Wuhan University of Technology and China Classification Society determined the best welding process from two different welding processes without heat aging treatment through CTOD value evaluation. According to the CTOD (Crack Intermittent Opening Displacement) test results, Tianjin University has successively adopted the BS7910 standard proposed by the British Standards Association and the SINTAP structural integrity assessment method proposed by the European Community to assess the surface cracks at the weld toe of EH36 pipeline steel welding joints.

Differences between V-type regulating ball valve and pneumatic butterfly valve:
(1) Small size, small mass, easy to install, its mass is only 1/3~1/4 of that of the gate valve at the same level, and its height and width are only 1/3 of that of the gate valve at the same level;
(2) The cutting performance is better than that of gate valve and globe valve;
(3) Good regulation performance, not only low pressure drop, but also wide regulation range;
(4) Simple structure and easy maintenance;. Easy to configure automatic control actuator;
(5) Compared with gate valves and globe valves of the same temperature and pressure rating, butterfly valves are cheap.