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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
4 N5 I, s7 K0 l1 c( ?29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152 I; F5 O/ q7 _# G' m2 U
mm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the
6 C3 R+ k* [* B+ q# k& j) L5 `National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate T$ I8 n/ Q$ X# b% ~
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,& G; \" y+ ^ K1 k7 M
²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.8 J; f6 @& r8 n/ \6 b" I
29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of
! h& p& X' U C- ]the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.
* N% [/ _+ i7 K5 O. c6 t: J29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor
; e4 R0 v2 Z; Q. |% npressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall3 d9 V7 Z6 N$ |2 [
withstand without bursting or leaking a pressure equal to the highest of the following that is applicable:
' R! C4 C5 [" M2 ?4 m, e! w: e$ Na) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve' k6 Y, s% P# c9 Z3 J1 B' x( u
provided as part of the assembly, but no more than five times the marked maximum supply
, J! @: k0 D3 z1 w, u' rpressure from an external source and no more than five times the pressure setting of a
- d/ U( h# T9 Q# z W9 [& @pressure-relief device provided as part of the assembly.
; A5 o! w# e: X% I4 N% t. H' ab) Five times the marked maximum supply pressure from an external source, except as
% M/ P4 W$ K# s4 ?! {6 Zprovided in (a)." B* E* v& p& G
c) Five times the pressure setting of a pressure-relief device provided as part of the assembly.
8 i( u0 O& P( y: q3 zd) Five times the maximum pressure that can be developed by an air compressor that is part of
" p. e; Z2 w) i- ?9 tthe assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
* ~& K$ q, O; e; k, A6 ?6 be) Five times the working pressure marked on the part.
' ^( v/ x M7 J. }) g9 D) m- @5 E3 ^- {29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if: K3 A3 P+ a( W" [5 i
study and analysis indicate that the strength of the part is adequate for the purpose as a result of its' `) d( a, s |
material and dimensions – for example, copper or steel pipe of standard size and provided with standard
, Q* X+ h! t3 V+ s+ @+ Afittings might be considered to have adequate strength.% ]" h7 {+ {$ i/ L7 ?4 {3 d
29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered5 i( J7 a/ w6 y7 K7 K
to comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less O" `! }3 M. G: J! _
than that to which it is subject during normal or abnormal operation.6 N, k" c5 S9 O% M
29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples
1 C; n5 ?0 C' Nof the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to
0 K L7 r' x0 G& Kexclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the8 h& `! _0 z: f# ?+ U8 {) l
specified test value and is to be held at that value for 1 minute. The results are not acceptable if either. e* B$ d* v5 V
sample bursts or leaks, except as indicated in 29.7.
, x1 G- o) i$ _29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a4 f9 \' v6 n% I. l w6 t& s
pressure 40 percent or less of the required test value.
" r% U! q9 n& o29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated; @( t% H0 e2 x
in the event of fire./ J9 E( \5 F' E. E/ l5 t4 I- q( W
29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other- Y3 t0 K0 B1 s- q* `
pressure-relief means or the equivalent may be employed to comply with the requirements in 29.8./ ~! u2 Q" D* L$ S
29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended
$ Q |; N& s J6 S% t L+ C6 jto protect.
( y- U- L0 |4 m29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam4 i0 J, G' V( g0 c0 J9 w
pressure generated or stored within the appliance shall be protected by a pressure-relief device.
& y1 f7 S' R% H+ l/ W29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the
9 r6 e |5 Y) r+ qworking pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the
# T S0 b' ~/ U' ^$ ~* R( ~" a+ }$ \pressure.
* }4 t7 b0 N* v( z1 j1 R5 S29.13 A pressure-relief device shall comply with all four of the following:
# P) P. G+ q x2 x5 \$ la) Shall be connected as close as possible to the pressure vessel or parts of the system that it- b3 \) a6 \* b6 @: x- K2 H
is intended to protect;) J% C6 v4 P8 p5 U4 g1 ?: Q& u
b) Shall be installed so that it is readily accessible for inspection and repair and cannot be
. _6 p* X6 ?1 v( R0 u+ z; G, }readily rendered inoperative;8 ?4 y* G; D8 t# C" u- ]
c) Shall have its discharge opening located and directed so that the risk of scalding is reduced
% T( B5 L! n$ o) M' h1 T1 bto a minimum; and
/ E# s% v' b! |) m8 u& P/ n* n5 Dd) Shall have its discharge opening located and directed so that operation of the device does U7 g* Y7 ]1 I5 G* G. Y
not deposit moisture on bare live parts or on insulation or components affected detrimentally by
" P" Z- _$ h$ v1 n( O) A5 nmoisture.
& K% _5 ]( \# b) _$ O6 ~# L29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum
+ ^. a S) H' wsetting unless the adjusting means is sealed at a lower setting.1 S1 n% `6 F7 I
29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended z( L0 ^9 F' p$ h/ v' @0 h
to relieve excessive pressures automatically.- h0 l) r' G' L
29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the2 K/ I" @% ]; k: C) _5 w( V
vessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent& h0 q9 ?% l, |" b/ u% J( j/ L
the pressure from exceeding 90 percent of the relief device setting under any condition of normal) b# t) @! p. I0 ?
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