The TST249 is an AS568-249 white PTFE (Teflon) 55 Shore D Back-Up Ring measuring an inside diameter of 4.859 in (123.42 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 5.137 in (130.48 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
As a material, PTFE (Teflon) is widely chosen for a very wide continuous service temperature range and near-universal chemical inertness. This material stands up to steam, solvents, and nearly all industrial chemicals. Published continuous service range is -65°F (-53.9°C) to 500°F (260°C).
Common environments for this compound include semiconductor fabrication, laboratory equipment, and pharmaceutical and biotech.
TST249 ships individually. Application requirements vary, so validate compatibility with your process conditions prior to installation. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.
Description 2103-249 PTFE S/T BUP FDA
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 4.859 inch (123.42 mm)
Actual Outside Diameter 5.137 inch (130.48 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings