The maximum principal stress of the 20in 600Lb all welded body pneumatic ball valve is 15MPa based on 1.5 times of the rated working pressure, and the maximum axial strain is 728 according to the finite element calculation με (i.e. 0.000728 ε）， If the minimum acceptable CTOD=0.005in (0.1225mm) given in Appendix A of API 1104 is considered, the maximum defect size limit is 0.3in, equivalent to 7.6mm. The measured CTOD=0.008in (0.196mm), and the corresponding allowable defect size is 0.45in (11.4mm), according to the requirements of JB4730-94 Class 1 pressure vessel, the allowable defect size is less than 0.15in (3.765mm), so the actual joint still has a relatively high safety margin. NDT for all welded valve body welds shall be carried out according to the requirements of Class 1 pressure vessel in JB4730-1994, and the weld defect size shall be less than 0.15in (3.675mm). Therefore, when the welded joint of the fully welded valve body meets the CTOD fracture toughness value of more than 0.005 in (0.1225 mm), and the NDT of welds meets the requirements of JB4730-94 for Class 1 pressure vessels, it can be recognized that the post weld heat treatment free process is safe and reliable.

Double jacket flange hose Double jacket flange hose
Applicable to: aerospace, petroleum and natural gas, vehicle and ship machinery manufacturing, metallurgy and chemical industry, transportation, electricity, central heating, refrigeration, nuclear energy, water power and other industries.