生产分离器底部腐蚀坑的形成原因及预防措施

Reason Analysis and Prevention Measures against Corrosion Pits at Bottom of Production Separator

在对某沙漠油田油系统2台生产分离器检验合格使用5 a后的再停产检修期间,发现其罐内底部存在大面积腐蚀坑。腐蚀坑不规则分布在罐底焊缝和母材上,最深达12 mm。为了找到腐蚀坑形成的主要原因,本文从罐体结构、内涂层和牺牲阳极联合保护及使用环节3个方面进行了分析。结果表明,腐蚀坑的形成与水腔罐底污水静置时间长、淤泥沉降附着量大、内涂层和牺牲阳极联合保护失效以及排污周期长等因素密切相关。在此基础上,本文有针对性地提出了预防腐蚀进一步扩展的措施。研究结果可为相关压力容器的腐蚀预防与控制提供借鉴。

An overhaul was carried out for two production separators in an oil field at desert. These two separators were testified to be qualified 5 years ago. However, in this overhaul, a large area of corrosion pit is found at the bottom of the tanks of the separators. The corrosion pits are irregular at the weld joint and the base metal, and the deepest of the pit is 12 mm. In order to reveal the main reasons of the corrosion pits, this article analyzes three factors including the tank structure, inner coating and sacrificial anode protection. The results show that the formation of the corrosion pit is closely related to the long-time residence of the sewage at tank bottom, the increase of sludge sedimentation and adhesion, the synergic protection failure of the inner coating and the sacrificial anode and the long pollutant-discharging cycle. Furthermore, some measures for corrosion prevention were put forward. The research results can provide a guide for corrosion prevention and control of the related pressure vessels.