Failure Analysis of Double Male Joint in Oil Well

A double male joint was broken in oil well during elevation.Through the analyses of chemical composition,mechanical properties,micro-fracture and metallographic examination,pit corrosion test,etc,the broken reasons of the double male joint were analyzed.The existence of corrosive media such as S and Cl on the inner wall of the double male joint induced pitting corrosion firstly and then hydrogen induced cracking from the pit bottom.When the external force was loaded,the fracture occured at the site of serious corrosion.