Boilers are closed vessels in which liquids or pressurized gases are heated. They are made out of metals such as steel, wrought iron, copper, and brass. Some boilers are used to supply steam to drive turbines in ships and electric power plants. Others heat fluids under extreme pressure to generate electric power. The primary job of a boilermaker is to install and repair boilers, vats, and other large vessels. This work requires technical skills such as reading blueprints and using tools such as rulers, tape measures, transits, squares, levels, plumb bobs, turnbuckles, hammers, files, power grinders, cutting torches, and welding equipment.

Most boilers are very large and must be made in sections.

• Boilermakers working on installations weld the sections of the vessel together, often using robotic welding systems or automated welding machines. They may work with crane operators to move the heavy sections into place. Then, they smooth and align the edges of each section before bolting or welding the sections into place; attaching components such as water tubes, valves, and gauges; and testing for leaks.
• Since boilers last a long time, boilermakers are often tasked with performing maintenance or upgrades in order to retain and/or increase efficiency. They may need to inspect fittings, feed pumps, safety and check valves, water and pressure gauges, or boiler controls.
• They may have to install new parts, strengthen joints, patch weak spots, replace entire sections of boilers, or even take boilers apart to fix leaks. Boilermakers may also help erect and repair air pollution equipment, blast furnaces, water treatment plants, storage and process tanks, stacks, and liners.

Boilermakers refer to themselves as “down and dirty” professionals, and their job tends to be more hazardous than many others. Boilermakers work both inside and outside, and are therefore exposed to all types of extreme conditions. Outside work might involve maneuvering on scaffolding to work on water storage tanks or huge pipes used in dams to send water to and from hydroelectric power-generating turbines. Weather conditions a boilermaker may have to work in include both mild conditions and extreme heat and cold. Work frequently takes place in hazardous environments such as the insides of vats or boilers, which are often dark, damp, and poorly ventilated. In any of these environments, boilermakers must handle heavy objects and climb to great heights, making the work both strenuous and demanding.

In order to be accepted into an apprenticeship program, applicants must be at least 18 years old, be a high school graduate or have a GED, and be legally authorized to work in the United States. Priority is often given to those with welding training or certification. Local unions publicize apprenticeship opportunities by notifying local vocational schools and high school vocational programs. In order to be certified as a fully-qualified journeyman, apprentice boilermakers must complete a four-year training program which consists of 6,000 hours of on-the-job training and 576 hours of classroom instruction. The training is offered through trade unions, employers, or a combination of trade and technical school training and employer-provided training. Each year of the program requires at least 144 hours of classroom instruction in subjects such as math, hand and power tool basics, set-up and assembly rigging, plate and pressure welding, and blueprint reading.

The Bureau of Labor Statistics (BLS) Occupational Outlook predicts faster than average growth and good job opportunities for boilermakers. The growth in employment is expected to be about 19 percent over the next 10 years. Growth will be driven largely by the need to maintain and upgrade existing equipment rather than the need to replace existing, older boilers. Additionally, federal policies such as the Clean Air Act will require utility companies to continue upgrading their boiler systems. It will also encourage the construction of more environmentally sound and higher efficiency clean-burning coal, wind, and solar power plants.

Boilermakers earn a very attractive wage. This trade, like others, provides opportunities for advancement to supervisory positions that increase the base wage. The median annual wage is approximately $52,260. The middle 50 percent earn between $41,210 and $64,300. The lowest 10 percent earn less than $32,480 and the highest 10 percent earn more than $76,160. Boilermaker apprentices receive 50 to 65 percent of the wages earned by journeymen. The rate increases steadily after every 1,000 hours of training.

Most boilermakers work in the construction industry for contracting firms or government agencies. While some work 40 hours a week as salaried employees, many employed in construction work irregular hours. When contracts end there may be periods with no work. However, these times are often offset by contracts that require long hours. These may require workers to remain away from home for considerable amounts of time.