The Trade That Built America's Boilers — Working Inside the Asbestos

Inside the boiler, where the lagging and refractory lived

Boilermakers built, entered, and rebuilt the boilers and pressure vessels whose hot surfaces were clad in asbestos block lagging and whose fireboxes were lined with asbestos refractory. During new erection the boilermaker worked as the lagging and refractory went on; during outage and repair work he cut, broke out, and removed that dry, friable material to reach the tubes and internals — releasing heavy fiber inside the confined vessel.

Tube work, tear-out, and the outage

The periodic boiler outage — retubing, weld repair, refractory replacement — was the trade's highest-exposure work. Breaking out old asbestos lagging and refractory to access the boiler internals, inside a hot, enclosed vessel with little ventilation, produced some of the highest fiber concentrations any construction trade encountered.

Gaskets and seals

Boiler and pressure-vessel doors, manways, and flanged joints were sealed with asbestos gaskets that the boilermaker cut, fitted, scraped off, and replaced during construction and every repair.

Confined spaces and inadequate ventilation

The inside of a boiler or pressure vessel is the definition of a confined space. Fiber released during lagging and refractory tear-out had nowhere to go, and the boilermaker breathed it for the length of the job.

Respiratory protection came too late

OSHA's first asbestos exposure regulations were promulgated in 1971 — after decades of boilermakers working inside asbestos-lagged vessels. Even after 1971, enforcement was uneven; respirators were available but their use was not consistently required or even encouraged on industrial worksites. Most boilermakers who entered the trade between 1940 and 1975 — now in their 70s and 80s — completed their careers with very little respiratory protection at all.

The occupational-health record

Dr. Irving Selikoff's Mount Sinai research documented elevated mesothelioma incidence across the trades that worked inside and around asbestos-lagged industrial equipment. The disease pipeline, driven by mesothelioma's 20-to-50-year latency between exposure and diagnosis, continues today — the cohort that worked the asbestos-boiler era is being diagnosed now, and will be for the next two decades.

1880 — The founding

The International Brotherhood of Boilermakers was founded on September 1, 1880, in Kansas City, when railroad shop boilermakers organized to standardize wages and working conditions across the steam-locomotive repair shops of the transcontinental rail network. The trade maintains its international headquarters in Kansas City, Kansas.

1900s–1940s — Growth with pressurized steam

The trade grew alongside every American industry that ran on pressurized steam — the electric utility, the petroleum refinery, the chemical plant, the pulp and paper mill, the integrated steel mill, and the shipyard. Boilermakers fabricated, welded, erected, and repaired the pressure vessels that carried the steam — and manufacturers clad those vessels in asbestos block lagging and lined their fireboxes with asbestos refractory.

1940s–1970s — Peak membership and peak exposure

The postwar industrial buildout — the fossil-fired power plants, the expanding refineries, the Navy and merchant fleets — put boilermakers on and inside asbestos-lagged boilers and pressure vessels across the country. The trade's exposure was at its highest concentration during exactly the era now showing the highest mesothelioma incidence rates among retirees.

1970s — Federal recognition

OSHA's 1971 asbestos exposure regulations followed the Mount Sinai cohort studies documenting elevated mesothelioma rates across the industrial trades. Through the 1970s and 1980s, non-asbestos lagging, refractory, and gasket materials replaced the asbestos products in new boiler work.

1980s–today — Post-asbestos era

By the 1980s, asbestos was substantially phased out of boiler lagging, refractory, and gaskets. Boilermakers who entered the trade after that worked under a substantially safer regime — but the disease pipeline from the 1940s-1970s cohort continues, and the outage work of removing legacy asbestos from older boilers extended exposure for some into later decades. The next two decades will continue to draw heavily from the asbestos-era cohort.