Ordered as TST442, this is an AS568-442 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 7.225 in (183.52 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 7.775 in (197.49 mm). The back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
This material stands up to steam, nearly all industrial chemicals, and strong acids and bases. That behavior comes from the compound itself: PTFE (Teflon) offers non-stick, non-contaminating surface characteristics and excellent dielectric properties. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). It should not be specified for service in elemental fluorine at temperature or service requiring elastic recovery.
Common environments for this compound include laboratory equipment, food and beverage, and chemical processing.
TST442 ships individually. Nominal inside diameter is listed as 7 1/4 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.
description 2103-442 PTFE S/T BUP FDA
Actual_CS 0.275 inch (6.99 mm)
Actual_ID 7.225 inch (183.52 mm)
Actual_OD 7.775 inch (197.49 mm)
ProductCode Description O-Rings - Backup Rings