Stem Design
The stem is of integral forged design .The minimum diameter of the stem shall per the standard requirement .The connection of the stem and disc is T type .The strength of the connecting area is bigger than that of the T threaded part of the stem .The strength test if that area conforms to API 591.
Stem Nut
Usually,the stem nut is made of ASTM A439 D2.It is also can be made of copper ally if being requested by the customer .For large sized gate valves (NPS 10 for Class 150,NPS 8 for Class 300,NPS 6 for Class 600,NPS 5 for Class 900),rolling bearing is fitted at the two sides of the stem nut in order to minimize the open and close torque of the gate valve.
Special Gate Valve
Besides the common gate valves ,our Company's also makes cryogenic gate valve,Jacketed Gate Valve,Bellow Sealed Gate Valve,Extension Stem Gate Valve for underground application,Flat Gate Valve,etc.