Ordered as TST237, this is an AS568-237 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 3.359 in (85.32 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 3.637 in (92.38 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.
As a material, PTFE (Teflon) is specified for non-stick, non-contaminating surface characteristics and near-universal chemical inertness. The material holds up against steam, strong acids and bases, and oxidizing media. Service temperature is rated from -65°F (-53.9°C) through 500°F (260°C). It should not be specified for service in molten alkali metals or service requiring elastic recovery.
Common environments for this compound include food and beverage, aggressive-media pipelines, and chemical processing.
Reference part number TST237 when ordering; the item is sold individually. Nominal inside diameter is listed as 3 3/8 inch. Check the compound against your process media, pressure and temperature before committing to a design.
description 2103-237 PTFE S/T BUP FDA
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 3.359 inch (85.32 mm)
Actual_OD 3.637 inch (92.38 mm)
ProductCode Description O-Rings - Backup Rings