CAUSE ANALYSIS OF FRACTURE OF OUTLET PRESSURE GAUGE JOINT OF PRODUCED WATER REINJECTION PUMP IN OILFIELD

The failure of the outlet pipeline and its accessories of high-pressure pump in oil field has great harm. Taking the fracture accident of pressure gauge joint at the outlet of produced water reinjection pump in an oil field as an example, this paper studied the causes of fracture failure of the joint, experimentally detected and analyzed the chemical composition, hardness, metallographic structure and inclusions of the fracture joint, observed and analyzed the macro morphology of the fracture, and observed the micro morphology of the fracture by scanning electron microscope and energy spectrum analysis, The structure and service conditions of the joint are studied. The results showed that the fracture of the joint was caused by chloride stress corrosion cracking. The presence of H2S in the medium played a certain role in promoting the corrosion cracking. There was no fillet transition at the joint between the external thread undercut and the nut, resulting in stress concentration, which made the joint fracture at this place. It is recommended to test such pipe fittings in service in the same environment to eliminate potential safety hazards of the pipeline.