The TST261 is an AS568-261 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 6.734 in (171.04 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 7.012 in (178.1 mm). This back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.
As a material, PTFE (Teflon) is known for a very wide continuous service temperature range and non-stick, non-contaminating surface characteristics. The compound resists solvents, steam, and oxidizing media. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C).
You will find this material specified across aggressive-media pipelines, food and beverage, and pharmaceutical and biotech.
Stocked as TST261 and sold individually. Check the compound against your process media, pressure and temperature before committing to a design.
Description 2103-261 PTFE S/T BUP FDA
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 6.734 inch (171.04 mm)
Actual Outside Diameter 7.012 inch (178.1 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings