45 PTFE SOLID BACKUP RING FDA

TST045SO is an AS568-045 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 3.989 in (101.32 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 4.129 in (104.88 mm). In service, this back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Expect good resistance to steam, solvents, and nearly all industrial chemicals. That behavior comes from the compound itself: PTFE (Teflon) delivers a very wide continuous service temperature range and non-stick, non-contaminating surface characteristics. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C).

You will find this material specified across chemical processing, food and beverage, and semiconductor fabrication.

TST045SO ships individually. Nominal inside diameter is listed as 4 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.