The TST159SO is an AS568-159 white PTFE (Teflon) 55 Shore D Back-Up Ring built to an inside diameter of 4.987 in (126.67 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.193 in (131.9 mm). This back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.
The material holds up against solvents, steam, and nearly all industrial chemicals. That behavior comes from the compound itself: PTFE (Teflon) is known for non-stick, non-contaminating surface characteristics and excellent dielectric properties. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C). It is not the right choice where elemental fluorine at temperature or service requiring elastic recovery are present.
Maintenance and OEM teams specify it across food and beverage, laboratory equipment, and aggressive-media pipelines.
Order part number TST159SO, sold individually. As always, verify media compatibility and operating conditions against the requirements of your specific application.
Description 159 PTFE SOLID BACKUP RING FDA
Actual Cross Section 0.103 inch (2.62 mm)
Actual Inside Diameter 4.987 inch (126.67 mm)
Actual Outside Diameter 5.193 inch (131.9 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings