This back-up ring is supplied in AS568-338 white PTFE (Teflon) 55 Shore D supplied with an inside diameter of 3.1 in (78.74 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.52 in (89.41 mm), catalogued under part number TST338SO. It extends o-ring service life by supporting the seal against extrusion under high pressure.
PTFE (Teflon) is specified here for excellent dielectric properties and one of the lowest coefficients of friction of any solid. Expect good resistance to strong acids and bases, nearly all industrial chemicals, and solvents. The material carries a published service range of -65°F (-53.9°C) to 500°F (260°C).
It sees regular use in chemical processing, laboratory equipment, and pharmaceutical and biotech.
TST338SO ships individually. Nominal inside diameter is listed as 3 1/8 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.
Description 338 PTFE SOLID BACKUP RING FDA
Actual Cross Section 0.21 inch (5.33 mm)
Actual Inside Diameter 3.1 inch (78.74 mm)
Actual Outside Diameter 3.52 inch (89.41 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings