Experimental investigation of spiral seam induction bends

The three kinds of dimensions that is φ325mm×8mm, φ426mm×8mm and φ711mm×10.3mm X52 spiral seam induction bends were manufactured via the induction bending process. Based on that, the property and structure of spiral seam induction bends were investigated. According to the processing technic and design feature of spiral seam bend, the destructive test sampling plan of spiral seam induction bend was proposed. Through the mechanical property tests and design proof test, the spiral seam induction bend was studied and evaluated. The tension and impact tests results show that the strength-toughness of spiral seam induction bend can approach the property of mother pipe when the suitable process was adopted. The transverse guided-weld bend tests results show that the root bend samples in several fixed location of φ325mm×8mm bend pipes crack, which indicate that the smaller diameter spiral seam pipe is not fit for the hot bending. The observational check results show that the welding joint misalignment occurs at the inner arc of φ711mm×10.3mm spiral seam induction bend, which indicate that the configuration of spiral seam induction bend is easy to be affected during bending process with the decrease of thicknessto-radius ration of pipe. The design proof test of φ426mm×8mm bend pipe shows that the spiral seam induction bend does not rupture at the computed proof test pressure.