In the construction of gas interruption joint of natural gas pipeline

it is strictly forbidden to group welding joints by force.Construction workers often have doubts about this prohibition. They think that in the process of welding joint set alignment

as long as the welding joint can be aligned

non-destructive testing is qualified. Feeling forced group only increases the residual stress of the weld

and has little effect on the safe operation of the pipeline. Therefore

the simulated forced group welding test is carried out. Through the analysis of the theoretical data such as bending and impact of the qualified simulated weld specimens by conventional non-destructive testing

it is concluded that the hardness of the forced group welding joint increases and the toughness decreases

and it is easy to cause micro-cracks in the welding process

resulting in cracking failure after commissioning. It can not effectively satisfy the conclusion of safe operation of pipeline.