Testing of coating systems under insulation

Challenge

Corrosion under insulation (CUI) is the number one threat to piping and vessels in the oil and gas industry and represents 50% of reported hydrocarbon leaks. One of the main barriers against CUI is the coating. 

The expected lifetime for the coating barriers exposed to marine environment under insulation is not sufficiently explored or documented. The performance of different product, and their dependency on application quality or type of insulation systems, will vary. Expected lifetimes can range from 2 to 35 years. Coating condition is difficult to assess during operation, and there is a strong need for a proper statistical foundation to ensure that the inspection and maintenance routines are aligned with the expected lifetime of the coating system.

Solution

Benchmark, according to international standards, different coating systems from different suppliers and compare their performance against different insulation materials.

• Test on 24 different spool pieces, each might be split into two i.e. shop prepared (sandblasted and sprayed) and at-site prepared (mechanical cleaning and brushed).
• Perform exposure as per AMPP TM21442-2023 for 6 months.
• Evaluate in-situ EIS (Electrochemical Impedance Spectroscopy) vs. time.
• Evaluate physical coating degradation after exposure.
• Compare results and advise on expected lifetime for the coatings, ref. Table B1 in DNV-RP-G109.
• Deliver a detailed test report including product name and test results to the joint industry project (JIP) participants.
• Implement results into DNV-RP-G109 Risk based management of corrosion under insulation, at a generic coating system level.

Benefits and value

More detailed insight into the expected lifetime of coating barriers will allow maintenance and inspection activities to be more focused on high-risk items.

• Inspection of objects with long expected coating lifetimes can be postponed.
• The design of new assets will utilize the new insight, ensuring the best coating and insulation solutions are identified from a lifetime  perspective.
• Increased safety and decreased cost.

Project details

Project partners

• 5 oil and gas operators enrolled
• More participants wanted.