Ordered as TST031, this is an AS568-031 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 1.739 in (44.17 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 1.879 in (47.73 mm). The back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
Expect good resistance to steam, oxidizing media, and solvents. That behavior comes from the compound itself: PTFE (Teflon) is valued for excellent dielectric properties and non-stick, non-contaminating surface characteristics. Rated temperature range runs from -65°F (-53.9°C) to 500°F (260°C) in continuous service.
Maintenance and OEM teams specify it across pharmaceutical and biotech, aggressive-media pipelines, and semiconductor fabrication.
Stocked as TST031 and sold individually. Nominal inside diameter is listed as 1 3/4 inch. Check the compound against your process media, pressure and temperature before committing to a design.
Description 2103-031 PTFE S/T BUP FDA
Actual Cross Section 0.07 inch (1.78 mm)
Actual Inside Diameter 1.739 inch (44.17 mm)
Actual Outside Diameter 1.879 inch (47.73 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings