Ordered as TST121SO, this is an AS568-121 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 1.049 in (26.64 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 1.255 in (31.88 mm). The back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
The material holds up against solvents, oxidizing media, and strong acids and bases. PTFE (Teflon) is specified for non-stick, non-contaminating surface characteristics and near-universal chemical inertness. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C). Verify compatibility before use with elemental fluorine at temperature or molten alkali metals.
Maintenance and OEM teams specify it across food and beverage, aggressive-media pipelines, and chemical processing.
TST121SO ships individually. Nominal inside diameter is listed as 1 1/16 inch. Check the compound against your process media, pressure and temperature before committing to a design. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.
description *121 PTFE SOLID BACKUP RING FDA
Actual_CS 0.103 inch (2.62 mm)
Actual_ID 1.049 inch (26.64 mm)
Actual_OD 1.255 inch (31.88 mm)
ProductCode Description O-Rings - Backup Rings