243 PTFE SOLID BACKUP RING FDA

Ordered as TST243SO, this is an AS568-243 white PTFE (Teflon) 55 Shore D Back-Up Ring supplied with an inside diameter of 4.109 in (104.37 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.387 in (111.43 mm). The back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

The compound resists steam, oxidizing media, and solvents. That behavior comes from the compound itself: PTFE (Teflon) delivers one of the lowest coefficients of friction of any solid and excellent dielectric properties. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). It should not be specified for service in elemental fluorine at temperature or service requiring elastic recovery.

Maintenance and OEM teams specify it across food and beverage, laboratory equipment, and chemical processing.

TST243SO ships individually. Nominal inside diameter is listed as 4 1/8 inch. Review your operating media and conditions against this specification before installation. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.