API 6A gate valve, non-rising stem, rising stem, welded, threade, d, ... colar connection end. casting/forging body. API 6A gate valve: The designs are conformed to the latest API Spec ... the bonnet in order to replace the fill of the valve-stem when the valve bears pressure.The seal surface is ... with preloaded spring, operation torque is little. The wedge valve gate is sealed by wedge seal surface ,it can ...