Part number TST235SO is an AS568-235 white PTFE (Teflon) 55 Shore D Back-Up Ring built to an inside diameter of 3.109 in (78.97 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 3.387 in (86.03 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
PTFE (Teflon) delivers near-universal chemical inertness and non-stick, non-contaminating surface characteristics. Expect good resistance to strong acids and bases, oxidizing media, and nearly all industrial chemicals. Continuous operating temperature is published at -65°F (-53.9°C) to 500°F (260°C). It should not be specified for service in molten alkali metals or service requiring elastic recovery.
Maintenance and OEM teams specify it across pharmaceutical and biotech, chemical processing, and aggressive-media pipelines.
This item is sold individually under part number TST235SO. Nominal inside diameter is listed as 3 1/8 inch. 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 235 PTFE SOLID BACKUP RING FDA
Actual_CS 0.139 inch (3.53 mm)
Actual_ID 3.109 inch (78.97 mm)
Actual_OD 3.387 inch (86.03 mm)
ProductCode Description O-Rings - Backup Rings