Stress Corrosion Cracking of an Electrohydraulic Oil Pipe
- 27 Downloads
Cracking of an oil inlet pipe in an electrohydraulic governing system was detected and analyzed to determine its failure mechanism. Microscopic analysis methods, such as the scanning electron microscopy and energy-dispersive X-ray spectrum, were applied to obtain the effective information. Visual and micro-examination showed that the pipe suffered a brittle cracking at the elbow part. Corrosion pits and branched cracks had formed in the outer surface of the pipe. The element of chlorine was detected both in the corrosion pits and the corrosion products inside the cracks. In addition, the cracks were found initiating from the bottom of the corrosion pit. Transgranular cracking feature was identified for the cracks. All the collected evidences suggested that the EH oil pipe fractured due to the combination of a chloride pitting corrosion and a stress corrosion cracking failure.
KeywordsStress corrosion cracking Pitting corrosion EH oil pipe Austenitic stainless steel Failure mechanism
This work was supported by the National Natural Science Foundation of China (Grant Nos. 11404192 and 11605106), the Key Research and Development Project of Shandong Province, China (Grant No. 2017GSF220004), the Shandong Province Special Grant for High-Level Talents (Taishan Scholar), and the research fund of Shandong Academy of Sciences (Grant Nos. 2017QN001 and KJHZ201805).
- 1.Z.H. Wang, S.C. Guo, Research on maintenance optimization for steam turbine digital electro-hydraulic control system, in International Symposium on Intelligent Information Technology Application, vol. 2 (2009), pp. 345–348Google Scholar
- 2.Z.G. Wei, C.L. Gao, The digital electro-hydraulic (DEH) control system of turbine and its application. Autom. Petro Chem. Ind. 1, 35–37 (2006)Google Scholar
- 11.J.D. Dobis, J.E. Cantwell, M. Prager, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry (American Petroleum Institute, Washington, 2003)Google Scholar
- 15.X.Q. Kang, Z. Sun, Failure analysis of stainless steel bellows used in heat supply pipeline. Press. Vessel Technol. 24, 38–42 (2007)Google Scholar