S9074-AR-GIB-010/278
Table VI-Post Heat Requirements for Welded ferrous alloys - Continued
Applicable supplementary provisions and exceptions
Pressure vessels, turbines classes A-F, A-LT, A-1, A-2, A-3, A- 4, T-1, and T-2 Thermal stress relief is required for all classes without exception. Thermal stress relief is mandatory for Mn-Mo steel welded fabrication in all classes; it is not mandatory for class A- 3 when carbon molybdenum steel is welded in thicknesses up to and including 5/8 inch. Thermal stress relief is required for all thicknesses 5/8 inch except that it is not mandatory for nonpressure type attachment welds to pressure parts when the latter’s carbon does not exceed 0.25 percent, and fillet welds that have throats 1/2 inch and less in thickness are used.
Holding Tempera ture *F 2/, 3/
Material Group Number
Material Identifica tion 1/
Machinery class M 1/
Piping Class P
1000- 1050
Thermal stress relief shall be performed where required for dimensional stability. Thermal stress relief mandatory should S-3 be used to fabricate class M machinery parts.
S-2 Quenched and Tempered Carbon steel
Not applicable
6/, 4/ S-3 Carbon
Thermal stress relief required for welded carbon- molybdenum piping only when one or more of the following apply:
1100- 1250
Molybdenu m alloy steels chromium <3/4 percent
(a) carbon is over 0.25 percent
1100- 1175
6/, S-3A Mn-moly
(b) wall thickness is in excess of 5/8 inch
(c) pipe size exceeds 4 inches maximum nominal outside diameter.
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