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Header Square ring

Static Seals Square Ring

A Square Ring is a double-acting axial static sealing element, which is a good alternative to the classic O-ring. Due to its square profile, it only gets minimally deformed when put under pressure. This sealing element is very insensitive towards gap extrusion, no Back-up Ring is necessary even at high pressures and it does not twist during installation.

Square Rings are ideal for sealing flanges, valves, plates and fasteners and are available in a variety of common elastomer materials. The most common of these would be NBR, FKM, EPDM, CR, VMQ and FVMQ. Dimensions are available according to AS 568 (inch sizes).  

Square Ring

Fields of application
single acting
double acting
Main use static applications, its design prevents a twisting of the cord
Materials elastomers
  • good alternative to an O-ring 
  • insensitive to gap extrusion
  • additional Back-up ring is rarely required
  • high sealing tightness despite low compression 
  • no twisting during assembly
  • sturdy at high pressures

Main fields of application 

  • axial-static sealing - between flanges, valves, plates and covers 

Operating parameters  
To ensure a reliable sealing function, the operating parameters and their limit values must be checked as a whole. 

Technical values

Pressure up to 50 MPa (from 50 MPa depending on seal gap)
Temperature -30°C / +80°C (material dependent)
Speed -
Pressure up to 50 MPa (from 50 MPa depending on seal gap)
Temperature -20°C / +200°C (material dependent)
Speed -
Pressure up to 50 MPa (from 50 MPa depending on seal gap)
Temperature -40°C / +130°C (material dependent)
Speed -
Maximum values temperature, speed and pressure are simultaneously not applicable! The values vary in dependence of material and media. For technical queries please contact our application consultants – we have the right solution for you. 

Square Ring

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Further to U-ring Type UH
Further to U-ring Type UH
2-EN-Rechteckting Definition

Definition of Square ring dimensions and ordering sizes

  • Inner diameter d1 from approx. 4,42 mm to 456,07 mm
  • Cross section w and height h from approx.  1,68 mm to 5,16 mm

Sealing effect

The sealing effect of the Square ring is the result of the axial or radial compression of the rings cross section when it is installed. Due to its profile and better distribution of the pressure, a high sealing effect is achieved. The system pressure additionally increases the pressure on the sealing surfaces.

Bild 3-Konstruktion

Design information

In general
Square rings are to be installed in rectangular grooves. All edges of the groove must be burr free.

Groove filling 
When compressed, the filling level of the groove with the inserted rectangular ring must not be higher than 80%. For special applications such as vacuum, please contact our application consultants.

Surface quality
In order to achieve an optimum sealing effect, the contact surfaces must meet minimum requirements. The permissible roughness values must be adhered to, especially in pulsating pressure applications.

Mr. Andreas Raidt
Your contact person for

Technology - General sealing topics, special constructions

Mr. Andreas Raidt
Head of Engineering
Do you have any questions, ideas, or suggestions? We are more than happy to assist you with advice. In person, over the phone, or digitally.

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