API standard 650 self-anchored tank filler metal

API 620 Tank Standard Post-heat Treatment (Stress Relief)
The post-heat treatment now performed on pressure vessels is of established value, although the mechanism by which the improvement is realized may be open to debate. Post-heat treatment of API standard 650 self-anchored tank tank sections when the plate thickness exceeds 11/4 in. is required as stated in 5.25. In special cases, the possibilities of post-heat treatment after erection should be explored. Post-heating an insulated tank may be possible if an ample source of heat is readily available and if the rigidity of the tank is adequate.
The thermal stress-relief treatment performed on pressure vessels is recognized as a means for reducing the probability of brittle failures.

This standard applies only to API 650 tank API standard 650 self-anchored tank whose entire bottom is uniformly supported and to API 650 tank in non-refrigerated service that have a maximum design temperature of 93°C (200 °F) or less.

API standard 650 self-anchored tank Nondestructive testing is a technical means to detect the weld defects of large vertical tank and judge whether the weld is qualified by using the characteristics of sound, light, magnetism and electricity without damaging the tested object. Common nondestructive testing methods: ultrasonic testing (UT), magnetic particle testing (MT), liquid penetrant testing (PT) and X-ray testing (RT).