Riley Stoker Stoker-Fired and Pulverized Coal Boilers

Riley Stoker Corporation manufactured stoker-fired and pulverized coal boilers that were installed in power generation facilities, industrial plants, and large commercial buildings throughout much of the twentieth century. Workers who operated, maintained, or performed service work on these boilers—or who worked in proximity to them—may have been exposed to asbestos-containing materials incorporated into the equipment and its surrounding insulation systems. Litigation records document that plaintiffs have brought claims against Riley Stoker asserting asbestos-related disease following occupational exposure connected to these products.

Product Description

Riley Stoker Corporation, headquartered in Worcester, Massachusetts, was a leading American manufacturer of steam-generating equipment for industrial and utility applications. The company produced two principal categories of coal-burning boilers: stoker-fired units, which fed solid coal mechanically onto a grate for combustion, and pulverized coal boilers, which ground coal into a fine powder before burning it in suspension within a furnace chamber. Both designs were engineered to generate large volumes of high-pressure steam for driving turbines, heating industrial processes, or supplying building heat.

These boiler systems were large, complex assemblies that included furnace walls, superheaters, economizers, air preheaters, and extensive ductwork. Their scale and operating temperatures—often exceeding several hundred degrees Fahrenheit—made thermal insulation a fundamental engineering requirement. Riley Stoker supplied its boilers to utilities, steel mills, paper mills, chemical plants, shipyards, and municipal facilities across the United States and internationally. Equipment manufactured by the company remained in service for decades, meaning that workers encountered these boilers well into the latter half of the twentieth century, long after the units were originally installed.

Asbestos Content

Litigation records document that Riley Stoker stoker-fired and pulverized coal boilers were associated with asbestos-containing materials in several areas of their construction and installation. Plaintiffs alleged that asbestos was present in or applied to these boiler systems in multiple forms, including:

  • Refractory and insulating cements applied to boiler casings, furnace walls, and high-temperature surfaces
  • Insulating block and pipe covering used on steam lines, headers, and associated piping throughout the boiler room
  • Gaskets and packing used at flanges, handhole covers, manhole covers, and valve connections to maintain pressure seals under high heat
  • Rope and cloth packing used around access doors, expansion joints, and ductwork connections
  • Boiler insulating blankets and sectional block applied directly to exterior surfaces to reduce heat loss

Plaintiffs further alleged that asbestos-containing materials were specified, supplied, or recommended in connection with Riley Stoker equipment either by the manufacturer itself or by insulation contractors working to the manufacturer’s design standards. Whether asbestos materials were factory-applied or field-installed during construction and maintenance, litigation records document that workers present during both installation and subsequent service work were potentially exposed.

How Workers Were Exposed

Industrial workers and tradespeople encountered Riley Stoker boilers across a broad range of job functions. Litigation records document that exposure could occur during initial installation of a boiler system, during routine operation, and most significantly during periodic maintenance, repair, and overhaul cycles.

Boilermakers and construction workers who assembled or installed these units cut, shaped, and applied insulating block, cement, and rope packing to high-temperature surfaces. These activities generated substantial quantities of airborne dust if the materials involved contained asbestos.

Maintenance and repair workers performed tasks that required disturbing existing insulation and gasket materials. Removing and replacing worn gaskets, cracked block insulation, or deteriorated packing required scraping, chipping, and wire-brushing surfaces that had been in service for years. Litigation records document that aged, friable asbestos insulation released fiber concentrations during this type of disturbance.

Pipefitters and plumbers working on steam and condensate lines connected to Riley Stoker boilers cut and fitted pipe covering and applied joint compounds that may have contained asbestos. Their work frequently took place in confined boiler rooms where ventilation was limited and airborne dust could accumulate.

Power plant operators and utility workers who were present in boiler rooms on a continuing basis faced potential bystander exposure even when they were not directly performing insulation work. Deteriorating or damaged insulation on surfaces that remained in service released fibers into the ambient air of the work environment.

Shipyard workers who installed or serviced these boilers aboard vessels faced additional risks due to the enclosed, poorly ventilated nature of ship engine rooms, where dust generated during insulation work had limited means of dispersal.

OSHA standards establishing permissible exposure limits for asbestos were not promulgated until 1971, and earlier regulatory frameworks provided substantially less protection. Workers employed on these boilers before modern regulations took effect had limited means of recognizing or mitigating their exposure.