APG stocks the TST245, an AS568-245 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 4.359 in (110.72 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.637 in (117.78 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
As a material, PTFE (Teflon) is known for one of the lowest coefficients of friction of any solid and non-stick, non-contaminating surface characteristics. Expect good resistance to steam, strong acids and bases, and solvents. Rated temperature range runs from -65°F (-53.9°C) to 500°F (260°C) in continuous service. It is not the right choice where elemental fluorine at temperature or molten alkali metals are present.
You will find this material specified across chemical processing, aggressive-media pipelines, and food and beverage.
TST245 ships individually. As always, verify media compatibility and operating conditions against the requirements of your specific application.
Description *2103-245 PTFE S/T BUP FDA
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 4.359 inch (110.72 mm)
Actual Outside Diameter 4.637 inch (117.78 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings