Top 25 Boilermaker Interview Questions and Answers in 2024

Editorial Team

Boilermaker Interview Questions and Answers

A boilermaker is a skilled craftsperson who fabricates steel from plates and tubes. Boilermakers construct, install, and repair boilers, closed vats, and other large vessels or containers to store liquids and gases. They carry out physically strenuous and dangerous tasks. Thus, to help you obtain employment with a reputable company, We have compiled a list of advanced boilermaker job interview questions and answers in this article to assist you in effectively preparing for the interview. It will provide you with all relevant info regarding the skills required for this position and sample interview questions and answers.

1. Why Are You Interested In Working For Our Company As A Boilermaker?

Your organization is well-established in the manufacturing industry and employs many individuals with whom I may engage and learn. Since I began my career five years ago, I have desired to work for a corporation with this reputation. I’ve spent the last few years perfecting my talents as a Boilermaker, and, first and foremost, I’m searching for a role that will allow me to continue honing those skills. In an ideal world, the same things that this employment offers.

2. How Does Boiler Loading Affect Boiler Efficiency?

The boiler operates at its most efficient level, not at full load, but around two-thirds of full load. If the load on the boiler is reduced further, efficiency typically declines as well. As the load decreases, the mass flow rate of the flue gases through the tubes decreases as well. This decrease in flow rate for the same heat transfer area resulted in a small decrease in exit flue gas temperatures, lowering sensible heat loss. At less than 50% load, most combustion appliances require additional extra air to burn the fuel completely. This increases sensible heat loss.

3. What Skills Does A Boilermaker Employee Need To Succeed In Their Job?

Keeping an eye on gauges, dials, or other signs to ensure that a machine is operating properly, Using logic and reasoning to ascertain the relative merits and demerits of various solutions, conclusions, or approaches to problems, Managing the operation of machinery or systems, Conducting tests and inspections on items, services, and processes to determine their quality or performance Giving complete attention to what others are saying, taking the time to comprehend the points being made, asking pertinent questions, and refraining from interrupting at inopportune times.

4. Explain Briefly The Principle Involved In The Process Of Reverse Osmosis’.

When a semi-permeable membrane separates two solutions with different concentrations, water from the less concentrated solution goes over the membrane. It dilutes the liquid with a high concentration of concentration. As a result of pressurizing the solution of excessive concentration, the process is reversed, and water from the solution of high awareness flows into the weaker solution.

5. What Are The Different Methods For Controlling The ‘Extra Air’ In A Boiler?

Portable oxygen analyzers and draft gauges can take periodic readings and allow the operator to adjust the air glide for optimal performance manually.

The most common way is to use a continuous oxygen analyzer with a locally monitored established draft gauge to adjust air glide.

The identical continuous oxygen analyzer can be equipped with a remote-controlled pneumatic damper positioner, allowing the readouts to be accessed from a control room. This enables an operator to manipulate multiple firing systems concurrently remotely.

6. What Are The Primary Responsibilities And Duties Of A “Boilermaker” Employee?

The Boilermaker is responsible for a variety of responsibilities. They construct, repair, erect, test, and maintain boilers, pressure vessels, and tanks and execute structural and plate work on-air, steam, dust, gas, oil, and water containers. Additionally, boilermakers install boilers, occasionally utilize scaffolding, repair and maintain existing boilers and related metal items, and measure, cut, and join piping using welding and brazing equipment. Using hand tools, boilermakers install maintenance holes and feedwater connections in water tube boiler drums. They also inspect boilers, pressure vessels, tanks, and vats for problems such as leaks, weak points, or damaged sections.

7. What Is The Principle Of Mechanical Deaeration Of Boiler Feed Water (Stress Type)?

The stress-type deaerators operate by introducing steam into the feed water via a pressure control valve to keep the preferred operating stress, hence the temperature, at at least 105 °C. Steam increases the temperature of the water, resulting in the emission of O2 and CO2 gases, which are then evacuated from the system. This type can reduce the oxygen content of the substance to zero—0.5 milligrams per liter.

8. What Significant Challenges Did You Face In Your Previous Role? How Have You Handled Them?

When I began this career, I had numerous work-related obstacles, and adjusting to the work environment became increasingly tough. I was unaccustomed to working at such high temperatures and with such intense noise. I was involved in several mishaps, including being struck by things and suffering burns. However, over time, I learned to wear the essential protective gear, such as earplugs, to shield myself from the loud noises. I am now at ease working in this setting and am capable of protecting myself.

9. Describe External Water Treatment Methods?

Aeration is used to remove suspended particles and dissolved gases. Among the methods: Processes that use chemicals to precipitate calcium and magnesium as insoluble substances.

Other precipitating agents, such as caustic soda and sodium phosphate, can be employed when the raw water composition permits. Ion exchange removes hardness from water by passing it over a bed of natural zeolite or synthetic resin without precipitation. If needed, ion exchange operations can almost completely demineralize water, as in large electric power plant boilers.

De-aeration removes gases from the water before it enters the boiler system. Water has around ten mg/1 dissolved oxygen at room temperature—filtration to remove sand.

10. How Would You Describe Your Daily Routine As A Boilermaker?

My job is typically full-time, but we occasionally work overtime to meet deadlines, especially when working on a large project involving different stakeholders. My daily responsibilities include assembling, installing, and repairing boilers, closed vats, and other large vessels or containers that hold liquids and gases. My day-to-day work is physically demanding and, at times, dangerous.

11. Why Is It Necessary To Perform A “Blow Down” On A Boiler?

Water contains dissolved substances. The amount of contaminants in boiler water depends on the untreated input water, the treatment method, and boiler operation. The higher the boiler’s operating pressure, the more sensitive to pollutants. Dissolved particles concentrate in the boiler as the feed water evaporates into steam. These solids produce foaming and water carryover into the steam above a specific concentration. This causes scale buildup inside the boiler, localized overheating, and tube failure. ‘ Blowing down’ maintains the optimal total dissolved solids (TDS) in water. Blowing down the boiler protects the heat exchanger surfaces.

12. Briefly Describe Your Professional Experience And Educational Background Relevant To This Position.

My educational background consists of a high school diploma. I enrolled in a structured apprenticeship program offered by a nearby training institute. It was a four-year program that included paid on-the-job training and classroom instruction. Following that, I apprenticed at a local manufacturer. During this period, I was able to acquire additional practical skills. As a result, I am qualified for this work since I possess the necessary abilities and experience.

13. Which Valve Types Are Utilized For Throttling?

The globe valve is the most frequently utilized throttling valve. However, a needle valve may also be employed. Both of these allow for flow adjustment by modifying the course of the flow via the valve. A globe valve is closed by lowering a plug with a flat or convex bottom onto a matching horizontal seat placed in the valve’s center. By raising the stopper, the valve is opened, allowing fluid to flow. Globe valves are utilized in on-off applications and for throttling.

14. What Are The Personality Traits And Mindsets Of Boilermakers?

Boilermakers are typically realistic people, meaning they enjoy working outside or on a hands-on project. They are also typically enterprising, which means they are natural leaders who thrive on influencing and persuading others. They have a high openness score, which means they are usually curious, imaginative, and appreciate variety. They also tend to score high on the extraversion scale, indicating that they rely on external stimuli, such as people or exciting surroundings, to make them happy.

15. What Is The Difference Between A ‘Chain Grate’ And A Spreader Stoker’ Type Boiler?

Coal is fed onto one end of a moving steel grate in a chain-grate boiler. The coal burns as the grate rotates along the furnace’s length, eventually evaporating as ash. The coal-feed hopper runs the length of the furnace’s coal-feed end. A coal grate is used to regulate the pace of coal feeding into a furnace. On the other hand, a Stoker Boiler is a Spreader. The coal is continuously fed into the furnace over a burning coal bed. The coal fines are burned suspended in the flame; the larger particles fall to the grate and are burned in a thin, fast-burning coal bed.

16. What Is The Most Serious Obstacle You See In This Job?

In this sector, the problem I anticipate is ensuring that our health is protected as we go about our regular routines. As boilermakers, we spend most of our time outside, exposed to UV rays. Due to the present depletion of the ozone layer, numerous radiations are known to cause skin damage and cancer. Additionally, we are frequently exposed to respiratory dangers such as hazardous specks of dust, gases, fumes, mists, and vapors.

17. What Are The Key Characteristics Of A ‘Packaged Boiler’?

Package boilers have the following characteristics:

  • Due to the small combustion space and rapid heat release rate, evaporation occurs more quickly.
  • Numerous small diameter tubes provide excellent convective heat transmission.
  • Systems with forced or induced drafts result in high combustion efficiency.
  • The greater the number of passes, the more efficient the heat transfer.
  • Superior thermal efficiency at lower capacity levels (say, less than 1 ton) than other boilers.

18. Despite The Numerous Difficulties You Encounter On The Job, What Keep You Going?

This job has several difficulties, and I may become demotivated due to these difficulties. On the other hand, challenges are everywhere; you have to grow used to them. Taking on new challenges has always kept me motivated – in my previous position, I was responsible for training our new employees and ensuring that we had a 100 percent pass rate on their final exams. I’m well aware that this task requires a high level of speed, and I’m more than ready to meet the challenge. It is something I enjoy doing.

19. Describe An Instance In Your Last Work When You Made A Mistake.

I made many little errors while learning my craft when I was an apprentice. I entered a boiler without checking to ensure it was clear because I observed my supervisor enter earlier. He instantly corrected me, saying that I cannot presume it is still safe to enter simply because it was previously safe. That stayed with me; I no longer make assumptions. Before making any assumption, I always ask myself if it is safe.

20. What Information Is Required To Calculate A Boiler’s Efficiency Using The ‘Oblique Method’?

The following facts are necessary for calculating boiler efficiency using the indirect approach:

  • The definitive examination of gasoline (H2, O2, S, C, moisture content, ash content)

Oxygen or CO2 content in flue fuel

  • The temperature of the flue gas at 0 degrees Celsius (Tf)
  • The ambient temperature is degrees Celsius (Ta), and the relative humidity of the air is in kilograms per kilogram of dry air.
  • GCV of fuel expressed in kcal/kg
  • Combustible content of ash (in case of solid fuels)
  • GCV of ash expressed in kcal/kg (in case of strong fuels)
  • Interview Questions for Thermal Power Plants

21. Which Skills Do You Possess That Make You The Ideal Candidate For This Position?

I can determine when something is incorrect or is about to go bad. It is critical to identify problems, but not necessarily to solve them. I maintain control of my hand and arm while moving or holding the arm in one place and swiftly and repeatedly adjust the machine’s settings. I’ve worked in this industry for four years and have developed the essential abilities for this position.

22. What Is An Ibr Steam Boiler?

IBR Steam Boilers define any closed vessel with a capacity greater than 22.75 liters that are expressly employed to generate steam under pressure and any mounting or other fitting affixed to such vessel that is completely or partially under pressure when the steam is turned off. They offer the following benefits:

There is no danger of explosion.

  • Made of IBR material
  • Compliance with the law ensures peace of mind.
  • Increased tube life and decreased breakdown
  • Safety Assurance — Third-party inspections conducted by a government-certified third party

23. Tell Us About Your Most Promising Professional Achievement In This Field?

I was named employee of the year in my previous position. This was a significant accomplishment in my field, as it resulted in my promotion and income raise. I devised countermeasures to safeguard our team members’ health, which resulted in increased workplace safety.

24. What Is The Effect Of Coal Sulfur When Used In A Boiler?

Sulfur is oxidized to SO2 and a small amount of SO3 and then reacts with water to generate sulfuric acid. This reaction occurs at a temperature known as the acid dew point, typically around 120 oC. Sulfur trioxide (SO3) generation in coal-fired utility boilers can have a detrimental effect on boiler performance and operation, including equipment fouling and corrosion, air preheater (APH) efficiency loss, increased stack opacity, and the formation of PM2. 5

25. What Are Your Thoughts On The Terms ‘Intermittent Blow Down,’ And ‘Non-Stop Blow Down’ About Boilers?

The term ‘intermittent blown down’ refers to manually operating a valve adapted to the discharge pipe at the bottom component of the boiler shell to bring parameters within specified limits. It necessitates a significant short-term increase in feed water fed to the boiler and may require an additional water supply. During Continuous Blowdown, a continuous and constant flow of focused boiler water is dispatched, or a consistent and regular inflow of feed water is used. Daily operator interaction may be unnecessary once a blowdown valve is configured for a particular condition.


As you have noted, the boilermakers’ interview is quite straightforward, but you must demonstrate to the hiring supervisors that you possess the necessary practical abilities. Additionally, you must demonstrate that you understand the safety precautions that workers in this industry take to avoid injury. If you are given a task to accomplish during the interview, ensure that you complete it promptly. A satisfying job as a boilermaker needs a high level of knowledge, a commitment to quality, and technical abilities. Best wishes for your forthcoming interview.