Square Rings Overview

Square O-ringsA Square Ring is a sealing device made in the form of a torus (round top view), with a square-shaped cross-section (side view).

Other names for Square Rings are Washer Rings, Lathe-Cut Rings, and TetraSeal©.

The primary reason for using a Square Ring in a sealing application is that they perform the sealing function in a superior manner – and at a cost lower than any other comparable sealing device. For existing applications, there is no need to change the design or procedures. Square Rings fit in o-ring grooves and are interchangeable size for size.

Square rings are available in a variety of rubber and plastic materials such as Buna, Viton, EPDM, Teflon, etc. In most static applications, a Square Ring will serve as a direct replacement for an o-ring and generally will perform a high-pressure sealing function as well as or better than an o-ring.

Square Ring Sizes

We primarily stock American Standard (AS568) sizes of square rings in Nitrile and Viton®. We can also supply Square Rings to metric dimensions.

Standard square rings have the same Inside Diameter as the AS568 sizes. However, the Cross-Section dimension is slightly smaller for square rings. The chart above shows the Square Ring cross-sections for the American Standard series sizes.

Square Ring Cross-Sections

Series C/S Inches C/S mm
Zero 0.066 1.67
100 0.099 2.51
200 0.134 3.4
300 0.203 5.16
400 0.266 6.76

Features of Square Rings:

  • Interchangeable with o-rings size for size (Standard AS568A sizes)
  • Uses the same groove as an o-ring
  • Can be used for radial seals
  • Material is homogenous with no joints or laminations
  • Edges accurately formed
  • Extreme close tolerances held on cross-section, ID, and OD
  • Controlled surface smoothness, hardness, elasticity, toxicity, texture
  • The modern, economical option for static applications
  • Available in many compounds

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