... 4.Self relieving seats, 5.DBB 1,Cast steel ball valves made by our company can be divided ... ball type, trunnion ball type, high, middle and low pressure, high, middle and low temperature, sulphur-resistant and non-sulphur- resistant valve by valve ... military manufacturing technique. 3,Valve teat is so strict that each valve is tested, measured,and ... and provide the considerate service. Steel Ball Valve