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- Title
Failure Analysis of Leakage for Insulating Joint at Natural Gas Pipeline.
- Authors
Wang, G. F.; Deng, B.; Zhang, H. B.; Yang, F. P.; Zhang, L.; Ren, G. Q.
- Abstract
Insulating joint is an essential component for pipeline cathodic protection system. During the safety confirmation before the excavation of the station foundation pit, a pipeline company found that the insulating joint was failed due to leakage. In order to determine the causes of leakage, data verification, tests and failure component analysis were carried out. The results show that: (1) the leakage point cannot be detected by NDT, hydraulic pressure test, and hydraulic pressure + bending test, and the gas leak test in the water container demonstrates two leakage points on the fixing sleeve of the insulating joint; (2) the insulating joint has an unfilled cavity, and the mechanical holes on the fixing sleeve are blocked by bolts, which are inconsistent with the assembly drawing; and (3) the leakage of the insulating joint was caused by the sealing failure during assembly or service, which allowed some gas to gather in the cavity between the flange and the fixing sleeve and then leak through the gap between the mechanical hole and the bolt. Accordingly, it is suggested that (1) manufacturers should strictly follow the process when producing insulating joints, the product structure be consistent with the assembly drawing, the product inspection be done according to requirements, and NDT be done on all welding areas; and (2) the insulating joint be leak-tested in the water container where possible.
- Subjects
FAILURE analysis; NATURAL gas pipelines; PIPELINE failures; CATHODIC protection; LEAKAGE; WATER leakage
- Publication
Journal of Failure Analysis & Prevention, 2022, Vol 22, Issue 1, p292
- ISSN
1547-7029
- Publication type
Article
- DOI
10.1007/s11668-021-01299-0