9711 standard small caliber seamless ---- my company specializing in the production of thermal expansion pipe, spiral steel pipe, high frequency welded pipe, and annual distribution Baotou Steel, Tianjin Steel and other steel mills in the posterior wall of seamless steel pipe, I plant sided submerged arc welding process in North China's premier, 35 technicians, thermal expansion pipe equipment unit is a German import unit error is small, accurate scale. The public are welcome to visit and negotiate.