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 store and process chemicals, oil, beer, and hundreds of other products. 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 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 in making or repairing boilers. For example, they 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, large cranes lift the parts into place. Once they have the parts lined up, they use metalworking machinery and other tools to remove irregular edges so the parts fit together properly. They 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 and 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 and upgrade parts. They frequently inspect fittings, feed pumps, safety and check valves, water and pressure gauges, and boiler controls.