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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
/ y/ T, ]/ j: v( c, r4 a3 I+ e9 |+ M29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152) w* r5 E: b; Z* o' r
mm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the
# z$ }/ z: v" d5 V$ \National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate& ~* a" r9 @/ j' T8 t& u9 X
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,
/ X- C9 @. {1 R4 h7 |' @²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.
& A* {2 u- x7 r+ I) s: E6 s* N29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of5 Y8 g+ _" m- A3 M* j
the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.
/ I/ Y3 b; T: _4 Y& E9 k" G29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor
! z" M/ {* z+ Kpressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall& ~* ^1 d, |$ @1 a9 A
withstand without bursting or leaking a pressure equal to the highest of the following that is applicable: ~; a2 M8 c0 S6 g4 K( p5 G
a) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve4 c! R2 H9 M9 p" R# r
provided as part of the assembly, but no more than five times the marked maximum supply/ R7 X. X5 w' r( H. Q3 w
pressure from an external source and no more than five times the pressure setting of a
& y' r# v3 k( k! l. `5 e$ \, X$ Upressure-relief device provided as part of the assembly.9 B o) `2 d& J2 z% W4 m
b) Five times the marked maximum supply pressure from an external source, except as
+ B! I2 P c4 Eprovided in (a).
1 `7 F. ^7 F4 O$ p+ Yc) Five times the pressure setting of a pressure-relief device provided as part of the assembly.5 G: c7 J {& f1 \! X
d) Five times the maximum pressure that can be developed by an air compressor that is part of4 Y0 ~& C1 P7 Y$ x
the assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
9 J9 h0 Q2 \) D! f9 V, @e) Five times the working pressure marked on the part.. D( Y$ X: J1 K6 A
29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if9 C/ }* ^2 ~6 `+ q4 q+ \, ?
study and analysis indicate that the strength of the part is adequate for the purpose as a result of its2 o1 V h+ g( G0 {0 Z5 k" W
material and dimensions – for example, copper or steel pipe of standard size and provided with standard5 K" t: a5 C& C: C
fittings might be considered to have adequate strength.
* N0 v- d9 t6 P2 z6 A( c29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered
: g- ]6 S7 @" i% |: Zto comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less& k" t# c4 L2 o+ t9 X! Q9 W
than that to which it is subject during normal or abnormal operation.& m" R1 v7 G. E8 n, Y, ~
29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples
6 Q ^# Y. T9 }of the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to; S. [9 T* g1 X
exclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the
K) |% ?; i5 T; } [7 R& }; Jspecified test value and is to be held at that value for 1 minute. The results are not acceptable if either
+ Y7 N- S" h9 B$ B# N2 P |sample bursts or leaks, except as indicated in 29.7.4 R% a$ n# G, m+ ?
29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a
* m% N9 w. K# }5 r5 E6 fpressure 40 percent or less of the required test value.4 ^' z* b% W8 L, K6 G
29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated
; W! K; h4 u8 [* Z ]9 hin the event of fire.( G7 G$ \6 F, |
29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other
8 [8 ^1 i2 D8 D; s; q0 T3 Z% E3 `pressure-relief means or the equivalent may be employed to comply with the requirements in 29.8.1 A- \: [% @9 w C
29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended
" a$ `1 G4 b2 x" Y% M: u& \9 vto protect.
) k: x* q* j- @% k+ V# q% F29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam
2 P1 M! y- B8 b% f+ J9 Upressure generated or stored within the appliance shall be protected by a pressure-relief device.3 }, Z; f* e1 z5 C u
29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the
4 N6 k V K$ C" {/ T6 iworking pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the
) p8 U; N/ `7 K) {) Opressure.
7 d7 ` T4 f8 u9 k29.13 A pressure-relief device shall comply with all four of the following:
6 y' p- p5 e& j9 b6 V1 ]! Ja) Shall be connected as close as possible to the pressure vessel or parts of the system that it3 q/ L3 u8 s+ x, V; ~6 G E5 i
is intended to protect;
/ Y- R! r6 f! X. kb) Shall be installed so that it is readily accessible for inspection and repair and cannot be
1 J# S) H3 y7 L E+ x! Z. Dreadily rendered inoperative;% a! G& J2 k: w8 b7 n; m
c) Shall have its discharge opening located and directed so that the risk of scalding is reduced. O* z1 [0 e5 E
to a minimum; and3 K ]3 L3 `0 ^& h& F! c- H6 H
d) Shall have its discharge opening located and directed so that operation of the device does
, C; r5 s7 _2 inot deposit moisture on bare live parts or on insulation or components affected detrimentally by" O; a3 A# T* Q
moisture.
7 i- ^6 F4 Z w$ @& ?29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum2 g$ w/ y, Y, m) F( @9 P
setting unless the adjusting means is sealed at a lower setting.
f8 Z" J3 ` @% _5 |: [: D29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended
1 z/ ~: k; B# Sto relieve excessive pressures automatically.
2 v% w& _- o/ V: Q: ~29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the
2 Y- d9 J$ K" i1 S2 ?vessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent
/ ?& G4 b! {4 V! ythe pressure from exceeding 90 percent of the relief device setting under any condition of normal
5 o C( Z" m8 S* foperation. |
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