Precision machining procedure, controling the gap of stem and extened bonnet below 1mm, guarranting the smooth turning of stem, and  also reduced the possibility of freezing and lossing caused by cryogenic service.

Lip-seal(Elgiloy+PTFE)

The Lip-Seal not only have the flexible compensation function as spring, but also excellent sealing as PTFE. 

Excellent sealing under cryogenic temp. fire safe design as the secondary sealing of graphite.

All the fastners are full threaded construction for cryogenic temp. it is effectively avoid fastners long deformation and sealing failed.