Case Studies - Long-Term Performance of Passive Fire Protection

Passive fire protection (PFP) coatings are widely used in the onshore and offshore petrochemical industry. The Piper Alpha disaster in 1988 and the Associated Octel incident in 1995 brought home to many the severity of the fires which the PFP may have to resist. The subsequent inquiries recommended that more attention be given to the role of PFP and the testing of its performance. PFP coatings are relied on to provide front-line protection to safety critical components such as structural steel, walls and sometimes vessels, piping and valves. Most importantly, the performance of the PFP coating should not deteriorate over its intended lifetime, which is likely to be the lifetime of the facility itself.

Shell UK Exploration and Production began a project in the early eighties to study the long-term durability of PFP coatings both in terms of their fire performance and their reliability in preventing corrosion of the metal substrate. Samples provided by all the leading manufacturers were exposed to weathering at a maritime test facility. Regular monitoring of the samples, including fire testing in a furnace, revealed some reassuring results. However, new products coming on the market and more severe fire resistance requirements involving jet fire testing have meant that an extension to the study has been necessary. HSE asked HSL to carry out this work.

The further study has involved the contemporaneous weathering of samples of all the commonly used PFP products in an environment similar to that experienced offshore in the North Sea and the extreme conditions occasionally experienced at onshore coastal and estuarine petrochemical sites. Regular destructive testing makes it necessary for a large number of samples to be weathered over a long timescale (at least 10 years). It is also essential to establish a 'baseline' performance on new products against which any deterioration can be measured. Samples were periodically removed to determine the degree of corrosion and measure their fire performance in standard fire tests: the hydrogen furnace fire resistance test (BS476 : Part 20 : Appendix D) and the jet fire resistance test (currently out for public comment as a draft British Standard). As with the earlier study by Shell, the results generally give confidence in the products. However, proper application and maintenance of PFP coatings is critically important.

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