Key Specifications / Parameters Part Number: 21B9340X012 Product Type: Anti‑extrusion ring / backup ring Material: Carbon‑filled PEEK (or similar high‑performance polymer) for elevated temperature/pressure service Application: Prevents extrusion of sealing material (e.g., PTFE seal or soft seat) in the valve trim stack under high differential pressure/temperature service Typical Fitment: Included in parts tables for Fisher ET/EAT valves (e.g., NPS 2 size in some “above 232 °C / 450 °F” service) Service Conditions: Intended for elevated temperature and pressure service where standard backup rings would not suffice Role in Assembly: Positioned just beneath the seal ring (or adjacent to packing) so that when the seal attempts to extrude into a gap, the anti‑extrusion ring blocks that path and maintains seal integrity
