ISO 630 grade E275 quality B plates API 650 carbon steel storage tanks

Preheat Treatment
Many laboratory tests have shown preheat treatment of carbon steel to 300°F-400°F to be the equivalent of the post-heat treatment at no less than 1100°F insofar as the physical properties of the weldment are concerned.40,41 Some tests have indicated a slight advantage of the post-heat treatment. Most of the tests have been made on plates 3/4 in. - 1 in. thick; results must be viewed with caution if preheating is applied appreciably beyond this thickness range. However, for all practical purposes, improvement resulting from preheating is sufficiently well established so that preheat should be considered for field fabrication of API 620 crude oil tank plates over 3/4-in. thick whenever toughness of the tank API 650 carbon steel storage tanks is highly desired and the thermal post-heat treatment is impractical.

API 650 is the standard for welded tanks for oil storage. It specifies the API 650 carbon steel storage tanks design, manufacturing, welding, inspection and installation requirements of oil tanks. API 650 is widely used in storage tanks with internal pressure less than or equal to 2.5 PSI.

Before welding the API 650 carbon steel storage tanks, the professional skills of the welding personnel shall be fully assessed to ensure that the operators meet the corresponding welding qualifications. According to the technical standards, scientific and feasible process requirements are actually formulated. In the process of welding the edge plate of API 650 carbon steel storage tanks, electric welding is required on one side of the edge plate, so that the edge plate has a free shrinkage effect and greatly reduces the residual stress of the welding seam.