Ordered as TST042SO, this is an AS568-042 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 3.239 in (82.27 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 3.379 in (85.83 mm). The back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
PTFE (Teflon) is valued for excellent dielectric properties and a very wide continuous service temperature range. The compound resists nearly all industrial chemicals, oxidizing media, and strong acids and bases. 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, food and beverage, and aggressive-media pipelines.
Order part number TST042SO, sold individually. Nominal inside diameter is listed as 3 1/4 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. For a size or compound outside the standard catalog, APG can quote from a print or sample.
Description 42 PTFE SOLID BACKUP RING FDA
Actual Cross Section 0.07 inch (1.78 mm)
Actual Inside Diameter 3.239 inch (82.27 mm)
Actual Outside Diameter 3.379 inch (85.83 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings