TST157 is an AS568-157 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 4.487 in (113.97 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 4.693 in (119.2 mm). In service, this back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
The material holds up against strong acids and bases, oxidizing media, and steam. That behavior comes from the compound itself: PTFE (Teflon) is known for non-stick, non-contaminating surface characteristics and excellent dielectric properties. Continuous operating temperature is published at -65°F (-53.9°C) to 500°F (260°C). Applications involving service requiring elastic recovery or molten alkali metals call for a different compound.
Common environments for this compound include aggressive-media pipelines, pharmaceutical and biotech, and laboratory equipment.
TST157 ships individually. As always, verify media compatibility and operating conditions against the requirements of your specific application. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.
description 2103-157 PTFE S/T BUP FDA
Actual_CS 0.103 inch (2.62 mm)
Actual_ID 4.487 inch (113.97 mm)
Actual_OD 4.693 inch (119.2 mm)
ProductCode Description O-Rings - Backup Rings