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29 Pressure Vessels and Parts Subject to Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .416 r$ i) P4 S! A: r7 K: L
29.1 Except as noted in 29.2, a pressure vessel having an inside diameter of more than 6 inches (152 N) v+ {$ |9 g+ R1 H2 h; E2 F$ A
mm) and subject to a gauge pressure of more than 15 lbf/in2 (103 kN/cm2) shall be certified by the- `5 ^9 ~" }+ k1 ~$ E4 D
National Board of Boiler and Pressure-Vessel Inspectors and marked in accordance with the appropriate5 ?/ c- E+ c/ U" q' q
boiler and pressure vessel code symbol of the American Society of Mechanical Engineers (ASME) (²H²,
5 @7 T! S% [( I9 O²M², ²S², or ²U²) for a working pressure not less than the pressure determined by applying 29.3.; q: d( n$ \8 l: C6 O
29.2 If a pressure vessel, because of its application, is not covered under the inspection procedures of+ \% m" o' D2 k& S' X* L( t
the ASME code, it shall be designed and constructed so that it complies with the requirements in 29.3.
7 c' E* A" @7 U) }29.3 Except as noted in 29.4 and 29.5, a part that is subject to air or vapor pressure (including the vapor1 K8 W; y2 | I! f# m! c3 R
pressure in a vessel containing only a superheated fluid) during normal or abnormal operation shall# \. [- U9 n+ Q: w2 E5 t. h
withstand without bursting or leaking a pressure equal to the highest of the following that is applicable:" L a$ u3 Q) q
a) Five times the pressure corresponding to the maximum setting of a pressure-reducing valve
6 s! y/ a) O4 ]8 i: {( fprovided as part of the assembly, but no more than five times the marked maximum supply: }$ }+ _& x% _6 r3 [
pressure from an external source and no more than five times the pressure setting of a" ^! u: N0 s8 q' H E
pressure-relief device provided as part of the assembly.
; |3 r+ T1 Q. Y( Kb) Five times the marked maximum supply pressure from an external source, except as
( A, S8 b$ I7 X/ a; G! `$ sprovided in (a).
, i0 d; h' {1 O; hc) Five times the pressure setting of a pressure-relief device provided as part of the assembly.
* f1 o! ~* O4 o; J! n1 Ed) Five times the maximum pressure that can be developed by an air compressor that is part of
\$ V9 @/ ^9 w- Wthe assembly, unless the pressure is limited by a pressure-relief device in accordance with (a).
" C$ G/ o) v+ \2 Q: c2 Ie) Five times the working pressure marked on the part.# w. W6 g, D/ V$ r9 ~% a0 s1 J) a% J
29.4 A test need not be performed to determine whether a part complies with the requirement in 29.3 if
5 I+ f$ c: o* K1 ystudy and analysis indicate that the strength of the part is adequate for the purpose as a result of its
2 @* r0 a* A* o5 i1 i# G% gmaterial and dimensions – for example, copper or steel pipe of standard size and provided with standard% u& \5 B; J9 D6 c) F0 t
fittings might be considered to have adequate strength.- H1 l0 O$ x4 h4 D( T C* d' K+ W
29.5 A pressure vessel bearing the ASME code inspection symbol (²H², ²M², ²S², or ²U²) is considered
3 Q2 H; ]* F7 k4 l. lto comply with the requirement in 29.3 if the vessel is marked with a value of working pressure not less9 E$ [! B- E; ~4 f$ h
than that to which it is subject during normal or abnormal operation.' B4 D- {) _6 O% A& T
29.6 If a test is necessary to determine whether a part complies with the requirement in 29.3, two samples; b; t0 f8 `: a* ^/ W( x
of the part are to be subjected to a hydrostatic-pressure test. Each sample is to be filled with water as to* w2 A1 }: q; c$ Q
exclude air and is to be connected to a hydraulic pump. The pressure is to be raised gradually to the
u$ X' \# a" v1 e6 Ispecified test value and is to be held at that value for 1 minute. The results are not acceptable if either9 u. z9 a% k7 e% }
sample bursts or leaks, except as indicated in 29.7.$ Z! L' e7 B% h; ^. e3 a( G
29.7 Leakage at a gasket during the hydrostatic-pressure test is not unacceptable unless it occurs at a5 N4 e3 N' t* n; V' H2 O
pressure 40 percent or less of the required test value.
5 n! F; z2 r( ^7 i& [29.8 A means for relieving pressure shall be provided for all parts in which pressure might be generated9 F1 L9 q% F0 n4 B
in the event of fire.2 L9 x4 n6 _8 i& t/ ^
29.9 Pressure-relief devices (see 29.15), fusible plugs, soldered joints, nonmetallic tubing, or other
3 Y: A; t/ x K# t( lpressure-relief means or the equivalent may be employed to comply with the requirements in 29.8., P4 q o8 {; r3 \( E
29.10 There shall be no shut-off valve between the pressure-relief means and the parts that it is intended
6 K! F. ^" [7 U, v1 D6 Mto protect." x! V+ q( k, S) [. _; B, @2 W
29.11 A vessel having an inside diameter of more than 3 inches (76.2 mm) and subject to air or steam
& K3 @5 V5 r/ i# w0 p: tpressure generated or stored within the appliance shall be protected by a pressure-relief device.9 J/ h k( `6 k$ @8 f( _7 G
29.12 The start-to-discharge pressure setting of the pressure-relief device shall not be higher than the% K$ B4 R h% e
working pressure marked on the vessel. The discharge rate of the device shall acceptably relieve the6 |9 \& W4 _" W* n+ k) G
pressure.
( W' h3 ~; R% h3 b& U29.13 A pressure-relief device shall comply with all four of the following:8 B2 z0 U0 I: D8 g
a) Shall be connected as close as possible to the pressure vessel or parts of the system that it
5 G7 }5 C8 h& R% ^2 Yis intended to protect;
) s% ]* W2 G% ?, z! T1 S$ {b) Shall be installed so that it is readily accessible for inspection and repair and cannot be
: v# k' @% D, g. U6 j7 Treadily rendered inoperative;% a4 G$ f/ n6 ?# G/ w( Z! _$ I: @
c) Shall have its discharge opening located and directed so that the risk of scalding is reduced
- ~) d/ D9 m1 qto a minimum; and" c3 I8 p8 H5 R9 o
d) Shall have its discharge opening located and directed so that operation of the device does
1 P7 f- ?/ p f$ V- n$ S Nnot deposit moisture on bare live parts or on insulation or components affected detrimentally by
1 n. u% c' C/ ~7 k) L3 u) A1 x* f" ?moisture.
* o# _3 W9 j0 P3 H# g7 ^29.14 A pressure-relief device having an adjustable setting shall be judged on the basis of its maximum
1 [8 _0 i# Y. g) wsetting unless the adjusting means is sealed at a lower setting.9 O8 d- h8 n2 z2 i
29.15 A pressure-relief device is considered to be a pressure-actuated valve or rupture member intended6 H* T$ y! n# H: ]
to relieve excessive pressures automatically.
& k. p1 x! `, x# f: _* W& x5 C29.16 Where a pressure relief device is required, the control responsible for limiting the pressure in the
0 z: { {# H! D8 Dvessel shall be capable of performing under rated load for 100,000 cycles of operation and shall prevent, K* |) @ {% B& k
the pressure from exceeding 90 percent of the relief device setting under any condition of normal
: |+ y' \8 ]& e1 O0 t; |% soperation. |
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