Feature:
1. Double block and Bleed.
2. Anti-blow-out proof design of stem
3. Stem extensions, suitable for inaccessible areas or buried servies
4. Fire safe: API 607
5. Internal coating and process, usually electroless nickle plating.
6. sealant injection fittings.

Standard:
Pressure & Temp. rating: ASME B16.34
Shell thicknes: ASME B16.34
Face to Face Dimension: ASME B16.10
Flange Connection Dimension:ASME B16.5
Testing and Inspection:API6D