On-stream inspection techniques exist that inspect for Corrosion Under Pipe Supports (CUPS), also known as Touchpoint Corrosion. These include Electromagnetic Acoustic Transducer (EMAT), Guided Wave and others. These methods are effective at evaluating corrosion severity, especially at pipe touchpoints, without the need for lifting. Before their arrival it is necessary to perform a direct visual inspection and/or UT measurement at the touchpoint rather than at some distance away from it.
These new methods allow operators to reduce the costs of performing inspections. However, to mitigate any identified problems, line lifting is still required at touchpoints to perform necessary repairs.
Many pipe lifting methods have been developed or simply implemented that are unsafe, costly, or impractical, in many instances compelling operators to rely on them only in critical situations such as when there is a loss of containment.
This paper discusses the conventional methods of line lifting, their benefits and shortcomings for various pipe sizes and layouts and introduces recommended engineering and safety requirements that support a proactive approach to addressing Corrosion Under Pipe Supports.
Petrochemical facilities and refineries consist of many miles of above ground piping that transports product between processing and storage units. These pipes are either supported at ground level or in multi-story pipe racks on varying types and sizes of supporting structures. A common problem these structures create is corrosion and erosion at the junction between the pipe and the support, which reduces the remaining wall thickness of the pipe and compromises the integrity of the entire system.
Inspection techniques such as EMAT and Guided Wave Ultrasonics allow owners to safely inspect and provide qualitative information about the condition of these touchpoints while the lines are on-stream and without the need for lifting.
This has many benefits, including reducing costs and associated risks of performing inspections which traditionally required the lines to be lifted. Operators also have a better understanding of the high-risk areas that require further inspection or repair.