Product Description
John Crane — one of the largest and most widely specified suppliers of industrial packing and sealing materials in the twentieth-century United States — marketed asbestos-containing packing not only as bulk continuous braided coil but also as pre-formed, die-molded packing seal cartridges: complete ring sets sized and shaped for direct drop-in installation into a specific pump or valve stuffing box, sold as a kit rather than cut from bulk.
The pre-formed cartridge approach was intended to simplify maintenance: instead of requiring a mechanic to measure, cut, skive, and stagger a set of packing rings from continuous braided rope, the John Crane cartridge shipped as a complete ring set — typically five or six rings plus a lantern ring — dimensioned to the stuffing-box bore and shaft diameter of the target equipment. These cartridges were widely used in refinery pump service, chemical-plant pump and valve service, power-plant boiler-feed and condensate pumps, U.S. Navy shipboard pump and valve stuffing boxes, and general industrial process equipment.
Plaintiffs alleged in publicly filed U.S. asbestos personal-injury and wrongful-death litigation that John Crane pre-formed packing seal cartridges were manufactured through the asbestos era with braided asbestos yarn (primarily chrysotile) as the primary structural fiber, often impregnated with graphite, PTFE, or other lubricants to reduce friction against the rotating shaft or reciprocating valve stem.
Workers Exposed
Millwrights, industrial maintenance mechanics, and Navy machinist mates who repacked pump and valve stuffing boxes with John Crane cartridge sets allegedly disturbed asbestos fibers at each maintenance cycle. Even though the cartridge simplified installation, the maintenance workflow still exposed workers: the old, heat-hardened cartridge rings had to be dug out of the stuffing box with picks and hooks — an activity that plaintiffs alleged released significant fiber quantities as the deteriorated rings crumbled. The stuffing box then had to be cleaned. The new cartridge rings had to be seated with a tamping tool, and any adjustment cuts (to accommodate stuffing-box depth or lantern-ring position) exposed the fresh asbestos yarn. Refinery operators, power-plant mechanics, and pipefitters performed the same repacking task on their assigned equipment on scheduled preventive-maintenance cycles. Navy machinist mates repacked pump and valve stuffing boxes throughout shipboard engineering spaces as underway maintenance.