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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
. F- h7 d0 B+ @3 u+ R- O29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152. y4 \+ Q- H9 V2 w ?* d C# u+ D
mm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the% v0 ]3 ]1 z$ E& Q$ d# i. J" Y
National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate9 [" Z3 Y1 ?* j
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,1 g5 O$ P8 ~ ]# l6 E* e K
²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.
]% ^: n( p5 m" f5 w/ m29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of
4 g/ z y2 z% nthe ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.5 {$ g( U4 e+ U z& I( t' Z
29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor, R/ u5 b J# h
pressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall* |2 C# W% c% p ~6 P! E- h5 ]
withstand without bursting or leaking a pressure equal to the highest of the following that is applicable:
3 [ C5 W1 |/ c( ja) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve( m7 o) {8 r7 [% D" X/ |! A
provided as part of the assembly, but no more than five times the marked maximum supply
1 x2 l9 e( i) e1 }7 r5 j; jpressure from an external source and no more than five times the pressure setting of a( h4 M3 s! \, j- S
pressure-relief device provided as part of the assembly.1 N" Z! J" H1 Y( X
b) Five times the marked maximum supply pressure from an external source, except as( H& H- u. }# Z3 R$ n3 X4 S# s1 h, q
provided in (a).
* A" q/ `2 s1 S9 J1 cc) Five times the pressure setting of a pressure-relief device provided as part of the assembly.' m1 U. C4 ?& Q7 W+ _7 u# `
d) Five times the maximum pressure that can be developed by an air compressor that is part of
# F2 o; }/ z. l' k/ q6 Cthe assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).1 l) V a0 o1 B& G8 _$ E
e) Five times the working pressure marked on the part.% t" g7 a5 X! F; N5 X6 l
29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if( f( m0 b* ~0 Y7 X
study and analysis indicate that the strength of the part is adequate for the purpose as a result of its( @4 K& S! |9 |7 z
material and dimensions – for example, copper or steel pipe of standard size and provided with standard
/ v' m+ J" H$ h5 j5 \3 efittings might be considered to have adequate strength.: Q$ Q1 B3 f0 P6 O+ z* W! K
29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered' M4 U1 n$ D0 H6 V" v6 X3 U- [4 V
to comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less2 b2 w2 ?9 k4 ]7 A6 R% J
than that to which it is subject during normal or abnormal operation.
/ ]0 R) a) U- ^% Q' }8 v29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples
D/ u4 r# H( _8 x2 V% s" Zof the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to& S% H# V2 z% U- ^. p: S% k; O
exclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the
4 F- A e% |7 Q! o0 w# _specified test value and is to be held at that value for 1 minute. The results are not acceptable if either
+ w3 W3 a4 [+ H; \/ Zsample bursts or leaks, except as indicated in 29.7.$ F, ~ N/ S- G5 h& [
29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a9 s/ ?+ V- `# G: i3 h
pressure 40 percent or less of the required test value.0 [4 }! T$ ~6 j% W# v/ Q1 W8 f' b1 q+ V
29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated% {3 F" Z3 l% W1 K. ]$ d6 ]- J
in the event of fire.
5 I: ^! B: x. `* a! k29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other
' ?- h7 u1 Q1 t$ b( D: z: p# apressure-relief means or the equivalent may be employed to comply with the requirements in 29.8.
# x- Q$ i# T6 W2 g29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended
2 c( u+ v. n3 C; _+ Sto protect.
F, r ]+ G2 J8 y29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam' @/ i0 R& ?- }# ]; u$ |; V2 u0 d* G
pressure generated or stored within the appliance shall be protected by a pressure-relief device.5 s9 W6 p! l9 X1 e5 `
29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the
# l5 v% h( X! D5 t- bworking pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the
' b+ R) n# I6 T/ P( E: x kpressure.5 F5 A5 \( Y2 c( o' U
29.13 A pressure-relief device shall comply with all four of the following:! b: t/ K$ f! ?# I8 I [
a) Shall be connected as close as possible to the pressure vessel or parts of the system that it
- s/ i8 g) V0 d3 _is intended to protect;
+ i" S* h2 I* m2 J$ N, M$ ]/ yb) Shall be installed so that it is readily accessible for inspection and repair and cannot be1 X5 a+ [4 d( e2 `
readily rendered inoperative;
1 H6 \3 ?0 J$ t* pc) Shall have its discharge opening located and directed so that the risk of scalding is reduced( Z, S6 m! y, q% T8 H2 f
to a minimum; and$ V9 s/ K0 N2 y4 q0 S
d) Shall have its discharge opening located and directed so that operation of the device does l$ m( a$ D: R# E c2 ]
not deposit moisture on bare live parts or on insulation or components affected detrimentally by; H7 n5 s: E( u5 I* r( Z
moisture.
2 q( R) ]( y( `5 f. F+ Y" f29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum$ \9 @. ]% e) Q
setting unless the adjusting means is sealed at a lower setting.7 q) Z! ]* m! ^, V4 N$ z' }
29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended* Z- n* g" a+ D
to relieve excessive pressures automatically.
3 H7 A4 ~; ?; G% W1 R1 `* o29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the
; w- \! Z* W3 a) o' f+ g3 tvessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent
& u& f6 h, c2 b* Y* ?, N3 P9 `the pressure from exceeding 90 percent of the relief device setting under any condition of normal, P3 \1 U' k7 q
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