Corrosion control of subsea production control systems - 20 years of experience

摘要

During the initial period of subsea production, improper materials selection resulted in frequent damage by corrosion causing sudden loss of production control. In many cases, materials like AISI 316 stainless steel, which had performed adequately for offshore topside production control, failed by corrosion in a relatively short period of time. Later on when the needs for corrosion control by cathodic protection were recognised, inefficient provisions for electrical continuity still continued to cause sporadic damage to critical components. In addition, improper design and/or lack of quality control during fabrication have lead to premature degradation of corrosion control systems, including excessive anode consumption and coating degradation. Even when corrosion control had been successful subsea, poor preservation procedures have sometimes lead to severe corrosion damage of components during storage. The paper gives examples of such failures and gives advise to optimise corrosion control of subsea production control systems.