8-337 BLACK BUNA 90D BACK-UP RING

Part number HB90337 is an AS568-337 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 2.975 in (75.57 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.395 in (86.23 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

The material holds up against water, hydraulic fluids, and greases and lubricants. Buna-N (Nitrile) delivers the most widely specified general-purpose sealing elastomer, strong abrasion and tear resistance. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Exposure to ozone and direct sunlight or ketones will shorten service life.

Maintenance and OEM teams specify it across automotive, fluid power, and construction equipment.

Reference part number HB90337 when ordering; the item is sold individually. Unit weight is approximately 2.6856 g and nominal inside diameter is listed as 3 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.