Boiler Inspection Programs are supposed to enforce nationally adopted standards which govern the installation, operation, maintenance, and repair of boilers and pressure vessels in commercial and public buildings that are part of the building system. Inspections are conducted periodically by State Inspectors or by inspections who have been commissioned to perform these inspections by the Boiler Inspection Program (insurance companies). The purpose of these inspections is to verify that the safety requirements have been fulfilled. As a precautionary measure, the Boiler Inspection Program was established in order to ensure the safety of the facility, as boilers are capable of exploding and causing serious injury and death.

A boiler inspection is an essential part of every business’ daily operations that uses industrial boilers as a part of their regular workflow. 

When boilers are in operation, they are subject to extreme pressure and temperature swings that can range from hundreds to thousands of degrees Fahrenheit as a result of varying levels of pressure.

If a boiler is not inspected periodically, a flaw in the boiler could go undetected for a long time.

There is always the possibility that a small problem that is not detected today will grow larger and worse over time, and in the worst case, it could even lead to a catastrophic failure which in turn could lead to an explosion injuring or even killing those who are working in the area.

A boiler inspection is a crucial step in preventing catastrophic failures by identifying and tracking flaws so that proper maintenance procedures can be followed to prevent the failure taking place.

A guide to boiler inspections is given here to provide you with an overview of the basics of what boilers are, what they do, and what is involved during a boiler inspection. It also helps you to appreciate the work an inspector of boilers does, and how industries that rely on boilers can benefit from the use of drones in their inspections.


A boiler is a closed vessel that is used to create hot water or steam, and the purpose of this vessel is to produce heat. After the steam is generated, it is used as a power source for various purposes (a few examples will be given in the following section).

A boiler is typically used to create steam by converting fuel like coal, oil or gas into heat through the combustion process. This heat then gets applied to the water contained within a boiler and, as the water becomes heated, it begins to turn into steam as a result of the boiler’s heating.


It is possible to use the steam that is produced by a large boiler as an energy source in various ways, including:

  • Power generation. The steam can be used within various facilities in order to power various components, such as pumps, blowers, or turbines that generate electricity through the use of steam.
  • Production. A company that utilises steam-driven power to make its products will have an edge over the competition because they can provide power, extreme heat required for production, and sterilization methods.
  • Climate control. Additionally, steam can be used as a means of powering air conditioning and heating units so that equipment of different types can be kept at a constant temperature or the working environment and temperature for the employees can be kept comfortable.

Inspecting steam boilers is an important task in order to ensure that they are maintained in good condition, in order to find any potential problems before they become bigger ones.


A boiler’s purpose is to transfer as much heat from combustion into the water in the boiler as possible by using conduction, convection, and radiation. These methods are used to increase the efficiency of the boilers. 

A more efficient process will result in greater savings for the company and the more efficient it is, the more savings there will be.

It is important to understand that a boiler does not simply heat water for the purpose of producing steam. The conditions within the boiler are also optimized so that pressure is increased in order to increase the boiling point of the water. It works the same way as it works in pressure cookers, where pressing down on an airtight seal speeds up the process of bringing up hot water to boil or every other aspect of cooking in general.

So how does an industrial boiler work?

With the right combination of pressure, an efficient form of fuel, and an efficient mechanism for transferring heat to water, a boiler can create huge amounts of steam. Steam is produced by combining pressure, an efficient fuel source, and an efficient mechanism for transferring heat to water.

Steam is generated in boilers through the use of various types of fuels, which in turn create heat. These fuels include:

  • Coal. Coal is one of the most common fuel sources for boilers.
  • Gas. The term gas refers to either propane or natural gas, depending on the source
  • Oil. The term oil refers to a fluid derived from petroleum, such as gasoline or diesel
  • Wood chips or pellets. The only boilers that can use wood pellets as fuel are biomass boilers.


Boilers are available in a wide variety of types, shapes, and sizes. Basically, they differ in the way the heat used to turn the water into steam is conveyed to or through the water to make it turn into steam through the use of different methods.

The following are some of the most common types of boilers:

  • Fire-Tube Boiler. The fire-tube boiler works by burning fuel inside it, and by transferring the heat created by the burning to water inside the tank, the heat produced is transferred to generate steam by means of tubes. Fire-tube boilers are among the cheapest types of boilers that may be made since they can be designed and constructed in a relatively straightforward manner. As a result, they are generally limited to low- and medium-pressure applications because their shells are not thick enough to withstand high pressures. Therefore, they can be used in low and medium pressure applications.
  • Recovery Boiler. The pulp and paper industry makes use of recovery boilers to heat pulp and paper. In order to generate superheated steam from the pulping process, black liquor (a byproduct of pulping) is burned and inorganic elements are recovered.
  • Water-Tube Boilers. Water-tube boilers are similar to fire-tube boilers, but instead of firing fire tubes in a furnace that then transfers heat to the water inside of a tank, water tubes are heated inside the furnace instead of heating fire tubes that then transfer heat to the water inside of the tank. Boilers with water tubes are more efficient than those with fire tubes, however they are also more complicated, and therefore more expensive, than those with fire tubes.
  • Biomass Boiler. The concept of a biomass boiler is similar to that of a gas-fueled boiler that produces heat from wood chips, wood pellets, logs, and other types of biomass instead of fossil fuels, such as oil, gas, or coal. They can be used to produce electric power as well.


The oil & gas, power generation, chemical, and steel industries are some of the biggest industries that make use of boilers in their work. 

It is important to remember, however, that boilers play a significant role in numerous other industries as well. Here is a list of some of them:

  • Alcohol distilleries
  • Cement
  • Fertilizer
  • Paint
  • Pharmaceuticals
  • Plywood
  • Pulp and Paper 
  • Rubber
  • Sugar 
  • Textile


The inspectors performing the inspection have a set of items which must be visually inspected both inside and outside the boiler as part of the inspection process.

The goal of both the external inspection as well as the internal inspection of the boiler is to check each component of the boiler visually in order to identify potential problems or wear and tear which may need to be addressed later on.

While external boiler inspections are easy to perform and don’t require that any special preparation is done, beyond making sure that the boiler is cool and depressurized, internal boiler inspections may be difficult due to the difficulty of gaining access to various parts of a boiler. 

As part of a manual internal boiler inspection, an inspector must physically enter the boiler, which requires the company to build scaffolding so the inspector can stand on during the inspection, in order to carry out the inspection. As soon as the inspection has been completed, the scaffolding must then be taken down after the inspection is complete.

When scaffolding is required for the inspection, it can increase the downtime needed to complete the inspection by several days, and often, scaffolding can cost tens of thousands of dollars to construct and remove, increasing the time and cost of the inspection process.



  • Boiler room condition. Inspection inspectors will usually examine the room in which the boiler is installed as part of an inspection of the boiler to make sure that there are no flammable materials or other obstructions that could cause a safety hazard when the boiler is in use.
  • Nameplate. As an inspector, it is often your responsibility to read the boiler nameplate, as that is where you can find out the type of boiler, when it was made, the maximum pressure allowed in the boiler, as well as what controls should be installed for the boiler based on ASME manufacturing code requirements and NBIC (National Board Inspection Code).
  • Safety valve. The safety valve on a boiler is, from a safety standpoint, one of the most important parts of the boiler, which is why you should pay close attention to the safety valve during an inspection of a boiler. There is an important component of the boiler that acts as a safety valve (also known as a relief valve) if there occurs any damage in the boiler that can lead to an explosion caused by overpressurization.
  • Control safety devices. A high level of importance is also placed on control safety devices in terms of safety. There are many examples of these switches, including the fuel train, the emergency shut-off switch, and the operating switch. An inspection of a boiler is not complete without a visual review of each one of these devices in order to ensure continued safe use of the boiler during the course of the inspection.
  • Piping. Piping is used in the boiler room to transport water and fuel into and out of the boiler. There is a very important aspect of an inspection for a boiler which is the inspection of the piping. This is for two reasons; first, to ensure it is still in good working condition and second, to make sure it is the right kind of piping for the way it is being used according to ASME standards to ensure it is in good working condition. As part of the flue pipe inspection process, it is also important to make sure that the connections between the flue pipe and the boiler room are correctly sealed so that carbon monoxide cannot build up.
  • Fresh air for combustion. When an inspector conducts an inspection of a boiler, he will review the boiler’s combustion air requirements in order to ensure that the air pathway is open and the boiler is receiving an adequate supply of fresh air, given that the boiler requires the correct ratio of fuel to air to operate properly. Thus, the boiler needs the correct amount of fresh air for the burners to function properly.


  • Walls and surfaces. A thorough examination is conducted of the boiler’s internal walls and surfaces, checking for signs of leaks, corrosion, overheating, or other structural problems that may exist within the boiler.
  • Waterside areas. An inspection is carried out of all waterside areas of the boiler, including the blow-off pipes, the water connections, and the steam lines.
  • Fireside conditions. The internal conditions of the boiler, including the superheaters, deaerators, and economizers, are inspected at all times during fireside inspections.