Our rotary seal handbook has now been updated to revision level 19. The principal reason for the revision was to update Chapter E4 to show and describe the design of an improved high pressure washpipe assembly for use with Kalsi-brand rotary shaft seals. Compared to the previous design, this improved design provides a much simpler way to incorporate Kalsi Engineering’s patent pending floating backup rings. This is accomplished by eliminating the traditional pressure housing.
These metal backup rings provide the pressure-retaining seals with the smallest possible extrusion gap, which increases pressure capacity and helps to assure long sealing life. The washpipe design is a modular arrangement, where the seals and backup rings are located by a simple stack of housings that is bolted together. This arrangement is robust, economical to manufacture, and much easier to assemble and disassemble, compared to the previous design. The new arrangement reduces the number of precision machined surfaces, and positions the remaining few in locations that are readily accessible during machining and inspection. For example it eliminates the expensive lathe turned threads of the previous arrangement. It also eliminates the use of radial O-rings and the requisite tightly fitting diameters needed for high pressure applications. Overcoming the radial O-ring force during assembly and sufficiently tightening the larger diameter custom threads were the most difficult aspects of assembling the previous design.
Although shown in the context of a high pressure washpipe assembly, the basic stacking housing arrangement is also adaptable to other equipment, such as hydraulic swivels and rotary control devices (RCDs). The chapters that focus on such equipment will be revised to provide detailed design information as time permits.
Handbook revision 19 also includes updates to chapters, A1, B1, C2 to C7, and D5. Many of these chapter revisions include new seal test data. Chapter C4 includes information on the new 673 series Axially Constrained seal, and information on testing of FKM seals.