This type of gate valve design is common for fuel safety shutoff in industrial burner applications (boilers, furnaces, flares, etc). If the seats are constructed of the proper materials, they can be rated to Class VI seat leakage.
The most common valve I'm aware of in this design configuration...
Another possibility for safety shut off valves is MAXON which offers FMEDA reports by exida, a third party independent tester, for SIL3 capable valves to be used for FCI Class VI seat leakage. These are mostly fuel shut off valves for boilers and furnaces.
See here...
From what I know of Maxon valves, they're specially designed for fuel safety shut off. Ball valves (Jamesbury, VCI, Fisher) require regular maintenance to tighten their packings otherwise you end up with fuel leaks. Maxon valves have all metal seats with no packings or elastomers. Ball valves...
