东洋阀门（上海）有限公司

I am sure you have seen all-welded ball valve, are aware of welded joints are generally designed for narrow gap SAW thick, there is the all-welded body mostly large thickness of tubular welded joints. We definitely want to know why this is, right?

1: heat treatment technology

Thick-walled multi-layer welding process is a metallic material repeatedly heating and cooling process, resulting in uneven and poor quality of the welded joint, resulting in a higher residual stress, even welding defects. Welding is the product of the final steps of the assembled valve cavity has a non-metallic material such as rubber and PTFE sealing plastic, after-weld heat treatment is not possible.

2: The joints treated

The design of welded joints in the body, for aligning and positioning, in the presence of an annular weld toe assembly slot, the slot in the internal pressure and external loads, would produce several times the normal working stresses dry stress concentration, the same so engineers difficult to handle.

Stress of welded joints of the body concentrated root gap, residual stress, poor quality of the organization to become the weak link in the body structure, valves for domestic sector is concerned, but there are no reports of any solution to this problem has become this product a hidden structural integrity of the border.