Steel piling is preferred for offshore stationary drilling platforms because wood creates a fire hazard and stressed concrete may fail if salt water penetrates to the stressed reinforcement. Methods used by one oil company to protect its platforms are described.
Specific recommendations are made for the three areas into which the platform is divided with respect to corrosion and for tenders and boats used in operations. For the atmospheric zone 10 or more feet above the water line a 6-coat minimum 6-mil vinyl system is recommended. Epoxy and hot spray vinyl systems are under test but not yet evaluated.
In the splash zone, from the water line upward 10 feet, design placing horizontal and diagonal bracing above or below this zone is recommended. Choice of methods of protecting this, the most corrosive zone, depends on the intentions of the company with respect to permanence of the platforms and other factors. Mentioned by the author, with costs per square foot are Gunite, Monel, porcelain enamel, sheet Neoprene, flame-sprayed polyethylene, plastic tapes over vinyl, metalizing, vinyl mastic systems and protective jackets.
Protection of submerged zone areas on fixed and floating surfaces by cathodic protection is recommended. Methods of using magnesium anodes are described. Bonding platform and tender when tender houses welding machine positively grounded to the tender is recommended.
