The welded joints of all welded valve bodies are generally designed for narrow gap thick wall submerged arc welding, such as Class600, 20 inch pneumatic ball valve, and 44mm, C1ass900, 48 inch pneumatic ball valve with 140mm welding wall thickness. It is a tubular welded joint with extra thickness. Thick wall multi-layer welding process is a process of repeated heating and cooling of metal materials, which leads to nonuniformity and deterioration of the welded joint structure, high residual stress, and even welding defects. Welding is the last process after the assembly of the product. There are non-metallic sealing materials rubber and polytetrafluoroethylene plastic in the valve chamber, so post welding heat treatment is not allowed.

Fireproof structure: according to the working conditions and user needs, the ball valve can be designed as a fireproof structure. The fire resistance design of the ball valve shall comply with the provisions of API607, JB/T6899 and other standards. Once the soft seal ring is burned due to fire, the fire protection structure of the ball valve can prevent a large amount of leakage of media and prevent further expansion of the fire.