A333 grade 1 pipe API 650 larger diameter tanks

The hardness of the welds contacting these environments, including the heat-affected zones, shall be considered. The weld metal and adjacent heat-affected zone often contain a zone of hardness that is well in excess of a value of 22 on the Rockwell C scale and could be expected to be more susceptible to cracking than would unwelded metal. Any hardness criteria shall be a matter of agreement between the Purchaser and the API 650 larger diameter tanks manufacturer and shall be based on an evaluation of the expected hydrogen sulfide concentration in the product, the possibility of moisture being present on the inside metal surface, and the strength and hardness characteristics of base metal and weld metal.

Before pressure test, the main drain hose system of API 650 petroleum storage tank floating roof should be thoroughly flushed. Provide blind flanges, gaskets and bolts required for the API 650 larger diameter tanks test (other types of covers are also required if necessary). Covers for maintenance shall be provided in accordance with the interfaces specified by API 650 petroleum storage tanks, and these seals shall remain in place after the test; and for those interfaces that are not provided for maintenance covers, the covers can be removed after the API 650 larger diameter tanks test.

Define the welding sequence of API 650 larger diameter tanks bottom plate: the welding sequence of metal vertical storage tank shall be carried out according to the procedure required by the welding scheme. Spot welding shall be consistent with the formal welding requirements, and no spot welding shall be carried out for the weld not welded. Back bar should be added to prevent deformation when welding the full length seam of middle plate, butt joint of edge plate and turtle shell joint.