Porduct Description: DN350-DN1400 Welded ball valve, adpots trunnion ball piston valve seat struture, better resistance to pipe stress and axial structure of blow-out proof, can replace the stem seal system, two-way double sealing mechanism to ensure the valve can produce both excellent sealing performance under high and low, two-way quad seal tightly ball valve sealing performance more safe and reliable, the valve installed at the bottom of the drain pressure relief hole,to ensure the safe operation of the valve.