S9074-AR-GIB-010/278
8. POST WUD HEAT TREATMENT
8.1 General. Unless otherwise specified in the qualified welding or heat treatment procedure, post- weld thermal stress relief heat treatment shall be performed in accordance with Table VI, 6.4. and this section.
8.2 Special Requirements
8.2.1 Dissimilar metal joints. When parts of two different S-number groups are joined by welding, the post-weld heat treatment temperatures shall be selected on the basis of preserving the mechanical properties of the more critical of the two materials for the application concerned. 8.2.2 Post-weld heat treatment for different thicknesses of plate in pressure vessels. When the welded joint connects parts of pressure vessels that are of different thicknesses, the thicknesses to be used in applying the requirements for post-weld heat treatment shall be as follows: (a) The thinner of two adjacent butt-welded plates including heat to shell connections. (b) The thicker of the shell or head plate in connection to the intermediate heads. (c) The thickness of the steel in connections to tube sheets, and flat heads, covers or similar constructions. (d) The thickness of the shell or head plate in nozzle attachment welds. (e) The thickness of the nozzle neck at the joint in the nozzle neck to flange connections. (f) The thickness of the pressure part, at the point of attachment, where a non-pressure part is welded to a passion part.
8.3 Ferrous material. Post-weld heat treatment for ferrous materials shall be in accordance with table VI.
8.4 Nonferrous material. Post-weld heat treatment for nonferrous materials shall be in accordance with 6.4.1 through 6.4.6.
8.5 Post-weld heat treatment procedures (furnace).
8.5.1 Loading temperature. The furnace temperature shall not exceed 800°F at the time weldment is placed in it.
8.5.2 Rate of heating. The rate of heating above 800°F shall be not more than 400°F per hour divided by the maximum metal thickness of the component or vessel in inches, but in no case more than, 400°F per hour (see 8.5.7)
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