Determining Method of Weld Misalignment of Spiral Submerged Arc Welded Steel Pipes

The appropriate method for determining weld misalignment was given by comparing advantages and disadvantages of all kinds of methods for determining weld misalignment of inside and outside welds of spiral submerged arc welded (SSAW) steel pipes, in order to provide reference for controlling the misalignment during pipe manufacturing, inspection and supervision process. The results show that the common three metallographic determining methods (center line method, arc top offset method and centerline method) used in the actual test all had their advantages and disadvantages, but they all could not accurately reflect the actual weld misalignment of inside and outside welds. The new addition method in API SPEC 5L-2007-ADDENDUM 3 was proposed to be used to determine the weld misalignment. This method not only can accurately reflect the actual weld misalignment, but also have unique weld misalignment determining value, so it can achieve the purpose of controlling the weld misalignment. The X-ray method should only be used as supplementary method for determining weld misalignment because it could not fully guarantee the steel pipe welding quality accord with standard requirement.