Is Boiler A Pressure Vessel: Facts You Should Know

In this article we will discuss different facts related to Boiler and Pressure Vessel to know the answer for the query “is boiler a pressure vessel?”

Boilers are a special type of Pressure Vessels.Boilers are common devices for industrial heating and humidification applications. Pressure vessels are large containers or tanks designed to operate at pressures much higher than atmospheric pressure.

Define A Boiler

According to the Indian Boiler Act, a Boiler is a closed pressure vessel with capacity exceeding 22.75 litres used for generating steam under pressure.

A Boiler is a device used for generating steam for power generation or heating purposes and hot water for heating purposes. Industrial Boilers are designed in such a way-that it can cope with high pressures, Boilers are fabricated by welding thick steel plates together.

Any defects in making a Boiler may result in forces that may create a dangerous situation.

is boiler a pressure vessel
An Industrial Boiler; Image Credit: Wikipedia
A welded steel Pressure Vessel; Image Credit: Wikipedia

Difference between Boiler and Pressure Vessel

A pressure vessel is a container which contains the fluids ,gases or combination at high pressures. whereas a boiler is a container that contains the liquid that is water such that it can be boiled by the heat source at higher temperatures.

The different facts to know “Is Boiler a Pressure Vessel” are listed below:

 BoilerPressure Vessel
IntroductionBoilers are special type of closed vessels in which fluid mainly water is heated. Heated fluid is then used for different purposes.Basically a closed container with a pressure difference between inside and outside the container. The inside pressure is usually higher than the outside except for some isolated situations.
UsesThe main function of a Boiler is to either produce hot water or steam.Mainly used to store gases and liquids at high pressure.
Area of useDifferent sectors like food industries, beer brewing process, domestic purposes, commercial and industrial uses, textiles, thermal power plants, power sectors, sugar plants etc.Different sectors like gas and oil industries, chemical industry and power plants, distillation towers use Pressure Vessels for various purposes.
Main ComponentsA Furnace is an essential part of a Boiler where fuel is burned to produce heat.The main components of a pressure vessel are shell casing, nozzle, support or saddle and head or end closures.
TypesDifferent types of Boilers are Fire tube boiler, Water tube boiler, High pressure and low pressure Boiler, Horizontal and Vertical Boiler, Externally and Internally Fired Boilers etc.Different types of pressure vessels are autoclaves, high pressure vessels, process vessel, expansion tank, heat exchanger, vacuum tanks, ASME pressure vessel, Boilers, thin walled pressure Vessel etc.
Materials usedSteel. Alloy steel, copper, brass, wrought iron etc are used.Steel, nonferrous materials(aluminum, copper), metals(like titanium, zirconium)plastics, composite, concrete etc.
Boiler Vs Pressure Vessel

These vessels are always designed carefully to cope with the high operating temperature and pressure. In most of the countries, vessels like Boiler and Pressure Vessels over certain size and pressure must follow certain regulating act mainly to ensure compliance with safety, security and design standards.

The use of Boiler starts much before than Pressure Vessel. Sudden rapture of a Pressure vessel or a Boiler can be resembled with hazardous explosion which leads to extensive physical injury and property damage, therefore safety and integrity are of fundamental concern in design.

Boiler and Pressure Vessel Code

American Society of Mechanical Engineers (ASME) develop standards and regulation codes to define and secure Boilers and Pressure Vessels safely, it includes a wide range of rules and directives.

Boilers and Pressure Vessels can be dangerous and may lead to fatal accidents due to this reason design, manufacture, and operation are strictly regulated by Engineering authorities followed up by legislation. In the United States the ASME Boiler and Pressure Vessel Code(BPVC), and in Europe, the Pressure Equipment Directive Code is applied.

An authorized inspector has to sign off on every new vessel constructed, each vessel must have a nameplate with all the required information about the vessel. Across over 100 countries the ASME code is accepted. The adding of the ASME certification mark to your pressure equipment encourages greater trust among your business partners, end-users, and authorities.


In this article we try to know “Is Boiler a Pressure Vessel ?”. Before wrapping up the article we can say Boilers come under the Pressure Vessel category and Boilers have almost all the characteristics for which we can say Boilers are similar to Pressure Vessels

Sangeeta Das

I am Sangeeta Das. I have completed my Masters in Mechanical Engineering with specialization in I.C Engine and Automobiles. I have around ten years of experience encompassing industry and academia. My area of interest includes I.C. Engines, Aerodynamics and Fluid Mechanics. You can reach me at

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