NOZZLE

Nozzle merupakan inlet atau masukan dan outlet atau keluaran suatu fluida pada suatu pressure vessel. Nozzle biasanya dipasang pada shell atau head yang nantinya sebagai tempat sambungan ( connection ) dengan pipa-pipa distribusi.

Gambar Nozzle

Simbol-simbol petunjuk yang ada pada nozzle sebagai referensi untuk menghitung nozzle terdapat pada UG-37 ASME seperti berikut ini :

Struktur Nozzle

Keterangan :

F = faktor koreksi yang mengganti kerugian untuk variasi pada desakan internal tekan yang berbeda . Satu nilai dari 1.00 harus dipergunakan bagi seluruh konfigurasi terkecuali itu UG - 37 mungkin dipergunakan untuk bukaan pada kulit silindris dan kerucut. [See UW-16(c)(1).]

Fr = Strength reduction factor. Tidak lebih besar dari 1. [See UG-41(a)] Fr1 = Sn / Sv untuk kedalaman dinding nozzle. Fr1 = 1.0 for nozzle abbuting the vessel wall. [See fig.UG-40(sketch j,k,n,o)] Fr2 = Sn /Sv Fr3 = lebih kecil dari Sn, Sv Fr4 = Sp / Sv h =distance nozzle projects beyond the inner surface of the vessel wall. (Extension of

the nozzle beyond the inside surface of the vessel wall is not limited; however, for reinforcement calculations, credit shall not be taken for material outside the limits of reinforcement established by UG-40.)

K1 = spherical radius factor (see definition of tr and Table UG-37) L = length of projection defining the thickened portion of integral reinforcement of a

nozzle neck beyond the outside surface of the vessel wall [see Fig. UG-40 sketch (e)] P = internal design pressure (see UG-21), psi (MPa) R = inside radius of the shell course under consideration R = inside radius of the nozzle under consideration

S = allowable stress value in tension (see UG-23), psi (MPa) Sn = allowable stress in nozzle, psi (MPa) (see S above) Sp = allowable stress in reinforcing element (plate), psi (MPa) (see S above) Sv = allowable stress in vessel, psi (MPa) (see S above) t = specified vessel wall thickness, 25(not including forming allowances). For pipe it

is the nominal thickness less manufacturing undertolerance allowed in the pipe specification.

te = thickness or height of reinforcing element (see Fig.UG-40) ti = nominal thickness of internal projection of nozzle wall tn = p nozzle wall thickness.25 Except for pipe, this is the wall thickness not

including forming allowances. For pipe, use the nominal thickness [see UG-16(d)]. tr = required thickness of a seamless shell based on the circumferential stress, or of a

formed head, computed by the rules of this Division for the designated pressure, using E p 1, except that:

(a) when the opening and its reinforcement are entirely within the spherical portion of a torispherical head, tr is the thickness required by 14(d), using M = 1;

(b) when the opening is in a cone, tr is the thickness required for a seamless cone of diameter D measured where the nozzle axis pierces the inside wall of the cone;

(c) when the opening and its reinforcement are in an ellipsoidal head and are located entirely within a circle the center of which coincides with the center of the head and the diameter of which is equal to 80% of the shell diameter, tr is the thickness required for a seamless sphere of radius K1D, where D is the shell diameter and K1 is given by Table UG-37.

trn = required thickness of a seamless nozzle wall. W = total load to be carried by attachment welds (see UG-41)

Berikut ini adalah data-data yang diketahui dari pressure vessel yang akan dirancang dan direncanakan :

Properti Vessel : Type Vessel : Horizontal Jenis Head : Hemispherical Jenis shell : Silindris

Material Vessel : Material Vessel & Head : SA 533 Gr.50 Tegangan Yield (sy) : 50000 Psi Modulus Elastisitas : 180952.381 Psi

Data Gas : Density (ᵨ) : 0.025 Lbm/in3

Kondisi Kerja : M.A.W.P : 400 PsigInternal Pressure : 217.5566 PsiTemperature : 400 0 FCorrosion Allowance : 0.1 inchEksternal Pressure : 14.69595 Psi

Dimensi Pressure Vessel yang Direncanakan : Diameter Shell : 15 Inch = 381.15 mm Panjang LOA : 40 Inch = 1016.4 mm Panjang Shell : 30 Inch = 762.3 mm Lebar Plat Saddle : 4 Inch = 101.64 mm

Data yang diperlukan untuk menghitung reinforcement Nozzzle : Diameter Shell = 15 Inch = 381.15 mm Inside Diameter Nozzle (d)= 50.8 mm Perhitungan tebal shell dari yang sebelumnya : tr : ketemu 4 mm.

Perhitungan tebal tn :

Inside Diameter nozzle = 50.8 mm = 2 inchRadius = 25.4 mm = 1 inch tn = P*R = 239.31226*7.5 = 0.00480003 inch = 0.121921 mm

S*E-0.6P ((50000*1)-(0.6*239.31226))

jika corrosion allowance = 2.541 mmmaka desain tebalnya = 0.91441+2.541 = 2.662920754 mmDigunakan material shell dengan tebal = 3 mm

t = 5 mm Sn = 16200 Psi Sv = 16200 Psi Fr = 1 Fr1 = 1 Fr2 = 1 Fr3 = 1 Fr4 = 1 E = 1 trn = 0.28 mm ti = 0.6 mm te = 0.75 mm h = 0.5 mm leg 41 = 0.56 mm leg 43 = 0.65 mm leg 42 = 0.688 mm Dp = 80 mm

Perhitungan Nozzle Jika Tanpa Reinforcement Pad :

A = 50.8*4*1+2*3*4*1(1-1) A = 203.2 mm2

A1 = A1 = 50.8(1*5-1*4) - 2*3(1*5-1*4)(1-1)A1 = 50.8 mm2

A1 = A1 = 2(5+3)(1*5-1*4) – 2*3(1*5 – 1*4)(1 – 1) A1 = 16 mm2

Nilai A1 diambil yang paling besar : 50.8 mm2

A2 = A2 = 5 ( 3 – 0.28) *1*5A2 = 68 mm2

A2 = A2 = 5 ( 3 – 0.28) *1*3A2 = 40.8 mm2

Nilai A2 diambil yang paling kecil : 40.8 mm2

A3 = A3 = 5*5*0.6*1A3 = 15 mm2

A3 = A3 = 5*0.6*0.6*1A3 = 1.8 mm2

A3 = A3 = 2*0.5*0.6*1A3 = 0.6 mm2

Nilai A3 diambil yang paling kecil : 0.6 mm2

A41 = A41 = (0.56)2 * 1A41 = 0.74833 mm2

A43 = A43 = (0.65)2 * 1A43 = 0.8062 mm2

Total Area Available :

A tot = A1 + A2 + A3 + A41 + A43 = 50.8+40.8+0.6+0.7483+0.8062 = 93.7545 mm2

Karena Atot < dari A maka butuh reinforcing pad. Berikut perhitungannya :

A1 sama = 50.8 mm2

A3 sama = 0.6 mm2

A2 = A2 = 5 ( 3 – 0.28) *1*5A2 = 68 mm2

A2 = A2 = 2 ( 3 – 0.28) (2.5*3 + 0.75)*1A2 = 44.88 mm2

Nilai A2 diambil yang paling kecil : 44.88 mm2

A41 = A41 = (0.56)2 * 1A41 = 0.74833 mm2

A42 = A42 = (0.688)2 * 1A42 = 0.829 mm2

A43 = A43 = (0.65)2 * 1A43 = 0.8062 mm2

A5 = A5 = (203.28 – 50.8 – 2*3)*0.75*1A5 = 51.15 mm2

Total Area Available :

A tot = A1 + A2 + A3 + A41 + A43 = 50.8+44.88+0.6+0.7483+0.829+0.8062+109.86 = 208.5235 mm2

Karena Atot > dari A maka tidak butuh reinforcing pad lagi.