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568-359 BUNA 70 SQUARE CUT RINGS

Buna-N Square-Cut Ring, 5.725 in ID x 0.21 CS, 70A, Black, -40 to 250°F

Status
Available
Est. Ship Date
24 Oct 2026
Material
Buna-N (Nitrile / NBR)
Dash Size
359
Durometer
70 Shore A
Cross Section Type
Square
Color
Black
Minimum Temperature
-40°F (-40°C)
Maximum Temperature
250°F (121°C)
Nominal Cross Section
3/16 inch
Nominal Inside Diameter
5 3/4 inch
Nominal Outside Diameter
6 1/8 inch
Unit of Measure
EA
SKU:
SH70359
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Product Specification

-
SH70359 is an AS568-359 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring built to an inside diameter of 5.725 in (145.42 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 6.145 in (156.08 mm). In service, this square-cut ring seals with a broad flat contact band instead of the line contact of a round-section ring.

Buna-N (Nitrile) is specified for low compression set under sustained load and the most widely specified general-purpose sealing elastomer. The material holds up against greases and lubricants, petroleum-based oils, and hydraulic fluids. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Applications involving strong acids or polar solvents call for a different compound. The profile itself contributes greater resistance to extrusion than a round section of the same size and simple lathe-cut manufacture at low tooling cost. Note that a square section is less suited to high-speed rotary service, where the larger contact area raises friction and heat.

Common environments for this compound include hydraulic and pneumatic systems, construction equipment, and general industrial maintenance.

Reference part number SH70359 when ordering; the item is sold individually. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.
Item
SH70359
Description
568-359 BUNA 70 SQUARE CUT RINGS
Actual Cross Section
0.21 inch (5.33 mm)
Actual Inside Diameter
5.725 inch (145.42 mm)
Actual Outside Diameter
6.145 inch (156.08 mm)
FDA Compliant
No
Measurement System
Imperial
Metal Detectable
No
NSF Certified
No
Product Code
6017
Product Category
O-Rings - Square/Quad - Commodity