Plastic Lined High Pressure Rotary Seals

This plastic lined PN 682-5-303 Kalsi Seal is still in excellent condition after running 1,000 hours at 7,500 to 7,800 psi (51.71 to 53.78 MPa) with a surface speed of 252 ft/minute (1.28 m/s).
This plastic lined PN 682-5-303 Kalsi Seal is still in excellent condition after running 1,000 hours at 7,500 to 7,800 psi (51.71 to 53.78 MPa) with a surface speed of 252 ft/minute (1.28 m/s).

Higher Differential Pressure, Lower Breakout Torque

Plastic Lined Enhanced Lubrication Seals have a low friction, high modulus layer of plastic at the dynamic surface, and an elastomer energizing section that forms the seal body. Compression of the elastomer body loads the plastic surface against the shaft. This construction method positions the highly extrusion resistant plastic material at the housing-to-shaft extrusion gap, for increased resistance to high differential pressure. The plastic layer has a lower coefficient of friction than elastomers, which minimizes breakout torque and helps to assure that the seal does not rotate in the seal groove.

As with other Kalsi Seals, plastic lined seals rely on hydrodynamic interfacial lubrication to minimize adhesive wear of the seal and shaft surfaces. The technological breakthrough that makes plastic lined seals possible is the enhanced lubrication wave geometry, which has the required level of hydrodynamic effectiveness to lubricate high modulus plastics in extreme high differential pressure sealing conditions.

Examples of High Pressure Test Results with Plastic Lined Seals

Plastic lined PN 682-5-303 seals were in excellent condition after 1,000 hour duration testing at 7,500 to 7,800 psi (51.71 to 53.78 MPa) in 115 to 130°F (46.11 to 54.44°C) service conditions simulating a 4.875” (123.83mm) washpipe rotating at 200 rpm. They have also performed well in 300 hour duration testing at 3,000 psi (20.68 MPa) with 0.010” (0.25mm) dynamic runout in 200°F service conditions simulating a 10.375” (263.53mm) RCD mandrel rotating at 200 rpm. These tests, which used an ISO 150 viscosity grade lubricant, were conducted with our patent-pending floating backup ring arrangement, with which minimizes clearance at the high pressure extrusion gap. In each test, the extrusion gap defined by the backup ring was designed to be appropriate for the sealing diameter of the targeted application. Successful 4,000 psi tests have been conducted in washpipe service conditions with lubricant viscosities as low as ISO 32 viscosity grade.

Test results suggest that plastic lined seals are appropriate for use as pressure-retaining seals in extreme pressure oilfield applications, such as washpipe assemblies, side entry cement swivels, and RCDs. RCDs will also benefit from the low breakout torque afforded by plastic lined seals. For information on how to implement plastic lined seals with floating backup rings, see the Kalsi Seals Handbook, and call us at 281-240-6500.

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.