5、 Conclusion All welded pneumatic ball valve is a typical narrow gap submerged arc welding product, which involves many aspects of knowledge such as material science, welding technology, automatic development of welding equipment, 3D thermal elastoplastic finite element calculation, and design of pipeline pneumatic ball valve. With the construction of a large number of national key pipeline projects such as the West East Gas Pipeline Project, the West Crude Oil and Product Oil Pipeline Project, and the Sichuan East Gas Pipeline Project, the progress in localization technology, equipment, manufacturing and process of all welded pneumatic ball valves has been greatly promoted, and the wells are gradually becoming mature and perfect, starting to develop in the direction of large diameter and high pressure. Through the analysis of the influencing factors of weld formation and weld metal mechanical properties, as well as the welding test results, the valve body structure, weld groove form and valve seat structure are reasonably designed, the chemical composition of the valve body raw materials is strictly controlled, the reasonable welding wire flux and process parameters are selected, and the narrow gap groove multi pass and multi-layer welding is adopted, The interlayer temperature in the welding process shall be controlled timely to fully meet the welding production requirements of all welded pneumatic ball valves.

Precautions in the application of pneumatic butterfly valve
Precautions during operation: 1. Sealing connection of non-metallic flat gasket
1) Cut and peel the protective sleeve (covered pipe) away from one end of the buried pipe and use special tools to cut the covered pipe about 50 mm long along the circumference, so as to expose the metal bellows at one end;
2) If the edge of one end of the corrugated pipe has obvious flash, burr or ellipse, use a pipe cutter to cut 1-3 wave rings along the bottom of the corrugated pipe at the exposed end until the inner hole at one end of the corrugated pipe is rounded. If the exposed end length is insufficient after cutting the corrugated pipe, continue to cut and peel the covered pipe to supplement the exposed end length (not less than 50mm).
3) Process the flange and install the connecting nut into the exposed end of the bellows, and then process the flange with the special tool for flange processing. The flange is made by flattening the three waves of the bellows. 4) The seal is connected to the flange flat gasket with the seal ring, and then connected to the joint or valve with the joint nut.