A boilermaker is a trained craftsman who produces steel fabrications from plates and sections. The name originated from craftsmen who would fabricate boilers but they may work on projects as diverse as bridges, blast furnaces and the construction of mining equipment.

Many boilermakers are employed in repairing, re-piping and re-tubing commercial steam and hot water boilers used for heating domestic hot water in commercial buildings and multi-family dwellings. Sometimes these boilers are referred to as pressure vessels. Generally, a pressure vessel is a storage tank or vessel that has been designed to operate at pressures above 15 psi (1.03 bar; 103 kPa). The two main tasks of boilermakers involve using oxy-acetylene gas torch sets to cut or gouge steel plate and tubes, followed by gas tungsten arc welding (GTAW), shielded metal arc welding (SMAW), or gas metal arc welding (GMAW) to attach and mend the cut sections of tubes and steel plates.

Boilermaking, welding and fitting tubes can be a full-time year round project at power plants. Since stress fractures, leaks, rust and corrosion cause a continual need for repair or replacement. Power plants often operate at very high steam pressures. Other boilermakers might work seasonally or on an individual project such as re-fitting a boiler in a seagoing vessel or in the one-time remodeling of a steam plant.

What Boilermakers Do

Boilermakers install and maintain boiler systems.

Boilermakers assemble, install, and repair boilers, closed vats and other large vessels or containers that hold liquids and gases.


  • Boilermakers typically do the following:

  • Use blueprints to determine locations, positions, or dimensions of parts

  • Install small premade boilers into buildings and manufacturing facilities

  • Lay out prefabricated parts of larger boilers before assembling them

  • Assemble boiler tanks, often using robotic or automatic welders

  • Test and inspect boiler systems for leaks or defects

  • Clean vats using scrapers, wire brushes and cleaning solvents

  • Replace or repair broken valves, pipes, or joints, using hand and power tools, gas torches and welding equipment

Boilers, tanks and vats are used in many buildings, factories, and ships. Boilers heat water or other fluids under extreme pressure to generate electric power and to provide heat. Large tanks and vats are used to process and store chemicals, oil, beer and hundreds of other products.

Boilers are made out of steel, iron, copper or stainless steel. Manufacturers are increasingly automating the production of boilers to improve the quality of these vessels. However, boilermakers still use many tools to assemble or repair boilers. For example, they often use hand and power tools or flame cutting torches to cut pieces for a boiler. To bend the pieces into shape and accurately line them up, boilermakers use plumb bobs, levels, wedges and turnbuckles.

If the plate sections are very large, cranes lift the parts into place. Once boilermakers have the parts lined up, they use metalworking machinery and other tools to remove irregular edges so the parts fit together properly. They then join the parts by bolting, welding or riveting them together.

In addition to installing and maintaining boilers and other vessels, boilermakers help erect and repair air pollution equipment, blast furnaces, water treatment plants, storage tanks, process tanks and smokestacks. Boilermakers also install refractory brick and other heat-resistant materials in fireboxes or pressure vessels. Some install and maintain the huge pipes used in dams to send water to and from hydroelectric power generation turbines.

Because boilers last a long time, sometimes 50 years or more, boilermakers must regularly maintain them by upgrading parts. As a result they frequently inspect fittings, feed pumps, safety and check valves, water and pressure gauges and boiler controls.