管道工程技术研发、技术服务；管道检测；压力容器和压力管道监理；量规检测；机械设备及配件销售、安装、调试、维修；化工产品销售；专业设计服务；工程监理服务；工程技术咨询服务。（依法须经批准的项目，经相关部门批准后方可开展经营活动）
As more submarine pipelines are put into service and operated for extended periods,the issue of corrosion in ag-ing submarine pipelines has become increasingly severe.However,maintenance costs for offshore oil and gas fields are typi-cally constrained,despite their high production pressures,leading to an urgent need for low-cost and highly efficient in-situ repair technologies for these pipelines.To address this need,this paper presents a systematic review of the characteristics and challenges associated with traditional repair technologies for submarine pipelines.It particularly focuses on the features and applications of three new in-situ repair technologies:lined composite hoses,the insertion of reinforced thermoplastic pipes(RTP),and in-situ internal coatings.Research results are summarized as follows:① The repair technology based on lined composite hoses can effectively prevent the progression of corrosion in repaired pipelines by isolating the conveying medium from the pipeline itself,thereby extending its service life.However,the construction process is challenging,and the technology is relatively complex.② The insertion of RTPs as a repair technology allows the RTPs to replace the submarine pipeline for medium transmission while maintaining resistance to corrosion from both the medium and seawater.Nonethe-less,the reduction in diameter of the RTPs complicates the insertion process and presents technological challenges.③ The repair technology utilizing in-situ internal coatings is suitable for pipelines with remaining wall thickness and strength that still meet design and operational requirements,regardless of their intended use,including the transportation of water,gas,and oil.The concluding section further discusses the application scenarios and future research directions for these three new in-situ repair technologies,providing valuable insights for their continued research and application.
The B10 copper-nickel alloy pipeline used for seawater transportation on a certain platform was found to have corrosion perforation at the weld joint between the elbow and the flange during a shutdown inspection.In this study， the failure mechanism of corrosion perforation was analyzed using macroscopic morphology observation，scanning electron microscopy (SEM)，energy-dispersive spectroscopy (EDS)，X-ray diffraction (XRD) and metallographic examination.Results showed that “sugar cube”-like intergranular corrosion morphologies were commonly observed at the bottom of corrosion pits on the flange， in erosion-wear areas， corrosion grooves， perforated regions and at the bottom of corrosion pits on the elbow.Locally， a “stepped” exfoliation morphology was observed， where grains were progressively stripped layer by layer.The preferentially corroded grain boundaries formed a circuit， and the surrounded grains were selectively denickelized and dissolved， resulting in grain spalling.The reduced hardness and coarse columnar grain structure of the flange further decreased the material’s corrosion resistance.The corrosion perforation of the copper-nickel alloy pipeline occurred in the erosion-sensitive zones and the weld heat-affected zones with the poorest corrosion resistance.This failure was the result of the synergistic effects of erosion wear， intergranular corrosion and selective dealloying.Enhanced corrosion monitoring is recommended for similar locations in service pipelines.
