John Crane Compressed Asbestos Sheet Gaskets

Product Description

John Crane, Inc. is a global manufacturer of mechanical sealing systems, fluid handling equipment, and related industrial components. For much of the twentieth century, the company produced a broad line of compressed asbestos sheet (CAS) gaskets intended for use in high-temperature, high-pressure industrial environments. These flat sheet gaskets were cut or stamped to fit pipe flanges, valve bodies, pump housings, heat exchangers, pressure vessels, and a wide range of other process equipment found in refineries, chemical plants, power generating stations, marine vessels, and heavy manufacturing facilities.

Compressed asbestos sheet gaskets were considered a standard engineering solution for decades. The material’s ability to withstand extreme heat, resist chemical attack, and maintain a reliable seal under fluctuating pressure made it a preferred choice for engineers and plant operators. John Crane supplied these products under various trade designations and supplied both pre-cut gaskets and large sheets from which maintenance personnel and tradespeople could fabricate custom gaskets on site. The products were distributed widely through industrial supply networks, meaning they appeared in facilities far removed from any direct relationship with the manufacturer.

Production of asbestos-containing gasket materials continued through the mid-1980s, when regulatory pressure and evolving awareness of asbestos hazards prompted the broader industrial sector to develop alternative materials, including compressed fiber sheets using aramid, graphite, and other synthetic compounds.

Asbestos Content

Compressed asbestos sheet gaskets, by definition, rely on asbestos fiber as a primary structural and functional component. The manufacturing process typically combined chrysotile asbestos — and in some formulations amphibole varieties such as amosite or crocidolite — with rubber binders, fillers, and curing agents to produce a dense, flexible sheet material capable of forming tight mechanical seals.

The asbestos fiber content in compressed asbestos sheet gaskets generally ranged from approximately 60 to 85 percent by weight, making these products among the highest asbestos-content industrial materials produced for routine maintenance use. This high fiber loading was intentional: the asbestos network within the compressed sheet provided the thermal stability and compressibility that made the gaskets effective at sealing.

Litigation records document that plaintiffs raised questions about what John Crane knew regarding the hazardous properties of the asbestos fiber incorporated into these products and when the company possessed that information. Internal documents produced during discovery in multiple cases were alleged by plaintiffs to show awareness of asbestos health concerns predating the period when warnings were placed on products or communicated to downstream users and workers.

How Workers Were Exposed

Industrial workers encountered John Crane compressed asbestos sheet gaskets primarily through installation, maintenance, and removal activities. Exposure was not limited to a single trade; rather, the broad industrial distribution of these gaskets meant that pipefitters, millwrights, boilermakers, machinists, refinery operators, power plant maintenance workers, chemical plant personnel, and general industrial mechanics all had documented opportunities for contact with these materials.

Several work tasks were identified in litigation as particularly significant sources of fiber release:

Cutting and fabricating gaskets from sheet stock. When maintenance personnel cut custom gaskets from large compressed asbestos sheets using knives, shears, hole saws, or grinding tools, the cutting action severed the asbestos fiber matrix and released airborne dust. Workers performing these tasks in enclosed shops or tight machinery spaces could be exposed to elevated concentrations of respirable fiber.

Installing new gaskets. Even the act of pressing a pre-cut gasket into a flange face, trimming excess material, or cleaning seating surfaces with abrasive tools could release fibers from the gasket material.

Breaking out old gaskets. Plaintiffs alleged that the removal of deteriorated or heat-fused compressed asbestos gaskets presented severe exposure risks. Gaskets that had been in service under heat and pressure often bonded tightly to metal flange surfaces. Workers used scrapers, wire brushes, grinding wheels, and pneumatic tools to break these gaskets free, generating visible dust clouds that contained respirable asbestos fibers. Litigation records document expert testimony asserting that gasket breakout activities were among the highest-exposure tasks performed by industrial maintenance workers.

Bystander exposure. Workers in adjacent areas of a facility — those not directly handling gasket materials but working nearby during cutting or removal operations — were also identified in litigation as having potential bystander exposure.

The cumulative nature of asbestos-related disease means that workers who regularly handled compressed asbestos sheet gaskets over the course of a career in industrial settings accumulated substantial fiber burdens. Diseases including mesothelioma, lung cancer, asbestosis, and pleural disease have been diagnosed among industrial workers with documented histories of gasket-related asbestos exposure. Mesothelioma, in particular, has been identified in litigation involving John Crane gasket products, given that this malignancy is causally associated with asbestos fiber inhalation and has a latency period commonly spanning several decades.