Preparation of Pipe Surface For Bitumen Coating During Reconditioning^★

The exterior cleaning of pipe after removal from soil in the preparation for bitumen coating application is a major item of expense during reconditioning. Removal of all adhering material from the metal surface can be accomplished most practically by sandblasting or equivalent treatment. However such procedure is expensive and slow, especially when the line remains intact or in service. Most corrosion products and soil particles are inert in the absence of moisture and the retention of small amounts of such materials on the pipe surface, particularly when adherence is good, will not impair coating effectiveness if moisture is removed. Moisture can be removed by chemical treatment at a reasonable cost, thus reducing cleaning costs without impairing coating results. A solution of diluted pipe primer has been found effective in reducing moisture content of the residual foreign products on the pipe surface.