Manufacture Difficulties Concerning Small-sized High-D/S Spiral Welded Pipe and Related Countermeasures

Analyzed here in the paper are the difficulties as encountered with forming and welding processes during manufacture of the Φ219 mm×8 mm(Q235B) small-sized, hi-D/S spiral welded pipe, including misalignment, weld peaking, crack and insufficient space for mounting internal welding tools as well as hard controlling of the apparent morphology of the weld.Accordingly relevant countermeasures are also proposed.The analysis suggests that the misalignment occurrence can be reduced by shortening the distance between the first roller at the front section of the arm and the feeding side to 60~110 mm, increasing the center distance between Beam 1 and Beam 3, and properly setting the screw down value of Beam 2;the weld peaking can be reduced by optimizing the forming angle range as to 46°~60°, the taper angle of the vertical roll surface as 2°~3°, and increasing the height of the lateral side of each bearing roller;and that cracks can be minimized by reducing the residual stress, the forward resistance and the extrusion thickness at the steel strip edge during the forming process of the steel pipe.