Square ring

for flange isolating diaphragmsEPDMFKM

Overview
A Square Ring is a double-acting axial static sealing element with a rectangular profile, used as an alternative to classic O-rings for flange and cover interfaces. Its square profile limits deformation under pressure, minimises gap extrusion and prevents twisting during installation.

Materials

• NBR
• FKM
• EPDM
• CR
• VMQ
• FVMQ

Dimensions
Available according to AS 568 (inch sizes). Inner diameter d1 approx. 4.42 mm to 456.07 mm. Cross section (w) and height (h) approx. 1.68 mm to 5.16 mm.

Fields of application

• Axial-static sealing between flanges, valves, plates and covers
• Sealing of fasteners and similar static interfaces

Main use
Designed for static applications; profile prevents cord twisting and ensures reliable axial sealing.

Advantages

• Alternative to standard O-rings for static joints
• Insensitive to gap extrusion
• Additional back-up ring generally not required at high pressure
• High sealing tightness despite low compression
• No twisting during assembly
• Performs reliably at elevated pressures

Sealing effect
Sealing is obtained by axial or radial compression of the ring cross section. The rectangular profile provides improved pressure distribution and increased contact pressure with system pressure.

Design information

• Install square rings in rectangular grooves; ensure all groove edges are burr-free.
• When compressed, groove filling with the inserted ring must not exceed 80%.
• Contact surface quality must meet minimum roughness requirements, especially under pulsating pressure.

Operating parameters
Maximum temperature, speed and pressure values are not simultaneously applicable and depend on material and media. Check operating parameters and limits as a whole.

Technical values by material (indicative)

• NBR: Pressure up to 50 MPa (depending on seal gap); Temperature range -30°C to +80°C; Speed: not applicable
• FKM: Pressure up to 50 MPa (depending on seal gap); Temperature range -20°C to +200°C; Speed: not applicable
• EPDM: Pressure up to 50 MPa (depending on seal gap); Temperature range -40°C to +130°C; Speed: not applicable

caractéristiques / spécifications techniques

• Product type: Square Ring (rectangular-profile static seal)
• Materials: common elastomers (NBR, FKM, EPDM, CR, VMQ, FVMQ)
• Inner diameter (d1): approx. 4.42 mm – 456.07 mm
• Cross section (w) and height (h): approx. 1.68 mm – 5.16 mm
• Sizing standard: AS 568 (inch sizes)
• Pressure capability: up to 50 MPa (material and seal gap dependent)
• Temperature ranges (material dependent): NBR -30°C / +80°C; FKM -20°C / +200°C; EPDM -40°C / +130°C
• Installation: rectangular groove, burr-free edges; groove filling must not exceed 80% when compressed
• Sealing behavior: axial/radial compression; high sealing effect with improved pressure distribution