Difference between Fire tube and water tube boiler [with Pdf]

The main difference between Fire tube boiler and water tube boiler is in its name itself. Fire tube boiler indicates that hot flue gases are passed through the tubes and water flows outside over the tube. While the water tube boiler indicates, water is flowing through the tubes that are heated by surrounding hot gases.

Fire tube boiler and water tube boiler

What is a fire tube boiler?

In a fire tube boiler, water is contained in the large size of the shell and a number of coils are passed inside the shell. The hot gases from the furnace flow through the tubes.

Fire tube boiler works at low pressure up to 20 bar.

This type of boiler is generally used in manufacturing plants for process steam generation.

What is water tube boiler?

In a water tube boiler, water flows through the tubes, which are heated externally by hot gases. This type of boiler gives higher pressure steam and higher rate of steam generation.

It is generally used in high capacity power plants.


Sr. No.Fire tube boilerWater tube boiler
1Hot flue gases are passed through the one or more tubes that heat the water in a container.Water is passed through the tubes, which is heated by hot gases.
2Initially, it takes time to start steam generation after firing the boiler.It takes less time for steam generation after firing the boiler.
3Rate of steam generation is lower.Rate of steam generation is higher.
4This boiler generator low-pressure steam up to 20 bar.This boiler generates high-pressure steam up to 200 bar.
5Suitable for heating in chemical processes and also used as process steam.Suitable for high capacity power generation.
6It has less risk of accidents.Higher risk of an accident because of higher operating pressure.
7The initial cost is less.Higher initial cost.
8The size of the boiler is larger for the same rate of steam generation.The size of the boiler is small as compared to fire tube boiler for the same rate of steam generation.
9It takes more floor area.It takes less floor area.
10It requires less skilled operators for its operation.It requires a skilled operator for its operation.
11The rate of heat transfer is slower, hence evaporation rate is lower.The rate of heat transfer is faster, hence it gives a higher evaporation rate.
12The cleaning of boiler is difficult.It is easy to clean this type of boiler.
13Only particular fuel has to use.As it is externally fired, any available fuel for the furnace can be used.
14Transportation and installation is difficult because of the large size of the shell.Transportation and installation is easy as it can be dismantled in number of parts.
15The maintenance is difficult in this type of boiler.It is easy for maintenance.
16Less efficient compared to water tube boiler.It is a highly efficient boiler.
17Example: Cochran boilerExample: Babcock and Wilcox boiler, Lamont boiler


  1. What is the advantage of fire tube boiler over water tube boiler?

    Advantage of a fire tube boiler:
    1) It has less risk of accidents
    2) The initial cost is less
    3) less-skilled operators for its operation

  2. Where are fire tube boilers used?

    Fire tube boilers are used in industries where low-pressure steam is used as process steam, and for heating purposes.

Pratik is a Graduated Mechanical engineer. He enjoys sharing the engineering knowledge learned by him with people.

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