Leslie Class DLO Control Valve

Product Description

The Leslie Class DLO Control Valve was an industrial control valve manufactured under the Leslie brand, which operated within the corporate umbrella of Keene Corporation. Leslie valves were engineered for demanding industrial environments, including steam systems, process piping, and high-temperature fluid control applications found across heavy manufacturing, power generation, chemical processing, and marine operations. The Class DLO designation identified a specific product line within Leslie’s broader catalog of control and regulating valves intended to manage flow, pressure, and temperature in complex industrial systems.

Keene Corporation, through its various subsidiaries and acquired brands, supplied a wide range of industrial and construction products throughout the mid-twentieth century. The Leslie valve line was among the engineered mechanical products Keene brought to industrial markets, where control valves of this type were installed in boiler rooms, engine rooms, refineries, paper mills, and similar high-heat, high-pressure environments. These settings placed the valves in close proximity to insulated piping, steam distribution systems, and other assemblies that historically incorporated asbestos-containing materials.

Control valves such as the Class DLO were designed to operate within steam and process piping networks for extended service lives, meaning they were regularly maintained, repacked, and inspected over the course of decades. This maintenance cycle brought workers into repeated contact with the valve components and the surrounding insulation systems throughout the product’s operational lifespan.

Asbestos Content

The specific asbestos content of the Leslie Class DLO Control Valve itself is addressed in litigation records, where plaintiffs alleged that the valve incorporated asbestos-containing internal components, including packing materials and gaskets. Valve packing—the compressible material used to prevent fluid leakage around valve stems—was commonly manufactured with asbestos fiber during the periods when Leslie valves were in widespread industrial use. Asbestos was favored for this application because of its resistance to heat, steam, and chemical degradation, making it well-suited to the high-temperature, high-pressure conditions in which Class DLO valves operated.

In addition to the valve’s own components, litigation records document allegations that the Leslie Class DLO Control Valve was routinely installed in systems surrounded by asbestos pipe insulation, asbestos-containing refractory materials, and spray-applied asbestos fireproofing—all product categories associated with Keene Corporation’s broader industrial supply activities. Plaintiffs alleged that work on or near the valve necessarily involved disturbing these surrounding materials, compounding exposure beyond the valve components themselves.

Keene Corporation’s involvement in multiple asbestos-containing product lines across categories including floor tile, pipe insulation, refractory, and spray fireproofing is documented in litigation and regulatory records, establishing a pattern of asbestos use across the company’s product portfolio during the relevant era.

How Workers Were Exposed

Industrial workers in a range of trades and facilities encountered the Leslie Class DLO Control Valve in the course of routine work. Because the product was designed for installation within steam and process systems, exposure opportunities arose at multiple points in the valve’s lifecycle: during initial installation, during routine maintenance and repacking operations, and during system modifications or decommissioning.

Installation: Workers installing Class DLO valves in boiler rooms, plant utility systems, and process piping networks worked alongside pipefitters and insulators who applied asbestos-containing pipe coverings to adjacent runs of pipe. The cutting, fitting, and finishing of asbestos insulation in close quarters generated airborne fiber that affected all trades present in the work area.

Valve Repacking and Maintenance: Valve packing deteriorates over time under steam and pressure, requiring periodic replacement. Litigation records document allegations that removing worn asbestos packing material from valve stems and installing new packing was a routine maintenance task performed by mechanics, pipefitters, and millwrights throughout the operational life of these valves. Scraping, cutting, and handling degraded packing material can release respirable asbestos fibers. Workers performing this task in confined mechanical spaces—engine rooms, boiler rooms, below-deck compartments, and similar environments—faced conditions that limited ventilation and increased fiber concentration.

Surrounding System Work: The environments where Class DLO valves were installed—power plants, industrial facilities, marine vessels, and refineries—were extensively insulated with asbestos-containing pipe covering, block insulation, and refractory materials. Any maintenance or repair activity in these spaces, even work not directly involving the valve itself, could disturb surrounding asbestos insulation and generate exposure for workers in the area.

Bystander Exposure: Industrial workers generally, including those not directly handling the valve or its packing, were potentially exposed when maintenance activities in shared workspaces generated airborne asbestos fiber. In large boiler rooms and mechanical spaces, this bystander exposure affected workers across multiple trades simultaneously.

Plaintiffs in litigation involving Leslie valves and Keene Corporation products have alleged that neither adequate warnings about asbestos hazards were provided nor were appropriate protective measures communicated to workers using or maintaining these products.