424 PTFE SOLID BACKUP RING FDA

TST424SO is an AS568-424 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 4.35 in (110.49 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 4.9 in (124.46 mm). In service, this back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

PTFE (Teflon) is specified here for non-stick, non-contaminating surface characteristics and near-universal chemical inertness. Expect good resistance to strong acids and bases, nearly all industrial chemicals, and steam. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C). Verify compatibility before use with service requiring elastic recovery or molten alkali metals.

Common environments for this compound include chemical processing, semiconductor fabrication, and aggressive-media pipelines.

Stocked as TST424SO and sold individually. Nominal inside diameter is listed as 4 3/8 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.