Plastic Backup Ring Sizes

Our patented laterally floating metal backup ring technology allows a high-pressure shaft seal to operate for extended periods by providing the smallest practical extrusion gap clearance. The technology is applicable to many different types of equipment, such as side port swivels, hydraulic swivels, rotary control devices, washpipe assemblies, etc.

The metal backup rings can float laterally to follow shaft runout because they are axially force balanced. This force balance is caused by the pressure of the seal lubricant acting on equally sized hydraulic areas defined on the ends of the metal ring by face sealing O-rings. These O-rings are susceptible to extrusion-type damage in extreme pressure conditions due to the pressure itself, and due to pressure-induced equipment deformation. The plastic backup rings prevent O-ring extrusion damage by bridging the gap between the metal backup ring and the mating equipment surfaces. This ensures that the O-rings do not become the weak point of the rotary sealing assembly.

The plastic backup rings have a much lower coefficient of friction, compared to O-rings. This facilitates lateral motion of the metal backup ring, and reduces motion-induced wear of the metal backup ring. For additional information on how these technologies can be used to address your high-pressure rotary shaft sealing challenges, contact Kalsi Engineering.

 

Table 1: Plastic backup rings for the outer balancing grooves

Shaft Diameter, Inches Part Number Groove Outer Dia, Inch Groove Radial Width, Inch Groove Axial Depth, Inch Use With This O-ring
2.750 712-3-* 4.507-4.512 0.212-0.222 0.130-0.133 2-243
2.750 712-2-* 4.632-4.637 0.212-0.222 0.130-0.133 2-244
4.500 712-9-* 6.040-6.045 0.212-0.222 0.130-0.133 143mm x 3.5mm
4.500 712-10-* 6.145-6.150 0.212-0.222 0.130-0.133 147mm x 3.5mm
8.434 712-6-* 9.970-9.975 0.212-0.222 0.130-0.133 243mm x 3.5mm
8.434 712-5-* 10.126-10.131 0.212-0.222 0.130-0.133 2-273 or 247mm x 3.5mm

* The complete part number consists of the number given in the table plus the material dash number (-32, -33 or -35).

 

Table 2: Plastic backup rings for the inner balancing groove

Shaft Diameter, Inches Part Number Groove Inner Dia, Inch Groove Radial Width, Inch Groove Axial Depth, Inch Use With This O-ring
2.750 712-1-* 2.953-2.958 0.212-0.222 0.130-0.133 77.5mm x 3.55mm
4.500 712-11-* 4.670-4.675 0.212-0.222 0.130-0.133 2-248 or 121mm x 3.5mm
8.434 712-4-* 8.659-8.664 0.212-0.222 0.130-0.133 2-269 or 222mm x 3.5mm

* The complete part number consists of the number given in the table plus the material dash number (-32, -33 or -35).

 

Updated: June 17, 2017

Kalsi Seals are offered for sale under the terms and conditions of the “Offer of Sale” that is included in the current revision of the Kalsi Seals Handbook.