Electronic Survey Helps Assure Integrity of Offshore Pipelines

Abstract

Abstract On-land practices of excavating and sampling for detection and evaluation of corrosion in pipelines are, at best, inadequate. Such a practice regarding offshore pipelines would be very impractical for many reasons. However the need and concern for corrosion evaluation of pipelines in that area are just as great if not more so than land lines. A more detailed method developed over the past few years is now in use for evaluating corrosion and mechanical damage in offshore pipelines. Electronic surveys have been performed on several major offshore lines. Data provided by the surveys enables the operator to locate, evaluate, and through subsequent surveys, monitor corrosion and other conditions. Base line surveys were run on two lines from platforms in the Santa Barbara Channel to shore immediately after construction was completed. Subsequent surveys have been performed to monitor and assure the integrity of the pipelines. Other surveys have been made on offshore lines in or near metropolitan areas when leaks could seriously affect public opinion. Electronic surveys may be performed on offshore lines under most conditions and without interruption of pipeline operations. TEXT Almost anything that would adversely effect the integrity of a pipeline has been of concern to the operators of those pipelines. In many cases, pipeline companies have taken elaborate steps to protect the lines from damage or deterioration. Pipe surfaces are frequently coated with a corrosion barrier, cathodic protection systems are installed to counteract corrosion processes, and other devices are used to further protect the pipe. In spite of that protection and attempts to safeguard systems, pipelines become damaged and/or otherwise deteriorate in some manner. It is believed that most deterioration occurs in the form of corrosion. Even with the application of corrosion prevention coatings or devices, some corrosion degradation frequently develops. Pipeline corrosion control personnel work diligently to monitor conditions developing in their pipeline and upgrade the protective installations. In addition, pipe surfaces are frequently examined when and where possible. On-land procedures of excavating sections of buried pipeline have been an extensive practice for many years in order to observe pipe surfaces and evaluate corrosion conditions. For the industry, this practice requires the use of many men at the expense of many man hours and at best, the practice can only expose a limited portion of a major line. Since large sections of a line may go unexamined by this method for a time, extensive damage could go undetected and result in a line failure. Such a practice on offshore pipelines is basically impractical because of the water environment and other factors.