procedure approval test may be

necessary.


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All forgings must be suitably heat treated according to the material for obtaining a fine grain,

homogeneous structure, as well as the required mechanical properties. All hot forming operations

must be completed prior to the final heat treatment. If for some reason, a forging needs reheating

for a further hot forming operation, then the final heat treatment must be repeated. If a forging is

subjected to hot or cold straightening after the final heat treatment, subsequent stress relief heat

treatment to remove the residual stresses may be required.

Forgings, whose section will be substantially altered by machining after the forging operation,

may only be quenched and tempered after they have undergone adequate rough machining. If the

prescribed heat treatment is to be replaced by an equivalent temperature cycle during and after the

hot forming process, appropriate test must be performed to prove that the method is equivalent.

Inspection

The manufacturer must inspect each forging for surface finish and compliance with the

dimensional and geometrical tolerances and must then submit the forgings for final inspection.

The inner surfaces of hollow forgings and bores are to be included in these inspections. Surface

defects are to be removed. Where necessary this condition will be achieved by pickling, local

grinding, shot or sand blasting, cleaning with wire brushes or by chemical means, unless the parts

are submitted in the rough machined condition. If the surface condition suggests that welds havebeen carried out on the forging, you may demand local etching to reveal possible welds.

Any NDT requested must be performed by the manufacturer or finishing workshop, using suitable

equipment, test facilities, and qualified test personnel. The result must be certified and state the

technical details of the test. The manufacturer must establish a monitoring system enabling all

forgings to be traced back to the original heat, and this should be demonstrated on request.

The rules and standards contain more information about forgings made of unalloyed and low alloy

steels intended for the manufacture of components and structural parts in machine construction

and shipbuilding, e.g. shafts, piston rods, connecting rods, rudderstocks and heel pintles. This also

applies to rolled round bars for the manufacture of shafts, pins, tie-rods and similar components,

which are given their final shape by machining.

Forgings for crankshafts, gears, boilers and pressure vessels, process equipment and pipelines are

special cases. Special rules also apply to steel forgings tough at sub-zero temperatures and high-

strength, quenched and tempered steel forgings which are intended for cargo and processing

equipment on gas carries, e.g. flanges, valve parts, weld-on and socket welding parts, as well as to

forgings made from corrosion resistant steels.


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1.4. Cast Steel

Heavy structural members with complicated shapes, such as rudder parts, are generally producedas steel castings. Castings are likely to be non-homogenous, and fabrication may reveal conditions

such as cracks, and inclusions, gas holes and internal shrinkage.

This item covers the general requirements to be applied in the manufacture and testing of steel

testing castings. All cast steel should be suitable for the intended application and will satisfy the

minimum requirements. Subject to these conditions, grades of cast steel conforming to the relevant

standards or the approved material specifications may be used. The grades of cast steel will

normally be identified by the standardized designations or the designations given in the

specifications.

Castings should be produced by approved methods and foundries wishing to supply castings must

be approved. These depends on their fulfilling the manufacturing and quality control requirementsand furnishing proof of this before starting. The scope of the necessary approval test will be

determined by Classification office.


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Heat Treatment

All castings must undergo heat treatment appropriate to the material performed in suitable

furnaces. The furnace dimensions must enable the entire casting to be raised uniformly to the

required temperature. Where this is not possible, other arrangements must be agreed. Where,

following final heat treatment, a casting is heated locally or undergoes hot or cold straightening, or

alignment, subsequent stress relief heat treatment may be required to remove residual stresses.

Flame cutting, flame scaring or flame gouging to remove excess material or feeders must be

carried out by a recognized method prior to final heat treatment. Pre-heating should always be

applied if the chemical composition or the thickness of the casting makes this necessary. Where

required, the heat-affected zones of the casting will be machined or ground off.

All castings must have a clean surface compatible with the conditions of manufacture. Minor

casting defects may be trimmed off within the negative tolerances on the wall thickness. The

dimensions and tolerances are governed by the values specified in the approved drawings or in the

relevant standards, as applicable. Castings subjected to internal pressure by an operating medium

or for which special proof of impermeability is required, must be resistant to leaks at the specified

test pressures after being machined.

The chemical composition must conform to the rules or the relevant standards and themanufacturer must ensure that the residual elements remain within the permitted limits.

Inspection

The manufacturer must inspect all castings for surface finish and compliance with the dimensional

and geometrical tolerances before presenting them for final inspection. Inside surfaces should also

be included in the inspection. The surface of the castings must be free from material from the

mould and must be properly prepared for inspection. This may involve pickling, local grinding,

shot or sand blasting, cleaning with brushes or chemical means. Chipping and hammering are

allowed only if this does not conceal surface defects.

If there is reasonable suspicion that unapproved welds have been carried out on a casting, you may

require certain areas of the surface to be etched in order to reveal them.

The manufacturer and/or finishing plant should perform NDT where required, using suitable

equipment, test facilities, and qualified test personnel. The test results must be certified and give

technical details of the test. The manufacturers monitoring system must enable all castings to be

traced back to the original heat, and this should be demonstrated on request.


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Fabrication Welding

Companies wishing to carry out fabrication welds on casting must have available the necessary

workshops, lifting gear, welding appliances, pre-heating and heat treatment facilities , testing

instruments and equipment as well as qualified welders and competent welding supervisions so

that the work can be properly executed. Compliance with these conditions must be proved and a

description of the welding facilities and procedures must be submitted.

Additional requirements apply to:

Castings of unalloyed and alloyed grades of cast steel intended for the manufacture ofcomponents and structural parts e.g. diesel engine components, gears, couplings, and also

stem and stern posts, stern tubes, shaft struts, rudder bearings and anchors.

Steel castings for crankshafts and connecting rods and throws and webs of builtcrankshafts and connecting rods made of carbon, carbon-manganese and low alloy grades

of cast steel.

Steel castings for use at low temperatures for cargo and processing equipment on gascarries at design temperatures below 0C, e.g. flanges, valve parts, weld-on and socket

welding pieces.

Steel castings made from austenitic and austenitic-ferritic grades of steel intended for usein cargo and processing equipment for chemical tankers and other equipment for whichchemical stability in relation to the cargo or operating fluid is required. These may also

apply to sleeves for propeller shafts and rudderstocks.


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1.5. Cast Iron

This item provides general information on the manufacture and testing of nodular and grey castiron. All castings must be suitable for their intended purpose and satisfy the specified minimum

requirements. The grades of cast iron will be identified by standardized designations or those in

the specifications.

Castings should be produced by approved methods and foundries wishing to supply castings must

be approved. This depends on their fulfilling the manufacturing and quality control requirements

and furnishing proof of this before starting. The scope of the necessary approval test will be

determined on a case-by-case basis.

All castings must have a clean surface and minor casting defects may be trimmed of within the

negative tolerance on the wall thickness. Castings must generally be free from defects liable to

impair machining operations and their subsequent use.

Feeders and excess material should be removed but where the method causes a structural change,

e.g. flame cutting, the cut faces must be machine afterwards. Fabrication welds, particularly

intended to improve the appearance of the casting, are not generally permitted except where a

prior test confirm the suitability of the process.


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Local porous areas not subject to internal pressure may be sealed with suitable materials. The

dimensions and tolerances are governed by the values specified in the approved drawings or in the

relevant standards, as applicable. Castings subjected to internal pressure by an operating medium

or for which special proof of impermeability is required, must be tightness tested at the specified

test pressure.

The manufacturer must determine the composition of each batch or ladle and confirm that the

required characteristics are achieved, providing a certificate if required. Impact energy and tensile

test should be carried out as necessary.

The mould material use for separately cast samples must be the same as that used for the casting

itself. The samples may not be removed from the moulds until their temperature has dropped to

below 500C. For chill mould casting, centrifugal casting and continuous casting, sample selection

will be by special agreement.

Sample markings must relate clearly to the castings they represent. If castings are heat-treated, the

samples must be heat treated with them. If castings are manufactured in series, the manufacturer

may us other, equivalent methods of testing.

InspectionThe manufacturer must inspect all castings for surface finish and compliance with the dimensional

and geometrical tolerances before presenting them for final inspection. Inside surfaces should also

be included in the inspection. The surface of the castings must be free from material from the

mould and must be properly prepared for inspection. Chipping and hammering are allowed only if

this does not conceal surface defects.


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1.6. Aluminum Alloys

Aluminum alloys are used where their properties of low density and high strength to weight ratio,

corrosion resistance in certain environments, or retention of toughness at low temperatures, are of

value. They are frequently used in the superstructures of large ships and for the entire hull

structure of some ferries and small boats, as well as surface effect and hydrofoil craft. Under

normal conditions, aluminum alloys do not generally experience excessive corrosion. But in

contact with dissimilar metals, they may corrode at an accelerated rate. In certain stagnant water

applications, such as bilge spaces or chain lockers, exfoliation corrosion may be concern. Then use

of alloys especially heat treated to resist such corrosion will be considered.

The general information in this item applies to wrought aluminum alloys with a product thickness

of 3 to 50 mm inclusive, intended for the fabrication of ships hulls, superstructures and other ship

structures as well as for pipelines. Products having thicknesses outside this range are to be

specially agreed with your office. We will not consider wrought aluminum alloys intended for the

manufacture of system designed to transport liquefied gases at low temperatures.

Alloy designations and material conditions indicated in the Rules will normally comply with the

designations of the Aluminum Association. Conformance to national standards or other

specifications may be acceptable provided the properties, suitability for use, and weldability have

been checked and approved.

For manufactures to be approved for the alloys and product forms in question, satisfactory

manufacturing and quality control requirements must be proven before production starts.

Plates may be hot rolled according to the characteristics required, i.e. strength, dimensions,

tolerances, etc. Section will be extruded. Pipes and bars will also be extruded followed by

drawing, if necessary. Pipes may also be fabricated from longitudinally welded strips. All products

will be delivered in the material conditions specified for the alloy concerned.


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Inspection

The products must have a smooth surface and be free of defects liable to impair further

manufacturing processes or the proposed application, e.g. cracks, laps, appreciable inclusions of

extraneous substances and major mechanical damage. Surface defects may be repaired only by

grinding provided these results in a gentle transition to the adjacent surface of the product and the

dimensions remain within the limits. Repair by welding is not permitted. Repairs must only use

tools exclusively applied for aluminum processing.

Note that unless otherwise agreed, the specific requirements in the Rules apply in respect of

permitted thickness tolerances:

For plates and strips or flats

For open sections

For close sections

Other product shapes and other dimensional and geometrical tolerances are subject to the

applicable standards.

The manufacturer must ensure compliance with specified tolerances and the general characteristics

required. Where NDT is necessary, the method and evaluation criteria must be agreed with

Classification office.

The manufacturer must determine the chemical composition and this must correspond to the data

given in the standards and the Rules. Slight variations from the specified composition may be

permitted by agreement, provided this does not impair the product performance. You may ask for

occasional check analyses but the analysis certificate produced by the manufacturer is normally

accepted.

Where the alloys are not cast in the same works in which they are made into semi-finished

products, you should be given a certificate issued by the smelting plant which indicates charge

numbers and chemical composition. The manufacturer of the ingots or extrusion billets must be

approved.

Casting alloys

These may be used for the fabrication of ships hulls an also for machine construction parts and

other shipbuilding components. Foundries must be approved for the grades of castings concerned.

If castings have to be weldable, this is to be stated in the order and proof of suitability.

Suitable grades of castings to international or national standards will generally be used, e.g. to

DIN 1725. Part 2. If castings conforming to manufacturers specifications are to be used, these

must be submitted for examination and approval.

Castings such as fittings, housings and fan rotors, which are exposed to the action of seawater ar

salty atmosphere without protection, should be made of suitable alloys.

Al-Si, Al-Si-Mg and Al-Mg alloys with a maximum copper content of 0.1% will normally be

used. Al-Si and Al-Si-Mg alloys not come into direct contact with seawater. Where necessary,

they are to be protected by anodes or coatings.

The manufacturer must confirm that the chemical composition of the castings matches the

standards or manufacturers specifications. The mechanical properties specified must also be met.


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All castings must be free from internal and external defects, which could adversely effect the

application, or any further manufacturing processes. If defects are to be repaired by welding, the

manufacturer should produce a welding specification for approval. Where stated in the order, or if

there is concern as to possible defects, the manufacturer should undertake NDT as appropriate.

For castings, which will form part of the ships hull or are designed as structural components of

the propulsion system, you should witness a tensile test to establish their mechanical properties.


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1.7. Copper Alloys, including Brass and Bronze

This item covers pipes and fittings made of copper and wrought copper alloys and intended for use

in pressurized lines and for condensers and heat exchangers. In the case of finned pipes, thespecifications should be submitted for approval.

Generally, the pipes will be manufactured by seamless methods, e.g. by hot pressing followed by

rolling and cold drawing. Where welded pipes or fittings are to be used, the characteristics of these

and the method of manufacture should be notified. You may always ask for a procedure approval

test in these cases. Cold-formed pipes and fittings will be subjected to recrystallization annealing.

Despite this, copper pipes, which are to be supplied in the half hard to hard condition may be

cold formed after annealing.

All pipes must be suitable for the intended application and satisfy the requirements specified in the

standards and rules. The permitted grades are shown in the standards and rules as indicated in the

example.

Copper and wrought copper alloy pipes for condensers and heat exchangers, e.g. according to DIN

1785, are preferable in the grades of pipe shown. Pipes conforming to other standards or

specifications may also be used, provided that they are comparable to the grades specified in the

rules and their suitability has been confirmed.


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Inspection

The pipes must have a smooth surface and be free from impurities, e.g. pickling residue or burnt

drawing lubricants. They should not be cracked or have suffered mechanical damage. Die marks

and laminations, which may impair further manufacturing operations or the use of the material are

not allowed. Surface defects may be repaired by grinding provided these results in a gradual

transition to the surface of the pipe and the dimensional tolerances are not exceeded. Repairs by

welding or soldering are not permitted. The tolerances on wall thickness and diameter will be

those prescribed in recognized standards.

Pipes must be straight to the eye except when supplied in coils. Pipe ends must be cut off at right

angles to the pipe axis and must be free from burrs. Pipes must not leak when submitted to the

hydraulic pressure test at the prescribed test pressures.

The manufacturer should provide you with the chemical composition of each manufacturing batch

and confirm that this as well as the mechanical properties conforms to the relevant standards. With

some specific exceptions, all pipes must be capable of being cold formed with the degrees of

deformation customary in workshop practice, e.g. by bending and expansion. Pipes made of

copper zinc alloys must be free from stresses liable to cause stress cracks. Copper pipes must not

become brittle due to the effect of hydrogenous gases and elevated temperatures such as occur, forexample, in gas welding, soldering and hot forming. In general, the average grain diameter of the

materials specified in the conditions mentioned in the rules should be between 0.01 and 0.05 mm.

The manufacturer should inspect the finish of the inner and outer surfaces of every pipe and check

the diameters and wall thickness. Then the pipes will be submitted to you for final inspection.

Fittings

The requirements for copper and wrought copper alloy fittings apply to branch saddles, T-shaped

fitting, tapered transition pieces and pipe elbows. Only fitting conforming to recognized standards

are to be used. Fitting manufacturers should prove the initial suitability of their products by means

of an approval test. The scope of testing is determined by the relevant standards.

The chemical composition and mechanical properties of the fittings must correspond to those of

the grades of pipe used for their manufacture. If testing is required then the procedure a required

then the procedure as required in the rules should be applied.

Castings

The rules also apply to cast copper alloys for the manufacture of valve and pump housings, shaft

liners, bushes and similar parts. The chosen method of manufacture should suit the shape of the

casting. Sand casting, chill casting, centrifugal casting and continuous casting may be used.

Castings may be supplied in the as cast or heat-treated condition at the manufacturers option

unless this is specified in the order.

The grades of cast copper alloys must be suitable for the intended application, e.g. conforming toDIN 1705, DIN 1706 and DIN 17658. Other standards or specifications may be used provided

their suitability has been confirmed.


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1.8. Notes on materialsGeneral requirements for materialsThe requirements for materials used in repairs are in general the same as the requirements for

materials specified in the Rules for new constructions.

Replacement material is, in general, to be of the same grade as the original approved material.

Alternatively, material grades complying with recognized national or international standards

may be accepted by the Class provided such standards give equivalence to the requirements of

the original grade or are agreed by the Class. For assessment of equivalency between steel

grades, the general requirements and guidelines in the Rules on materials apply.

Higher tensile steel is not to be replaced by steel of a lesser strength unless specially

approved by the Class.

Normal and higher strength hull structural steels are to be manufactured at works approved by

the Class for the type and grade being supplied.

Materials used in repairs are to be certified by the Class applying the procedures andrequirements in the rules for new constructions. In special cases, and normally limited to

small quantities, materials may be accepted on the basis of alternative procedures for

verification of the materials properties. Such procedures are subject to agreement by the

Society in each separate case.

Equivalency of material gradesAssessment of equivalency between material grades should at least include the following

aspects:

- Chemical composition,

- Mechanical properties,

- Heat treatment/delivery condition,

- Tolerances.

When assessing the equivalence between grades of normal or higher strength hull structural

steels up to and including grade E40 in thickness limited to 50 mm, the general requirements

in the table below apply.


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Requirements Comments

Chemical

composition

- C; equal or lower

- P and S; equal or lower

- Mn approximately the same but not

exceeding 1.6%

- Fine grain elements; in same

amount- Deoxidation practice

The sum of the elements, e.g. Cu, Ni, Cr

and Mo should not exceed 0.8%

Mechanical

properties

- Tensile strength; equal or higher

- Yield strength; equal or higher

- Elongation; equal or higher

- Impact energy; equal or higher at

same or lower temperature, where

applicable

Actual yield strength should not exceed

Rule minimum requirements by more

than 80 N/mm 2

Condition of

supply

Same or better Heat treatment in increasing order :

- As rolled (AR)

- Controlled rolled (CR)

- Normalized (N)

- Thermo-mechanically rolled 1)- Quenched and tempered (QT)1)

1) TM - and QT-steels are not suitable

for hot forming

Tolerances Same or stricter Permissible under thickness tolerances:

- Plates: 0.3 mm

- Sections: according to recognized

standards

Table giving minimum extent and requirements to assessment of equivalency between

normal or higher strength hull structural steel grades

2a. ISI-A. PEMELIHARAAN DAN PERBAIKAN KAPAL-1-30

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Transcript of 2a. ISI-A. PEMELIHARAAN DAN PERBAIKAN KAPAL-1-30