1.Bow-out proof stem

For the purpose of preventing the stem from flying off  resulting in abnormal rising of the inner pressure of valve,shoulder is fixed at the lower part of the stem.In addition,in order to prevent leakage resulting from burnout of packing set of the stem in a fire,thrust bearing is set at the contact position of the shoulder at lower part of the stem and valve body.Thus an inverse seal seat is formed which will prevent leakage and avoid accident.

2.Free leakage of body Sealed construction

The connective position of valve body and bonnet is double sealed by gasket and O-ring,on this base,such factors as fire,high temperature,shock and uneven opening or closing of the torque all can't induce external leakage.

3.Automatic body cavity relief

When the body pressure going up un-normally as the unstable factor,the trunnion ball valve downstream seat will be pushed by un-normally pressure,and the release theunnormal pressure automatically,it doesn't damage to the sealing of upstream seat.