1995 · 29 citations · 0 references
In 1984, the Hutton TLP was installed with a sealed thermal-sprayed aluminum (TSA) coating. After eight years of service, the TSA coating on the production risers and tethers was still in good condition. The condition in the splash zone was indistinguishable from other inspected components. However, there were notable differences between the production risers and the tethers. The tethers, having a vinyl sealer, showed a blistered surface, while the risers, with a silicone sealer, did not show any blistering. No corrosion has been observed underneath any of the blisters. The importance of adequate sealers in connection with blistering has been documented by testing. The excellent performance of TSA coating in the splash zone is further documented by field studies published in the last few years. Initial confidence in the splash-zone performance of the thermal-sprayed aluminum (TSA) coating for the Hutton TLP was based on results of in-house salt fog tests, the experience of the American Welding Society (AWS) and the US Navy, and information from the British Standard Institution.1-3 The AWS study evaluated various parameters such as coating thickness, surface preparation, and sealer coatings in long term exposures in several environments. Sealed TSA-coated panels (80 microns) at Wrightsville Beach, North Carolina, showed no damage to the underlying steel after 19 years exposure.1 The main result from the US Navy study was the successful performance of a 125 micron unsealed TSA coating after a 15-year exposure and a 100 micron TSA coating after 18-1/2 years (Port Hueneme Harbor, California).2