In-Place Maintenance Painting of Steel Piling.

Several materials and application procedures have been investigated for use in the in-place maintenance painting of steel piling. Coatings designed for application to dry sandblasted piling above the waterline have performed well for two years. Coatings designed for application between tides, so that they are wetted with seawater almost immediately after application, or for application underwater, have performed well for one year. Application above water was accomplished by conventional spraying. Part of the application between tides and a few feet below mean low water was accomplished by a special cofferdam designed for use on steel sheet piling. The rest was accomplished by brushing coatings specially formulated for underwater application. Surface preparation for the latter application was generally by underwater sandblasting, but cleaning with a pneumatic needle gun was also investigated. Laboratory testing indicated that needle gun cleaning was a promising technique.