| CAI Rui,WU Peng,ZHAO Jin-long,LI Yun,LI Fa-gen,XU Xiu-qing.Corrosion Failure Analysis of L245 Gathering Pipeline[J],48(5):58-64 |
| Corrosion Failure Analysis of L245 Gathering Pipeline |
| Received:December 15, 2018 Revised:May 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.05.009 |
| KeyWord:gathering pipeline inner surface corrosion electrochemical corrosion dissolved oxygen corrosion corrosion perforation |
| Author | Institution |
| CAI Rui |
1. Xi′an Jiaotong University, Xi'an , China; 2. State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, Xi′an , China |
| WU Peng |
3. PetroChina Jidong Oilfield Company, Tangshan , China |
| ZHAO Jin-long |
3. PetroChina Jidong Oilfield Company, Tangshan , China |
| LI Yun |
1. Xi′an Jiaotong University, Xi'an , China |
| LI Fa-gen |
2. State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, Xi′an , China |
| XU Xiu-qing |
2. State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, Xi′an , China |
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| Abstract: |
| The work aims to determine the corrosion features, corrosion type and corrosion mechanism by analyzing the corrosion failure behavior of some gathering pipeline so as to guide the corrosion treatment and extend the service life of pipeline. The corrosion location and macroscopic characteristics of the inner and outer walls of pipeline were analyzed through geometric dimension measurement and macroscopic observation. The materials were inspected through chemical composition analysis and metallographic analysis. Samples were taken from the corrosion perforation part and microscopic morphology and energy dispersive spectroscopy of the corroded surface were analyzed by scanning electron microscopy (SEM). The corrosion products were analyzed by X-ray diffraction. The chemical composition of the perforated pipeline conformed to GB/T 9711—2017 standard, and there was no abnormal metallographic structure. The corrosion was concentrated on the inner wall the corrosion location was between 4 o’clock and 8 o’clock. There was basically no corrosion on the outer wall of the pipeline. The corrosion products were lamellar and showed a multi-layer structure. The outer layer was relatively loose and mainly composed of C, Si, O, Ca and other elements, which were dirt and scale adhered to the surface. The middle and inner layers were relatively dense and mainly composed of Fe, O elements, and contained a certain amount of Cl elements, which were the main components of corrosion products. X-ray diffraction results showed that the corrosion products were mainly composed of Fe3O4 and FeOOH. The corrosion and perforation of the inner surface for the pipeline are mainly caused by the laminar flow of oil and water, the deposition of water at the bottom of the pipeline and the formation of electrochemical corrosion. The basic corrosion type is dissolved oxygen corrosion. Local corrosion is accelerated by the Cl¯ and destruction of the corrosion product film on the surface. |
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