Ordered as TST328, this is an AS568-328 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 1.85 in (46.99 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 2.27 in (57.66 mm). The back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
This material stands up to solvents, strong acids and bases, and nearly all industrial chemicals. That behavior comes from the compound itself: PTFE (Teflon) delivers non-stick, non-contaminating surface characteristics and near-universal chemical inertness. Continuous operating temperature is published at -65°F (-53.9°C) to 500°F (260°C).
Common environments for this compound include semiconductor fabrication, aggressive-media pipelines, and pharmaceutical and biotech.
Order part number TST328, sold individually. Nominal inside diameter is listed as 1 7/8 inch. Check the compound against your process media, pressure and temperature before committing to a design. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.
description 2103-328 PTFE S/T BUP FDA
Actual_CS 0.21 inch (5.33 mm)
Actual_ID 1.85 inch (46.99 mm)
Actual_OD 2.27 inch (57.66 mm)
ProductCode Description O-Rings - Backup Rings