Temper embrittlement, weld metal

Bruscato, R., Temper Embrittlement and Creep Embrittlement of 2.25Cr-lMo Shielded Metal-Arc Weld Deposits, Weld. J. 49, Res. Suppl., pp 148-s -156-s, April 1970. 

Brittle fracture is always a concern with heavy wall vessels. An 80 to 100°F (27 to 38° C) minimum hydrostatic test temperature is often specified to minimize the possibility of brittle fracture during hydrostatic testing. To minimize the possibility of brittle fracture of heavy wall reactors during start up and shutdown, reduced pressure below 200 to 300° F (90 to 150°C) is usually specified. Typical limitations are 40% of the design pressure or 20% of the original hydrostatic test pressure. With the advent of temper embrittlement resistant steels and weld metal, some refiners feel reduced pressure is only required below 100°F (38°C). 

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