If user combines the two in actual operating process, frequency of mechanical rapping can be reduced and the impact on heating surface welded junction of mechanical rapping position can be relieved.

If the valve body material can be welded, but very different thermal expansion coefficient, or changes in operating temperature range of a larger thread junction closure weld must be honey.

Based on plenty of account data, engineering estimated formulas for plastic limit internal pressure were fitted for welded pipe branch junction with incomplete penetration along intersecting line.