2103-161 PTFE S/T BUP FDA

APG stocks the TST161, an AS568-161 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 5.487 in (139.37 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.693 in (144.6 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.

As a material, PTFE (Teflon) is widely chosen for near-universal chemical inertness and one of the lowest coefficients of friction of any solid. The compound resists solvents, steam, and strong acids and bases. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). Applications involving molten alkali metals or service requiring elastic recovery call for a different compound.

Maintenance and OEM teams specify it across pharmaceutical and biotech, chemical processing, and food and beverage.

This item is sold individually under part number TST161. Nominal inside diameter is listed as 5 1/2 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.