Failure analysis of weld cracking of gas gathering pipeline in dewatering station

Abstract There are a lot of welded joints in the shale gas collection pipeline, so failure risk production line is very high. A leak has occurred pipeline dewatering station, and order to find out causes provide technical support for safe transmission, macroscopic analysis, non-destructive testing (X-ray flaw detection), mechanical properties, metallurgical analysis were performed on failed pipe section, CFD method was used further analyze mechanism ring weld pipe. The yielded height significantly greater than standard minimum requirement. Non-destructive showed large number cracks with varying degrees extension along circumference inner surface weld. chemical composition properties met requirements. microstructure base metal standard. no inclusions, holes, unfused areas, or other welding defects zone. originate from fusion zone, there intergranular microcracks. simulation results show that although stress concentration caused by does not directly lead cracking, under influence concentration, tend sprout at coarse grain organization zone can easily propagate throughout wall thickness, leading crack damage. Several suggestions prevent such proposed avoid occurrence similar accidents.