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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .419 P J# K1 k2 P+ a) _7 S, X: s
29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152
1 Y% _9 I2 R/ l8 ~+ ~9 T; vmm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the* D6 H' a; Y2 `
National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate
; r. r- l. H9 c& o) d `boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,: G% o1 |- O# {6 B
²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.
6 n, K8 ?: P/ l- U; l) w29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of: F! ~8 _* {8 h& n5 H& ?
the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.
; u5 T9 f0 Y# }; B- g29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor
2 }# Q/ F+ h! W: vpressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall
: z4 i- W- Z% Z5 u( f$ [0 w; Awithstand without bursting or leaking a pressure equal to the highest of the following that is applicable:2 G# I4 g. }- v7 E2 m! h7 ^/ \
a) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve$ P4 K9 Q% s! e* T9 f
provided as part of the assembly, but no more than five times the marked maximum supply7 j5 j# |! E2 ]; k2 b. L
pressure from an external source and no more than five times the pressure setting of a
; K) w0 ^- E) f7 N) U6 ~- k. _pressure-relief device provided as part of the assembly.
: A! j4 h: t2 r a. d: wb) Five times the marked maximum supply pressure from an external source, except as
' ~5 k3 w5 F+ [, Kprovided in (a). a: |+ I' M6 Z: I
c) Five times the pressure setting of a pressure-relief device provided as part of the assembly.: C: x X# W1 ~- R
d) Five times the maximum pressure that can be developed by an air compressor that is part of
( {! K' b! X4 i1 U5 mthe assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
( b8 i" P5 q8 z! N ^8 _e) Five times the working pressure marked on the part.
3 k! _- d# O3 L9 I+ [ w0 i29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if$ r3 h! q* v i. p) L% I
study and analysis indicate that the strength of the part is adequate for the purpose as a result of its1 K k' F9 A/ u4 o
material and dimensions – for example, copper or steel pipe of standard size and provided with standard
6 h2 c. I/ Q$ efittings might be considered to have adequate strength.
- [+ I, B7 w% z# z: _; u' T* {9 P3 ^29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered0 J8 }, |& M% Z' |4 K1 w4 U0 {5 d
to comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less
0 b- `( o/ f5 Y2 Gthan that to which it is subject during normal or abnormal operation.1 A, G" L m+ ]' {# T
29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples% I0 R& R8 g/ H( ^# v3 P ?7 E% Y
of the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to8 Q3 i4 A' u9 `) t- a$ @# v( V( y
exclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the+ L& J3 W8 b1 A! H2 a$ y( J5 L
specified test value and is to be held at that value for 1 minute. The results are not acceptable if either% R$ }( w' [* l% ^) B! Z
sample bursts or leaks, except as indicated in 29.7.
1 v7 E2 Z# ~3 H! i29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a- O$ I( ^/ i7 v, v6 g& p8 \2 t8 j
pressure 40 percent or less of the required test value." v9 _; ~8 ^" T5 N% ?! C1 U( {- @& F
29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated, K9 C+ Z7 X* h. r
in the event of fire.
7 n( }. Y, ~% Y29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other9 o% n) r0 h. b4 J) q
pressure-relief means or the equivalent may be employed to comply with the requirements in 29.8.. g6 c6 i/ h, D
29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended
. |; V! \# B/ oto protect.5 o) _$ @7 R# \, j3 W
29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam# q3 y+ o# t% j0 o( i
pressure generated or stored within the appliance shall be protected by a pressure-relief device.0 B/ o" l' Q4 x
29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the) J, A2 @( r+ U* N
working pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the
9 B- M4 E7 p( n- P/ X: X/ Fpressure.
3 p; u+ G( X; `0 S& V29.13 A pressure-relief device shall comply with all four of the following:! ~7 b# Y# n, e* D8 j9 \. _
a) Shall be connected as close as possible to the pressure vessel or parts of the system that it0 r+ ~; T) E3 ?5 S, ]* f. H2 p
is intended to protect;
7 I+ M& z. w4 |0 g5 zb) Shall be installed so that it is readily accessible for inspection and repair and cannot be
) \- |) a! y+ lreadily rendered inoperative;
* ~2 _( l% H f$ D2 Nc) Shall have its discharge opening located and directed so that the risk of scalding is reduced
4 l7 ~4 V4 p- U+ [to a minimum; and
B0 _; @4 n |d) Shall have its discharge opening located and directed so that operation of the device does6 _8 i2 ]) ]8 q$ S: o a3 Y
not deposit moisture on bare live parts or on insulation or components affected detrimentally by7 w* s" |1 k$ H" Q
moisture.- K9 o2 u: i& `8 F1 ]
29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum6 Z! K1 a: z) C) K( @- W L
setting unless the adjusting means is sealed at a lower setting.
9 y" y: g! V# T# s29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended
/ r- w; p: T t/ U; p' Cto relieve excessive pressures automatically.
5 h' h& b2 [( t. j. T29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the
1 \3 ~5 F* J2 @, i4 S; Lvessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent
& s; A9 A+ }. H, Rthe pressure from exceeding 90 percent of the relief device setting under any condition of normal
1 g0 T H/ \+ Q; {/ ]operation. |
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