Techniques of Field External Coating for Welded Joints of Pipelines

Field external coating for welded joints of pipeline, a critical link in corrosion control engineering, has a direct influence on the quality of corrosion control. The common existing techniques of field coating for welded joints include asphalt coating, asphalt tape coating, polyethylene tape coating, expoxy powder coating, polyethylene heat fusion sleeve, radiation crosslinked polyethylene heat shrinkable sleeve, compound structure, etc. Described for each technique are its scope of application, advantages and disadvantages, as well as its applicating situations both in China and abroad. It is pointed out that proper selection of the techniques is of importance, and that the following factors shall be considered in the application of coating techniques : ①Proper selection of coating materials; ②Reasonable regulation and execution required by the applica tion technology; ③Quality control and inspection in all process and directions.