According to the test indicated the relevant US research institutions, large diameter spiral pipe with large-caliber Longitudinal course of a same level, but the
ssaw steel pipe has a high impact toughness.
Large diameter spiral pipe blast occurred as positive weld suffered stress and the resultant stress is relatively small, blasting the mouth is generally not originated in the spiral weld, but whether it is still the yield pressure burst pressure, spiral welded pipe are lower than the straight seam pipe. Large diameter spiral weld pipe is generally degree helix angle, so the spiral weld resultant stress is bursting Longitudinal principal stress test also shows the deformation rate was significantly greater than the spiral steel pipe blasting the mouth ring Longitudinal.
According submerged arc welding process delineated, each weld should have the arc at the place and extinction, but in each Longitudinal welding girth, unable to meet the premise, thereby extinction may have more at multi weld defects. In an interview with the pipe internal pressure, typically produces two main stress on the wall, ie the radial stress and axial stress. Followed by increasing the diameter of the steel pipe, the steel grade improvement, the greater the occurrence of ductile fracture tip steady expansion trend.
Because the transfer line output volume changes, the actual disposal process, the pipe is subject to random alternating load effect. Low cycle of fatigue strength solution pipe for determining life of the pipeline is of great significance. Under the same operating pressure, spiral welded pipe than Longitudinal unified diameter wall thickness can be reduced.
