Things You need to Know about Boiler Mountings and Accessories

The boilers are most commonly used all over the world for various industrial and heating applications. The main function of the boiler is to boil the fluid at a controlled temperature and environment. The boiler contains different mountings and accessories that help to improve its performance and safety.


Some safety devices and controlling tools are mounted on the surface of the boiler; these are known as boiler mountings. Similarly, various devices are mounted on your boiler to ensure its efficient and smooth performance. These devices are known as boiler accessories. This article deeply explains the different boiler mounting and accessories.

What Are Boiler Accessories?

Boiler accessories are integral to any boiler but are not installed on the boiler’s surface. These accessories ensure the efficient and smooth performance of your boiler.

Feed pumps, economizers, and superheaters are some important examples of boiler accessories. The important part here is to remember that these accessories are used to increase the efficiency of the boiler.

What are Boiler Mountings?

Boiler mountings are the devices or elements that are mounted on the surface of the boiler to ensure the safe and smooth operation of your boiler. They are present on the boiler’s body to protect it during processing and have proper control over the steam generation cycle.

Boiler Mountings

Extremely high pressures, fluctuating steam pressures, low water, vacuum shell collapse, steam backflow, and pumping backflow are some major factors that can damage your boiler. So, the boiler mountings protect the boiler from these threats and make the whole boiling process safe and smooth.  

Pressure gauges, water level indicators, and safety valves are some examples of boiler mountings. You can also observe that these mountings play a very important role in safely executing the whole boiling process.

Boiler Mountings

Following are the major boiler mountings:

  • Safety valves
  • Pressure gauge
  • Water level indicator
  • Steam stop valve
  • Fusible plug
  • Feed check valve
  • Blow-off valve
  • Automatic water feed regulator
  • TDS sensor and sample
  • Manhole
  • Pressure gauge connection

1) Safety Valves

Boiler Safety Valve

These types of mountings are usually present in the steam boiler. The main function of the steam valve is to prevent an explosion in case of extreme steam pressure inside the boiler.

A normal working pressure is usually set in the boiler to ensure proper operation. So, whenever the boiler’s pressure exceeds its threshold, these valves automatically open and release some extra steam pressure to maintain the boiler’s inner steam pressure.

Hence, we can claim that the main purpose of the safety valve is to save the boiler from damage by controlling and evacuating the excess steam pressure.

The following are the most commonly used safety valves:

  1. Spring-loaded safety valve
  2. Lever safety valve
  3. Deadweight safety valve

2) Pressure Gauge

Pressure Gauge

The pressure gauge is also one of the most important boiler mountings. The main function of the pressure gauge is to calculate the steam pressure within the boiler. The pressure gauges are installed on the front side of the boiler. Therefore, the boiler operator can easily record the steam pressure readings.

There are a variety of pressure gauges on the boiler mountings, the most important of which is the Bourdon pressure gauge. It is used widely in industry.

3) Water Level Indicator

It is one of the major boiler mountings. The boiler usually contains two water level indicators. The water level indicators are mounted on the boiler’s front side.

The main purpose of this unit is to gauge the water level in a boiler. So, when the water level becomes less than a specific level, the water level indicator initiates an alert to add more water to the boiler.

4) Steam Stop Valve

This valve uses to regulate the steam flow in the boiler. It functions essentially as a boiler’s steam regulator and is also known as a junction valve. The steam stop valve completely stops the steam flow when needed.

There are some special types of valves that divert the flow of the steam at an angle of 90 degrees; they are known as junction valves. Some valves are installed in the pipelines of your boiler that permit the steam to flow in a direction, and they are known as the stop valves.

5) Fusible Plug

Fusible Plug

The fusible plug extinguishes the fire of the burner whenever the water level drops less than a specific value. This specific value is predetermined based on the system’s process requirements and needs.

A metal with a minimal melting point is used in the manufacturing of this plug. The temperature rises as the water level drops, resulting in the valve melting. With the melting of the valve, the steam swiftly flows to the furnace and starts the fire.

6) Feed Check Valve

Feed Check Valve

Whenever the water level lowers, some extra water is supplied to the boiler to maintain the level of water. This extra water is called feed water.

As the pressure inside the boiler becomes very high, the pressure of the feed water has to be increased to a proper value with the help of a pump. This feed water is fed to the boiler using the feed check valve.

The main purpose of this valve is to maintain the water flow between the boiler and the pump. It prevents the backflow of the water when the feed pressure gets lower or when the pump stops working. This valve is mounted on the feed pipe near its end and close to the boiler.

7) Blow-off Valve

The blow-off valve is used to extract the residues accumulated at the base of your boiler in a periodic manner. The blow-off value removes these remains while the boiler is working and empties the boiler so that processing can continue smoothly.

Due to the high steam pressure inside the boiler, with the opening of the blow-off valve, a strong flow of water exits the boiler, which also carries the residues with it.

8) Automatic Water Feed Regulator

It ensures an accurate water level in the boiler. Various water control systems are used in boilers having elevated evaporation rates.

9) TDS Sensor and Sample

TDS Sensor

To monitor the overall solid dissolved in the water of the boiler, many advanced boilers have TDS sensors. After monitoring the overall solid dissolved in the water, these sensors then compare this valve to the setpoint.

In case of high values, this sensor turns on the alarms to alert the boiler operator. If the dissolved solid content increases, some extra water is fed into the system to maintain the solid content amount.

10) Manhole

Boiler Manhole

It is one of the most important boiler mountings. Multiple manhole gates are present in the boiler. These are used to clean, maintain, and inspect the internal components and boiler tubes by the working staff. The manhole is typically installed in a water drum and a gate steam drum.

11) Pressure Gauge Connection

Pressure gauge connections are fixed on the fronts of the boilers. The purpose of the pressure gauge connection is to record the pressure readings in the boiler drums and superheaters. Most of the time, the Bourdon type is used in industries.

Boiler Accessories

The major accessories of the boiler are given below:

  • Air pre-heater
  • Economizer
  • Feed pump
  • Soot blower
  • Pressure reducing valve
  • Injector
  • Superheater
  • Steam separator

1) Air Pre-Heater

The furnace of the boiler is fed with heated air. This air is also heated with the help of the wandering heat coming out of the boiler. This preheated air also helps to improve the combustion process in the furnace due to the high temperature from both the burner and this preheated air. Hence, air preheaters eventually boost the thermal effectiveness of the boiler.

The following are some of the main benefits of an air preheater:

  • Enhances the rate of steam generation.
  • Good and clean combustion without a lot of smoke, ash, or soot.
  • It can work with low-grade fuels.

2) Economizer

Super heater

A lot of heat comes out of the boiler with combustion gases. Here, this wandering heat is recovered before leaving the chimneys to the environment.

These heated gases are used to heat the economizer’s feed water. In the boiler system, the economizer is installed in the route of the gases. Hence, the efficiency of the boiler increased as this process saved a good amount of fuel that would have been needed to heat the feed water separately from another heat source.

3) Feed Pump

In industrial boilers, high-pressure water is supplied into the boiler using a feed pump. As we know, the inner steam pressure of the boiler is already very high, so the feed water pressure should be higher than the internal steam pressure in order to keep the boiling process smooth and safe.

Usually, the pressure of the feed water is about 20 percent more than the internal steam pressure of the boiler. Reciprocating pumps or centrifugal pumps are most commonly used to feed water in boilers.

Read More: Reciprocating Pump Vs Centrifugal Pump

4) Soot Blower

Soot Blower

Soot is produced as a result of the combustion process and gets built up on the furnace pipes or tubes. This soot can sometimes block the gas flow and may mix a little with it, reducing the performance of the boiler. So, to prevent the gas passage from clogging, soot blowers are installed in the plant to remove soot from the furnace tubes.

5) Pressure Reducing Valve

The pressure-reducing valve maintains a constant pressure on the distributing side of the boiler.

6) Injector

The injector operates in the same manner as the feed pump. The injector is used when the workers do not find a specific place to attach the feed pumps. The velocity and pressure of the feed water in the injector are increased through the kinetic energy of the steam.

7) Superheater

Super heater

The main function of the superheater in the boiler is to increase the steam temperature more than the saturation temperature. This dry saturated steam produced inside the boiler is passed by some tubes placed in the pathway of the flue gases, where it gets some more heat from the flue gases.

As a result, the steam converts into superheated steam, and its temperature becomes higher than the saturation steam.

8) Steam Separator

The steam is used in the turbines to generate electricity. The steam coming from the boiler is moisturized and wet. This wetness in the steam is removed with the help of the steam separator or the moist separator.

The steam separator separates all the water drops from the steam and makes it dry. The steam separator is placed in the main pipe and removes the wet steam, as the wet steam decreases thermal efficiency.

Boiler Mountings vs. Boiler Accessories

Boiler MountingsBoiler Accessories
Elements that guarantee the safety of the boiler.Elements that guarantee the efficiency of the boiler.
Essential parts of any boiler.These are also essential parts of any boiler.
Mounted on the boiler.Not mounted on the boiler.
They control the fluid parameters of the boilers from inside the boiler.They control the fluid parameters of the boilers from outside the boiler.
Their main purpose is to keep the boiler safe.Their main goal is to make the boiler more efficient.
The boiler mountings improve the life of the boiler.The boiler accessories improve the boiler’s efficiency, not its life.
The boiler cannot work without the mountings.Boilers can work without boiler mountings.
They eliminate boiler accidents.They do not take part in eliminating accidents, but they increase their performance.
They are the internal parts of any boiler.They are the external parts of any boiler.
Examples: blow-off cocks, pressure gauges, safety valves, water level indicators, fusible plugs, and stop valves.Examples: superheater, feed pump, air preheaters, economizer, steam separator, injector, etc.

Leave a Comment