Background
Scottish Gas Network (SGN) contacted WGM regarding eight LPG storage tanks spread over three sites: Oban, Thurso and Wick. The current coating system was nearing the end of its life, with visible damage present in many areas. They tasked WGM with specifying, applying and inspecting a coating system that would provide their assets corrosion protection for a minimum of 15 years in harsh environments near the coast in northern Scotland.
Coating selection
The existing coating system was a dated four-coat system that required specific climatic conditions with no margin for error. This old system had to be updated due to the coastal location and outdoor nature of the work to be carried out. We found a moisture-cured polyurethane coating system that could be exposed to the elements in around one hour and be applied in temperatures as low as 0°C. It was applied as a two-coat system consisting of a primer followed by a UV-stable topât with the desired colour pigment. The method selected will have a service life in excess of 15 years.
Product data
Products used were selected in consultation with the SGN technical team.
- Stelcatec PR (primer coat)
- Stelcatec TC (topcoat)
Application method
- Grit blast tank surface to remove old coating system
- Create a profile for the coating application
- Inspect blasted steel for cleanliness and to ensure minimum surface profile is achieved
- Stripe coat any welds, flanges or hard-to-reach areas of the tank using a paintbrush
- Spray apply first coat of Stelcatec primer to blasted steel surface and allow to cure
- Inspect the first coat to ensure minimum dry film thicknesses are achieved
- Spray apply second coat of Stelcatec TC to complete coating system, followed by final inspection of coating system
Conclusion
The weather posed a major challenge as you would expect working by the coast. The use of the moisture-cured coating system helped with the smooth running of the project. The thickness of the original coating in certain areas also caused a few challenges but using the experience of our team and a lot of perseverance, we managed to complete the tanks to a very high standard, totally defect-free, much to the delight of our client.
