... simple operation 1.MZ-type semi-automatic submerged arc welding production line widely used on all kinds of steel pipe,round-and ... cone,polgon-highpoles such as the welding seam sheet.2.Using submerger arc welding,surface smooth,non-polluting,non-luminous ... ,open-length welding,weldingspeed 2-3m/min.With high speed welding,less investment and savings ...