8-387 BLACK FKM 90D BACK-UP RING

This back-up ring is supplied in AS568-387 black Viton® (FKM) 90 Shore A built to an inside diameter of 17.955 in (456.06 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 18.375 in (466.73 mm), catalogued under part number VBU90387. It extends o-ring service life by supporting the seal against extrusion under high pressure.

Viton® (FKM) is specified here for very low compression set at elevated temperature and industry benchmark where nitrile reaches its thermal limit. The compound resists aromatic hydrocarbons, many acids, and engine and transmission fluids. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C). Exposure to hot water and steam or amines will shorten service life.

It sees regular use in oil and gas, aerospace, and semiconductor equipment.

Stocked as VBU90387 and sold individually. Check the compound against your process media, pressure and temperature before committing to a design. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.