Corrosion Under Pipe Supports Is One Of The Leading Causes Of Topside Process Piping Failure. This Is Because Corrosion On These Crucial Pipe Components Is Often Either A Hidden Threat, Undetected By Even The Most Experienced Piping Inspector During Visual Examination, Or It May Be Visible But Cannot Be Quantified.

THE CHALLENGE

The operator identified corrosion affecting 4”, 6” and 10” clamped pipe supports on an offshore platform. Typical inspection solutions available on the market require the complete removal of the clamp component. However, removing these critical features introduces an increased risk of product release and associated health, safety, and environmental consequences. The operator, under time pressure, required an immediate solution that would accurately detect and size corrosion defects without introducing unnecessary risks to the critical system.

THE SOLUTION

After careful assessment, it was determined that the application of ROSEN’s Corrosion Under Pipe Support Inspection Service, utilizing the CIRC tool, would best suit the inspection needs of the operator. ┬áThe CIRC tool utilizes Electro Magnetic Acoustic Transducer (EMAT) technology, a proven sensor technology for the detection and sizing of internal and external corrosion, including pitting.

It was agreed that a partial clamp removal was necessary in order to allow for proper placement of the CIRC frame at the 12 o’clock position of the pipe support. Once in place, the CIRC tool, via control software, is moved axially along the pipe and sends circumferential sound waves around the pipe to inspect the full pipe body for corrosion in one scan. As the tool scans several areas along the pipe, it collects valuable data on the integrity of pipe wall and the pipe support, which are otherwise inaccessible components. The software automatically detects the properties of the anomalies, including position and width, and generates an immediate report for the operator including digital photographs.

In the report from this inspection, one of the anomalies detected along the pipe support showed a length of 230 mm, a width of 18.6 mm, and a remaining wall thickness of 1.04 mm. The percentage of wall thickness loss due to corrosion totaled 83.75%, deeming this defect critical. After independent verification of the findings by the operator, the defect was in fact found to have 81% loss of wall thickness, with a remaining wall thickness of 1.00 mm. The verified data was consistent with the original data collected by the CIRC tool, proving that the EMAT system works with an extremely high level of accuracy.

Additionally, the operator agreed to utilize a newly-developed ROSEN technology, TT-AXUS tool, in future inspections. A key feature of this new development: It is an axially-oriented EMAT device that enables the inspection of the clamped pipe support without the need to partially or fully remove the clamp. This innovation will further ease the integrity management processes for operators.

THE BENEFITS

The CIRC system provided accurate, real-time indications of features present on the asset, without the need to completely remove the clamped pipe supports from the pipe. This enabled the operator to efficiently and safely collect valuable information on the existing corrosion on the critical component of the offshore platform. The project, which was successfully executed, helped to ensure the safe operation of this valuable asset and enabled future integrity management programs.