APG stocks the TST279, an AS568-279 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 12.984 in (329.79 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 13.262 in (336.85 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
PTFE (Teflon) is widely chosen for excellent dielectric properties and near-universal chemical inertness. The compound resists nearly all industrial chemicals, oxidizing media, and strong acids and bases. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C).
Common environments for this compound include food and beverage, aggressive-media pipelines, and chemical processing.
Stocked as TST279 and sold individually. Nominal inside diameter is listed as 13 inch. Check the compound against your process media, pressure and temperature before committing to a design. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.
description 2103-279 PTFE S/T BUP FDA
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 12.984 inch (329.79 mm)
Actual_OD 13.262 inch (336.85 mm)
ProductCode Description O-Rings - Backup Rings