TST021 is an AS568-021 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 0.926 in (23.52 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 1.066 in (27.08 mm). In service, this back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
The material holds up against steam, oxidizing media, and nearly all industrial chemicals. That behavior comes from the compound itself: PTFE (Teflon) is valued for a very wide continuous service temperature range and one of the lowest coefficients of friction of any solid. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C).
Typical settings include food and beverage, semiconductor fabrication, and aggressive-media pipelines.
Order part number TST021, sold individually. 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 2103-021 PTFE S/T BUP FDA
Actual Cross Section 0.07 inch (1.78 mm)
Actual Inside Diameter 0.926 inch (23.52 mm)
Actual Outside Diameter 1.066 inch (27.08 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings