Testing of Coal Tar Coatings (II)—Field Exposure in Cold Climates

Details of an experiment are given in which 10-foot lengths of pipe were buried in Canada at depths of 1 through 5 feet after application of five systems of coatings and wrappings on groups of 5 pipes each. Pipes were buried after testing with an electronic holiday detector with self-registering thermometers in two pipes at each level. After a year’s exposure the pipes were unearthed and tested electrically for holidays. Only a limited number of holidays were found and they were not apparently related in any way to the kind of coating or severity of exposure. Temperatures registered ranged from 25 F to 34 F. increasing with depth. Another test of pipes exposed to atmosphere but protected from the elements was made. Results after a year showed that although temperatures of —8 F had been reached, holidays were few except in sections unwrapped but coated with unplasticized enamel. The advantages of wrapping in protecting the coating were obvious. 5.4.5