The main risk of seal failure in these applications is due to the numerous problems associated with the secondary dynamic O-ring, potentially resulting in hang-up, fretting or stub sleeve wear. The design of the 8628VSC completely eliminates these common problems.

The 8628VSC is used in tandem with a primary seal such as the 8648VRS. In response to primary seal leakage or in the event of failure, the 8628VSC faces close down to seal the process and direct process flow to flare or drain. This represents a less complex alternative to dual unpressurized seals using an API Plan 52.