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Exam Review

Key Facts: NCCER Boilermaker Exam

$76,410

Median Annual Wage

BLS, May 2025

4 Levels

Training Levels

NCCER Curriculum

8,000

OJT Hours Required

Full Apprenticeship

75

Minimum Passing Score

NCCER BLMK34_02

-2%

Job Outlook (2025-2035)

Bureau of Labor Statistics

The NCCER Boilermaker – Pressure Vessel written assessment (BLMK34_02, updated November 2024) is a two-hour, closed-book test of 93 items with a minimum passing score of 75; a basic non-printing calculator and The Pipefitters Blue Book are allowed. Boiler Components (19 items) and Pipe Fabrication (15) are the largest domains, followed by Welding Basics, Cutting Basics and Boilermaker Fundamentals. Boilermakers earned a median $76,410 in May 2025, and BLS projects employment to decline 2% from 2025 to 2035, with about 700 openings a year.

Sample NCCER Boilermaker Practice Questions

Try these sample questions to review concepts for the NCCER Boilermaker exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 150+ question experience with AI tutoring.

1What is the primary function of a boiler?
A.To generate steam or hot water by heating a fluid
B.To cool water for industrial processes
C.To filter impurities from water systems
D.To regulate electrical power distribution
Explanation: A boiler's primary function is to generate steam or hot water by transferring heat from a fuel source to water or another fluid. The steam or hot water is then used for heating, power generation, or industrial processes. Boilers are pressure vessels designed to safely contain this heated fluid.
2Which type of boiler has water flowing through tubes surrounded by hot gases?
A.Firetube boiler
B.Water-tube boiler
C.Cast iron boiler
D.Electric boiler
Explanation: In a water-tube boiler, water flows inside the tubes while hot combustion gases pass over the outside of the tubes. This design allows for higher pressures and faster steam generation compared to firetube boilers. Water-tube boilers are commonly used in large power plants and industrial applications.
3What does ASME stand for in relation to boiler codes?
A.American Society of Manufacturing Engineers
B.American Society of Mechanical Engineers
C.Association of Steam and Mechanical Equipment
D.American Standards for Mechanical Engineering
Explanation: ASME stands for the American Society of Mechanical Engineers. ASME develops and publishes the Boiler and Pressure Vessel Code (BPVC), which is the primary standard governing the design, fabrication, and inspection of boilers and pressure vessels in the United States and many other countries.
4What type of personal protective equipment (PPE) is essential when performing overhead work in a boiler room?
A.Safety glasses only
B.Hard hat, safety glasses, and steel-toed boots
C.Rubber gloves and apron
D.Ear plugs only
Explanation: When performing overhead work in a boiler room, a hard hat protects against falling objects, safety glasses shield eyes from debris, and steel-toed boots protect feet from heavy materials. Boilermakers must always wear appropriate PPE based on the hazards present. Additional PPE such as hearing protection may also be required.
5What is the purpose of refractory material in a boiler?
A.To conduct electricity through the boiler shell
B.To insulate and protect boiler surfaces from extreme heat
C.To increase the weight of the boiler for stability
D.To filter particulates from flue gases
Explanation: Refractory material is a heat-resistant lining used to insulate and protect boiler surfaces from extreme temperatures in the combustion zone. It prevents heat damage to the boiler shell and structural components while helping maintain combustion efficiency. Common refractory materials include firebrick, castable refractory, and ceramic fiber.
6Which welding process is most commonly used for boiler tube repair?
A.Oxy-fuel welding (OFW)
B.Gas tungsten arc welding (GTAW/TIG)
C.Resistance welding
D.Friction stir welding
Explanation: Gas tungsten arc welding (GTAW), also known as TIG welding, is the most commonly used process for boiler tube repair. GTAW provides precise heat control, produces high-quality welds with minimal contamination, and works well on thin-walled tubing. It is especially suited for the alloy steels used in boiler construction.
7What is the minimum safe distance to maintain from overhead power lines when rigging loads?
A.5 feet
B.10 feet
C.20 feet
D.50 feet
Explanation: OSHA requires a minimum clearance of 10 feet from overhead power lines up to 50 kV when rigging loads. For higher voltages, additional clearance is required. Boilermakers must always be aware of overhead power lines and maintain safe distances to prevent electrocution.
8What tool is used to measure the thickness of a boiler tube?
A.Tape measure
B.Ultrasonic thickness gauge
C.Laser level
D.Protractor
Explanation: An ultrasonic thickness gauge uses sound waves to measure the wall thickness of boiler tubes without cutting or damaging them. This non-destructive testing method is critical for detecting tube thinning caused by erosion, corrosion, or overheating. Regular thickness measurements help predict tube life and prevent failures.
9What is the purpose of a safety valve on a boiler?
A.To regulate fuel flow to the burner
B.To release excess pressure to prevent explosion
C.To control the water level in the boiler
D.To monitor flue gas temperature
Explanation: A safety valve (also called a safety relief valve) automatically opens to release excess pressure when the boiler pressure exceeds its set point. This prevents catastrophic overpressure conditions that could cause a boiler explosion. Safety valves are the last line of defense and must be tested regularly.
10What is a tube expander used for in boiler work?
A.Cutting tubes to length
B.Rolling tubes into tube sheets to create a tight seal
C.Bending tubes to specific angles
D.Cleaning the inside of tubes
Explanation: A tube expander (tube roller) is used to mechanically expand boiler tubes into the tube sheet holes, creating a pressure-tight seal. The rolling process plastically deforms the tube wall against the tube sheet, forming a reliable joint. Proper rolling technique and torque control are essential to avoid over-expanding or under-expanding the tube.

About the NCCER Boilermaker Exam

The NCCER Boilermaker – Pressure Vessel assessment checks journey-level knowledge of safe boiler and boiler component assembly and maintenance, including welding, pipe fabrication and stress relieving, oxyfuel cutting, identifying and installing valves, pipe hangers and supports, rigging, and reading boiler drawings and detail sheets.

Exam sponsor: NCCER. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

93-item, two-hour closed-book written assessment (Boilermaker – Pressure Vessel, BLMK34_02); a basic non-printing calculator and The Pipefitters Blue Book are allowed

Time Limit

2 hours

Passing Score

75 (minimum passing score)

Exam / Certification Fees

$150-300 (varies by training provider)

Exam sponsor website

Reported exam pass rate: Not publicly disclosed by NCCER. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

10.8%

Boilermaker Fundamentals

10 of 93 items: boilermaking safety, tools and basic materials (modules 34102-34104)

10.8%

Cutting Basics

10 of 93 items: oxyfuel cutting, plasma arc cutting, cutting and fitting gaskets, and air carbon arc cutting and gouging

11.8%

Welding Basics

11 of 93 items: base metal preparation, welding processes and joint design, welding symbols and quality assurance

8.6%

Pipe Support

8 of 93 items: boiler systems, valves, pipe hangers and supports, fasteners and anchors

5.4%

Rigging

5 of 93 items: rigging and advanced rigging

6.4%

Construction Drawings

6 of 93 items: drawings and detail sheets and advanced boilermaking construction drawings

4.3%

Math

4 of 93 items: advanced mechanical trade math: equivalents, conversions, trigonometry and load weights

20.4%

Boiler Components

19 of 93 items: boiler systems, pressure and nonpressure components, and boiler auxiliaries

16.1%

Pipe Fabrication

15 of 93 items: advanced pipe fabrication, socket weld and butt weld pipe fabrication, boiler pressure components and testing piping systems

5.4%

Tube Work

5 of 93 items: advanced tube work: identifying, extracting, replacing and plugging problem tubes

Preparing for the NCCER Boilermaker Exam

What You Need to Know

  • Passing score: 75 (minimum passing score)
  • Assessment: 93-item, two-hour closed-book written assessment (Boilermaker – Pressure Vessel, BLMK34_02); a basic non-printing calculator and The Pipefitters Blue Book are allowed
  • Time limit: 2 hours
  • Exam / certification fees: $150-300 (varies by training provider) Official sources

Using Our Practice Resources

  • Work through all 150 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

NCCER Boilermaker: Suggested Study Strategy

1Master ASME Boiler and Pressure Vessel Code requirements — code compliance is fundamental to all boilermaker work
2Practice calculating sling angles and load weights for rigging — Rigging is 5 of the 93 items
3Study the different welding processes (GTAW, SMAW, FCAW) and know when each is appropriate for boiler applications
4Understand confined space entry and LOTO procedures thoroughly — Boilermaker Fundamentals, which includes boilermaking safety, is 10 of the 93 items
5Give the most time to Boiler Components (19 of 93 items): boiler systems, pressure and nonpressure components, and boiler auxiliaries
6Study tube sheet work including rolling tolerances and proper expansion techniques
7Review pipe specification schedules and understand the relationship between schedule number and wall thickness
8Practice reading and interpreting weld maps, isometric drawings, and fabrication documents

Frequently Asked Questions

What is the NCCER Boilermaker certification?

The NCCER Boilermaker certification is a nationally recognized credential that validates a boilermaker's knowledge and skills in boiler construction, maintenance, and repair. The program covers four levels of training including boiler systems, welding, rigging, tube/pipe fabrication, refractory installation, and ASME pressure vessel code compliance. Certification is earned by completing NCCER curriculum modules and passing assessments.

How much do boilermakers earn?

According to the Bureau of Labor Statistics, the median annual wage for boilermakers was $76,410 in May 2025; the highest 10 percent earned more than $110,370. Union boilermakers often receive benefits packages including health insurance, retirement, and paid training.

What are the prerequisites for the NCCER Boilermaker program?

Prerequisites typically include a high school diploma or GED, being at least 18 years old, and physical ability to perform demanding work. Most programs require completion of NCCER Core Curriculum (basic safety, construction math, hand/power tools) before starting boilermaker-specific modules. Some training centers require prior welding experience.

How long does the NCCER Boilermaker program take?

The full NCCER Boilermaker program typically takes 3-4 years to complete through a formal apprenticeship, covering four levels of training with approximately 8,000 hours of on-the-job training and related classroom instruction. Each level takes about one year. Some experienced workers may complete training faster through challenge testing.

What topics are covered on the NCCER Boilermaker exam?

The Boilermaker – Pressure Vessel written assessment has 93 items across ten domains: Boiler Components (19), Pipe Fabrication (15), Welding Basics (11), Boilermaker Fundamentals (10), Cutting Basics (10), Pipe Support (8), Construction Drawings (6), Rigging (5), Tube Work (5) and Math (4).

Is the NCCER Boilermaker certification nationally recognized?

Yes, NCCER credentials are recognized nationwide by contractors, owners, and regulatory agencies. The certification is portable, meaning it transfers between employers and locations. NCCER maintains a national registry database that verifies credentials, making it easy for employers to confirm a boilermaker's qualifications.

What is the job outlook for boilermakers?

The BLS projects boilermaker employment to decline 2% from 2025 to 2035, yet about 700 openings are expected each year, all from replacing workers who retire or change occupations. Boiler tubes, heating elements and ductwork still need replacement and maintenance, while the shift away from coal-fired generation reduces demand.