Ordered as TST317SO, this is an AS568-317 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 0.912 in (23.16 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 1.332 in (33.83 mm). The back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.
PTFE (Teflon) is specified here for one of the lowest coefficients of friction of any solid and very wide continuous service temperature range. The compound resists strong acids and bases, nearly all industrial chemicals, and steam. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C). Applications involving molten alkali metals or elemental fluorine at temperature call for a different compound.
You will find this material specified across aggressive-media pipelines, food and beverage, and chemical processing.
Order part number TST317SO, sold individually. Application requirements vary, so validate compatibility with your process conditions prior to installation. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.
Description 317 PTFE SOLID BACKUP RING FDA
Actual Cross Section 0.21 inch (5.33 mm)
Actual Inside Diameter 0.912 inch (23.16 mm)
Actual Outside Diameter 1.332 inch (33.83 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings