2103-351 PTFE S/T BUP FDA

Ordered as TST351, this is an AS568-351 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 4.725 in (120.02 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 5.145 in (130.68 mm). The 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 valued for excellent dielectric properties and a very wide continuous service temperature range. Expect good resistance to strong acids and bases, steam, and nearly all industrial chemicals. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C). Verify compatibility before use with elemental fluorine at temperature or molten alkali metals.

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

TST351 ships individually. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.