Double-sided spiral submerged arc welded steel pipe with internal and external welding (the fine welding) the process after the first pre-welded --- Our company specializes in the production of thermal expansion of steel pipe, spiral steel pipe, high-frequency welded pipe, the annual distribution of Baotou Steel, Tianjin Steel and other steel mills after wall seamless steel pipe, I plant sided submerged arc welding process in North China's premier technical staff of 35 people, thermal expansion pipe equipment unit is a unit imported from Germany, the error is small, precise scale. Welcome to come to visit and negotiate.