**2107-321 PTFE SPIRAL B/U FDA

Part number TSP321 is an AS568-321 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 1.162 in (29.51 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 1.582 in (40.18 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

PTFE (Teflon) is specified here for non-stick, non-contaminating surface characteristics and near-universal chemical inertness. The compound resists nearly all industrial chemicals, strong acids and bases, and steam. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). It is not the right choice where service requiring elastic recovery or molten alkali metals are present.

Maintenance and OEM teams specify it across semiconductor fabrication, laboratory equipment, and aggressive-media pipelines.

TSP321 ships individually. Nominal inside diameter is listed as 1 3/16 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.