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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .411 c, Q8 ]: T, ]1 P1 k6 s
29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152
$ c9 g9 f) d; m2 L$ J( Y5 dmm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the
- x3 M6 q, x' N% U$ t- PNational Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate+ d d! t# y3 w0 Q4 v$ R9 S
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,
5 G5 ^7 A' L9 p! q& m. W0 ?0 ]/ t9 Q²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3., f; e" G5 S8 K6 |3 z3 w! V
29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of, e' i N2 }: R: d
the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.' p5 c# Q/ w' ^' ~1 N
29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor" ~9 m( z( B E% n7 E" t
pressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall
7 c; n3 q7 L2 P# v, t" |withstand without bursting or leaking a pressure equal to the highest of the following that is applicable:1 R6 w+ X# M) W' p2 Y5 ~
a) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve: i7 G& S! |' }
provided as part of the assembly, but no more than five times the marked maximum supply
; p& N( s2 h7 P) R/ d8 ?2 npressure from an external source and no more than five times the pressure setting of a5 q6 D1 c: A# F2 c* L" w
pressure-relief device provided as part of the assembly.
+ i. y6 j( n3 g0 ]/ E8 o ^b) Five times the marked maximum supply pressure from an external source, except as
: q- p1 {4 x' Aprovided in (a).
: W' k( X' o; _' Y3 \; `c) Five times the pressure setting of a pressure-relief device provided as part of the assembly.* e5 c0 O n3 A$ J7 l
d) Five times the maximum pressure that can be developed by an air compressor that is part of& H/ g" l9 P7 g% H ~
the assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
Q7 e$ s% z# z' Q5 N) U7 R! X; oe) Five times the working pressure marked on the part.% P' b7 i: a& F7 a! b6 i+ }
29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if# H# v, J$ J& }1 B) u$ E
study and analysis indicate that the strength of the part is adequate for the purpose as a result of its* f2 {6 l, _4 r9 Q8 _; W
material and dimensions – for example, copper or steel pipe of standard size and provided with standard
9 u( d4 L2 ?- Q; `+ Ifittings might be considered to have adequate strength.
$ A# Z8 ^. C# C2 C: [29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered
4 I1 O7 o0 g; B! P5 t7 Rto comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less
- O1 e( E/ i% K9 g5 ]than that to which it is subject during normal or abnormal operation.
0 z9 }. q# v; K+ [5 r; J% E+ W29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples. ]; @6 P3 p- p, w5 l+ U# }* A
of the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to2 c9 j. C+ F: k& i$ H
exclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the
# u4 X9 S; _) l. tspecified test value and is to be held at that value for 1 minute. The results are not acceptable if either) J# `! n1 c; s
sample bursts or leaks, except as indicated in 29.7.; J5 c8 c: Z2 y4 {1 A
29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a
" _' o; U7 ^: I' @pressure 40 percent or less of the required test value.: B+ I3 s6 ^" p
29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated
7 f! i6 G- g5 ^; Rin the event of fire.9 v0 V1 O8 o7 `& \
29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other
. \0 k8 H, m0 K# _# Qpressure-relief means or the equivalent may be employed to comply with the requirements in 29.8.
$ C! u6 ^. n4 @# v; Q U. Y2 Q29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended4 v' S& _6 R- h/ O- k5 t) m. y% X
to protect./ [) Z6 X4 K) O" g5 T
29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam
7 `( w5 r( r$ c) T+ l F; ?pressure generated or stored within the appliance shall be protected by a pressure-relief device.
% B$ Q. V/ F: \& S% C9 M+ @8 z29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the
2 ?+ M8 w2 Q$ ?& b0 H$ ?working pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the4 h5 Q) P5 P; Z& N, N/ Q! a
pressure.
; \$ p) I$ F5 f6 a29.13 A pressure-relief device shall comply with all four of the following:0 X) C" A1 @" u! z& V8 h: M' {
a) Shall be connected as close as possible to the pressure vessel or parts of the system that it
. R9 {, N, c% Z2 y) L0 `; sis intended to protect;0 T9 k/ t5 M W9 ^9 h8 q4 `& \
b) Shall be installed so that it is readily accessible for inspection and repair and cannot be/ i: y* x4 p3 C. A. D" g+ W! j$ `8 x
readily rendered inoperative;2 u% \. h! w+ U. c; D
c) Shall have its discharge opening located and directed so that the risk of scalding is reduced
( Z1 e" ~, n0 k) ito a minimum; and
4 ?1 W! K: g7 Pd) Shall have its discharge opening located and directed so that operation of the device does
g- ~! o6 v: O4 ]not deposit moisture on bare live parts or on insulation or components affected detrimentally by
) j# J, x" o Bmoisture." `: Z5 i! L0 B0 s
29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum
. q( h) \: }7 r; _' D4 H' u1 ^setting unless the adjusting means is sealed at a lower setting.
7 g ~! N% a# D4 G" |1 E1 _. b29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended$ E7 \: ], K+ u
to relieve excessive pressures automatically.1 r2 _* l: d% |9 D
29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the
6 k$ q% ~; p) H9 w+ Y8 z' K! uvessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent. C# G. C: r. s/ g
the pressure from exceeding 90 percent of the relief device setting under any condition of normal/ R& m5 M9 e% N
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