221 PTFE SOLID BACKUP RING FDA

APG stocks the TST221SO, an AS568-221 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 1.421 in (36.09 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 1.699 in (43.15 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The material holds up against nearly all industrial chemicals, oxidizing media, and strong acids and bases. That behavior comes from the compound itself: PTFE (Teflon) is widely chosen for near-universal chemical inertness and non-stick, non-contaminating surface characteristics. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). It should not be specified for service in molten alkali metals or service requiring elastic recovery.

You will find this material specified across semiconductor fabrication, food and beverage, and aggressive-media pipelines.

Reference part number TST221SO when ordering; the item is sold individually. Nominal inside diameter is listed as 1 7/16 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.