8-317 BLACK FKM 90D BACK-UP RING

The VBU90317 is an AS568-317 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 0.912 in (23.16 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 1.332 in (33.83 mm). This back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Viton® (FKM) delivers the industry benchmark where nitrile reaches its thermal limit and very low compression set at elevated temperature. The compound resists many acids, chlorinated solvents, and aromatic hydrocarbons. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). Applications involving low-molecular-weight organic acids or amines call for a different compound.

Maintenance and OEM teams specify it across oil and gas, chemical processing, and semiconductor equipment.

Reference part number VBU90317 when ordering; the item is sold individually. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.