The primary seat shall be a resilient nylon type locked in a metal seat ring providing bubble tight shutoff. No lubrication shall be required for this seat. The seat shall be maintained in con-tact with the ball by a spring loaded metal seat ring.
A secondary sealing system shall be provided that shall allow injection of a fluid sealant into a sealant groove that shall establish a seal at the stem or seat. Provisions shall be made to prevent damage to the valve due to sealant pressure.