|
29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
8 ^: t9 i' j. P& U6 @, g' a29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (1528 s& K5 J- {% x2 o- W4 a
mm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the. l3 r! o2 Z& k
National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate \4 G2 |2 Q' @
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,' Y9 R1 _4 `. \$ U3 ]2 b
²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.
: K" [: a" N5 m" x P29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of% F3 t- n9 ]. o3 [7 @
the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.
; U& W* z6 ^ `0 D29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor
/ f# R% a; y% }7 R+ H, [pressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall5 I# w# k5 B+ c* p4 W0 l9 l
withstand without bursting or leaking a pressure equal to the highest of the following that is applicable:
( H3 O' }" R. \ H( w3 a0 Qa) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve
7 ?/ p+ b. e+ X4 C( c5 xprovided as part of the assembly, but no more than five times the marked maximum supply4 q( S5 r" _2 I; q4 H- L
pressure from an external source and no more than five times the pressure setting of a* G( j' }) ]- l; u* T
pressure-relief device provided as part of the assembly.3 e U2 q* W/ c9 p. e; ?; g
b) Five times the marked maximum supply pressure from an external source, except as7 Q5 A j% A! n! s6 b( L
provided in (a).
$ }& q) N" p7 v# T, d+ k2 u0 U& s( gc) Five times the pressure setting of a pressure-relief device provided as part of the assembly.# B5 M9 ?5 Y- E# U# }% Z/ r5 _
d) Five times the maximum pressure that can be developed by an air compressor that is part of+ T; L2 G1 N, s. C
the assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
' o' a% }7 [" `( B9 ?! q& k* X& |e) Five times the working pressure marked on the part.
* Q1 J+ R/ F9 w+ f# |29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if
) [- X% H! U% Y4 W8 B8 estudy and analysis indicate that the strength of the part is adequate for the purpose as a result of its
% H' [+ @4 S* o6 wmaterial and dimensions – for example, copper or steel pipe of standard size and provided with standard
: g- d0 |1 s4 H$ ]! }7 \2 jfittings might be considered to have adequate strength.
- Y M2 q/ T3 W' E; k29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered) U& I2 Q$ T+ v
to comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less K9 K8 t% d# [
than that to which it is subject during normal or abnormal operation.
4 Q/ G" {/ C9 t1 ^6 _; k, S7 j. o% \29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples1 H0 Z6 z- {8 V! s
of the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to
) H* v, h6 K, }) Q0 Zexclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the6 ~* W9 x# O3 J# e7 B& I9 u& t: N+ n( \
specified test value and is to be held at that value for 1 minute. The results are not acceptable if either
* Z, F8 d( b- j; d, w6 xsample bursts or leaks, except as indicated in 29.7.5 g% I+ j5 o. N0 c Y( j$ l
29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a1 R# j. D- u0 H3 D7 w
pressure 40 percent or less of the required test value.
/ o# J% B4 ^8 o% q- n4 f U7 {29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated& \* W8 B8 E' O7 F& a
in the event of fire.( R7 }0 ?. S5 M- @
29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other
! d9 B' N. P' [3 }+ u1 rpressure-relief means or the equivalent may be employed to comply with the requirements in 29.8.; u& N, H3 ]0 L
29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended, ~$ J9 e. q& V( O& `
to protect.
& f" F1 w' E9 _9 y1 y29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam \9 @* l% ~5 T6 x
pressure generated or stored within the appliance shall be protected by a pressure-relief device. p) {/ Q2 s, C! i
29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the" s5 ]/ ^6 B) W4 A" ]" |) c% e
working pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the
3 {- B0 m5 I( w0 j# ~' @pressure.. a$ o$ L6 D9 Y- c
29.13 A pressure-relief device shall comply with all four of the following:/ F d) {0 @& i. i! p+ M3 [
a) Shall be connected as close as possible to the pressure vessel or parts of the system that it- `( A9 I: T9 n$ Q) w
is intended to protect;% \* g- E# a+ i# }
b) Shall be installed so that it is readily accessible for inspection and repair and cannot be6 F) ?, P s3 E8 ^. W
readily rendered inoperative;) B/ t) e; X" a2 Q3 N% v
c) Shall have its discharge opening located and directed so that the risk of scalding is reduced5 p0 W6 j* ?. Y' _5 X2 J! D
to a minimum; and2 m& v [; H0 m# ~$ ~0 |/ I
d) Shall have its discharge opening located and directed so that operation of the device does$ S" x& j# ]) P1 e7 j I
not deposit moisture on bare live parts or on insulation or components affected detrimentally by
- i G9 g% T7 ?6 ]moisture.
! Z/ A. B9 J0 D! Y, L29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum
0 b! v) m/ L3 e. q Psetting unless the adjusting means is sealed at a lower setting.
0 q" v+ P* `; K* C( k29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended
+ ^8 h& [' R: u4 O/ `1 b. S, O) w$ \to relieve excessive pressures automatically.
: X4 c3 [, \0 n7 A4 u, G7 M W; t29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the* D/ y. n/ C8 i/ |0 p
vessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent
- Q# T! ^0 H! D" X3 j6 Qthe pressure from exceeding 90 percent of the relief device setting under any condition of normal) ~" u- c; N& D0 q
operation. |
|