345 PTFE SOLID BACKUP RING FDA

The TST345SO is an AS568-345 white PTFE (Teflon) 55 Shore D Back-Up Ring with an inside diameter of 3.975 in (100.97 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 4.395 in (111.63 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

PTFE (Teflon) is specified here for very wide continuous service temperature range and non-stick, non-contaminating surface characteristics. This material stands up to oxidizing media, nearly all industrial chemicals, and solvents. Rated temperature range runs from -65°F (-53.9°C) to 500°F (260°C) in continuous service.

Maintenance and OEM teams specify it across chemical processing, pharmaceutical and biotech, and food and beverage.

TST345SO ships individually. Nominal inside diameter is listed as 4 inch. Check the compound against your process media, pressure and temperature before committing to a design. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.