A 5,000 psi Rotary Test of High Pressure Oil Seals
Our inaugural test of first-generation floating metal backup rings was a 40-day, 5,000 psi test on a 2.75” shaft that was rotated at 350 rpm (252 sfpm) with 0.010” runout, FIM. During the test, the ISO 320 viscosity grade seal lubricant was maintained at 120 to 130°F by under-sleeve coolant circulation. The all-elastomer PN 655-4-114 Extra Wide Enhanced Lubrication Seals were in still in good condition at the end of the test and were capable of continuing operation. This is truly extraordinary performance for high pressure oil seals.
Several factors produced this extraordinary breakthrough in high pressure seal design. First, the floating backup rings produced the smallest practicable extrusion gap clearance, which means the rotary seals were exceptionally well-supported. Second, the rotary seals had dual durometer construction, placing an extrusion-resistant 95 Durometer Shore A seal material against the extrusion gap. Third, compared to non-hydrodynamic seals, the hydrodynamic activity of the enhanced lubrication waves allowed the rotary seals to run relatively cool, which helped to reduce temperature related modulus loss of the seal material that was located at the extrusion gap. Fourth, the hydrodynamic lubrication activity minimized the negative aspects of having a very wide dynamic sealing lip, and the additional lip width improved high pressure extrusion resistance by reducing pressure-induced stress.
Since this inaugural test, our engineers have gone on to develop even more extrusion resistant high pressure rotary seals, and to develop several improvements to our floating metal backup ring technology. The backup ring improvements simplify assembly, provide increased dimensional stability in large diameters, reduce journal bearing loads, accommodate significantly more runout, and increase overall pressure capacity. This innovative fluid sealing solution has applicability to a wide range of rotary shaft seal assemblies, such as high-pressure hydraulic swivels, rotating control devices (RCDs), washpipe assemblies, and oilfield well cementing heads. Contact our engineering staff for more information.