Pipeline ball valve process characteristics
Valve body welding
Our company has two automatic welding machines that can weld 56" pipeline ball valves to complete the welding of the girth weld. The low-stress submerged arc welding process is adopted to control the welding residual stress to the lowest level and the welding deformation to be controlled within the machining tolerance range. And effectively control the welding temperature field to ensure the safety of non-metallic sealing materials. Imported welding wire can be used to match the valve body material, and imported flux that can be free of post-weld heat treatment is selected.
The valve body materials are evaluated in accordance with ASME BPV Volume XI.
Carry out fracture toughness test according to BS7448 Part2, refer to API1104 Appendix A, Det Norske Veritas DNV-OS-C401 standard to evaluate the possibility of heat treatment-free after welding of welded joints.
Relief of welding residual stress
All-welded pipeline valves adopt mechanical stress relief methods to reduce the residual stress level of the entire valve body. At the same time, ultrasonic (mg energy) stress relief method is used to eliminate the residual stress on the weld surface.
Surface treatment of internal parts
All the surface of the sphere, valve seat, support plate, valve stem and other internal parts of all pipeline valves are nickel-plated, and the thickness of the nickel-plated coating is not less than 75μm. Chrome can also be plated according to user requirements.
Spherical grinding
The sphere adopts a five-axis CNC ball grinding machine imported from Italy for envelope grinding. The precision and roundness of the sphere after grinding are less than 2μm, and it is measured on a three-dimensional coordinate measuring instrument.