Abstract
Modern painting practices utilize zinc rich primers to combat corrosion of structural steel. Three different modes of the use of zinc rich primers is discussed; prime and finish in the shop, prime coat only then finish years later, repaint deteriorated and corroded steel years later. The problems experienced and the types of paint systems used are discussed.
The advent of zinc rich primers has promulgated the largest singular advancement in protective coatings for structural steel. Steel Structures of modern construction are mainly protected by the galvanic mechanism offered by the use of zinc rich primers. Most specifications use surface preparation equal to Near White Metal Blast Cleaning SSPC SP-10. This provides a surface completely free of mill scale, rust, and old paint residues. Such a surface also permits intimate contact of the zinc rich primers, which is necessary to achieve galvanic protection.
Coal fired power stations are constructed using at least two units. The largest structure contains the boiler, coal conveyor, water tanks, and considerable equipment. This Structure is 200 to 400 feet high. The structural steel is normally open to the environment. Frequently the second unit is down wind from the first unit, thus, excessive fly ash and coal dust settles on the steel. Only chemical resistant coatings should be used to protect the steel.
