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Reasons why marine Oil Boiler Back Fire

boiler back firing

In most cases, boiler backfiring may occur during normal operation, which places a high risk to the ship and her operators.

On this article, I’m going to list the major things that may lead to boiler backfiring. But firstly, let’s understand the basic types of boilers which are used on board ship.

As per normal standard on shipbuilding, most vessels with the engine above 3000kw usually built in with boilers, for the purpose of fuel heating, jacket water warming, etc. The boilers which are usually installed on board ships are basically two types ;

Types of ship boiler

Oil Boiler

This type of boiler maybe installs on board ship as an auxiliary or main propulsion boiler.

As per fire triangle, which comprises of; Fuel, oxygen and Ignition, this type of boiler is built with separate burner made up of an electric motor ( which drives the fan and fuel pump), ignition electrode, injection nozzle, and nozzle housing…… Read more details on Reasons why marine Oil Boiler Back Fire Reasons why marine Oil Boiler Back Fire

Exhaust or Economiser boiler ;

Since the exhaust outlet of the main marine diesel engine is of high temperature, it’s utilized by installing tubes in an expanded area away after the turbine.

While the exhaust passes through these tubes, it heats the fluid ( thermal oil or water) inside it. According to some shipbuilders, they provide bypass flaps valves, which gives you the possibility to send the exhaust out without passing through the tubes.

Furthermore, as you may know, the method of producing steam, the mentioned above process, helps us to achieve steam or heat.

Now, when we talk about boiler backfire, it always happens on the oil boiler. This backfire happens as a result of the followings ;

Cause of boiler backfire

Clogged boiler exhaust gas outlet ;

Regular cleaning of the boiler furnace is very recommended, to remove carbon deposits between the tubes. This will allow proper blow through to avoid excess gas in the furnace, which may find its way out when fuel and ignition applies. Note, this could lead to explosive or fire hazards in case the boiler is not being stopped as fast as possible.

Blower flap full open;

Sometimes, the blower flap regulator may go out of order ( defective ), instead of reducing the air flow to 30….90% before ignition time, it will remain on the same blow through the window. It’s important to regularly inspect the performance of this flap regulator motor.

Nozzle leakage or fuel drop back;

Depending on the makers’ recommendations, nozzles are meant to spray some …..mm distance away into the funnel where burning takes place. Therefore having some leakage behind may lead to fire drowning backward.

Low oil pressure or too much oil deposits in the firing chamber;

Low fuel pump pressure can also result in nozzle not able to spray fuel away as required. Check fuel pressure and maintain as per makers recommendations.

Air regulator micro switch malfunctioning:

This is a very important and most dangerous point you need to check always. Let’s say you are using HFO ( heavy fuel oil ) to run your boiler,and the air regulator purging timing is less than normally required time and air pressure for deposited fuel purging, it can lead to an explosion or backfire in case there are remains of fuel vapor inside the boiler furnace and your ignition turns on.


With all of the above-mentioned causes of boiler backfire and remedies, I strongly believe that you can be able to solve problems in relation to backfiring of the auxiliary or main boiler.

If this article helps you, let’s have your comments below. Also, you can share with friends who may be in need of this article.

Also take safety first to avoid accidents or fire hazards. Proper watchkeeping is always important onboard.

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