The TST106SO is an AS568-106 white PTFE (Teflon) 55 Shore D Back-Up Ring built to an inside diameter of 0.174 in (4.42 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 0.38 in (9.65 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
The material holds up against oxidizing media, solvents, and steam. That behavior comes from the compound itself: PTFE (Teflon) is valued for non-stick, non-contaminating surface characteristics and a very wide continuous service temperature range. Rated temperature range runs from -65°F (-53.9°C) to 500°F (260°C) in continuous service. It should not be specified for service in service requiring elastic recovery or molten alkali metals.
Maintenance and OEM teams specify it across pharmaceutical and biotech, semiconductor fabrication, and laboratory equipment.
Order part number TST106SO, sold individually. Nominal inside diameter is listed as 3/16 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.
Description *106 PTFE SOLID BACKUP RING FDA
Actual Cross Section 0.103 inch (2.62 mm)
Actual Inside Diameter 0.174 inch (4.42 mm)
Actual Outside Diameter 0.38 inch (9.65 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings