The valve body and bonnet are fully welded and sealed, with the advantage of no external leakage. The third type is the pressure self-tightening bonnet forged steel gate valve. Valves designed with this connection type feature a threaded connection between the valve body and bonnet, with an internal pressure self-sealing ring for sealing. The advantage is that the higher the internal pressure, the better the sealing performance. You can reasonably select our valves based on your actual situation.