Internal Stress Analysis of ihe Welds Seam in Long Distance Pipeline

Internal stress of welds seam for long distance pipeline is analyzed starting with any point of circumferential stress on pipe wall. The internal stress is consisting of circumferential stress and axial stress, from which the compound stress of the weld seam is derived. Through comparing stresses oh longitudinal seam, and circumferential seam, it is concluded, that the longitudinal seftm has highest pressure-bearing capacity, the circumferential seam lowest, while the spiral seam goes in between the two. It is considered that the explosion origin generally is not located at the spiral seam if explosion occures in the pipelines with same diameters, same wall thickness, and also same pressure as in longitudinal welded pipe. As a result, the safety of the spiral welded pipe is helieved higher than longitudinal welded pipe. The calculations show that wall thickness can be reduced accordingly if the spiral welded pipe is used in the same case said above, and the capital can be saved to increase economical benefits.