8-157 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90157, an AS568-157 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 4.487 in (113.97 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 4.693 in (119.2 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

As a material, Viton® (FKM) is widely chosen for outstanding high-temperature capability, excellent resistance to compression set and permeation. The compound resists aromatic hydrocarbons, petroleum oils and fuels, and engine and transmission fluids. Published continuous service range is -15°F (-26.1°C) to 400°F (204.4°C). Verify compatibility before use with ketones and esters or hot water and steam.

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

VBU90157 ships individually. Application requirements vary, so validate compatibility with your process conditions prior to installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.