Failure Analysis and Treatment Stress Corrosion Cracks in Liquefied Petroleum Gas Spherical Tank

The operational safety of liquefied petroleum gas spherical tank is very important. Through the comparison of the previous nondestructive testing results about in-service spherical tank, combined with the composition analysis about original oil in the tank and metallographic examination about corroded parts, analysis on cracks generated in the spherical tank was carried out. It is found that the synergism effect between stress corrosion cracking caused by hydrogen sulfide and stress-guided-hydrogen induced cracking mainly accounts for the crack genration. According to the testing results, corresponding treatment methods for cracks and prventive measures against corrosion cracking were proposed. After subjected to inspection and repair, the spherical tank was placed in service for a period of time and reopened for regular inspection. The inspection results verify the effectiveness of the proposed treatment method, which provides a reliable reference for the treatment and prevention of this kind of stress corrosion cracking.