Boiler Problems

Your best course of action is to return the boiler to the original spec. Refractory is a much better insulation than air. If you are experiencing "burning through", there must be some breach in this insulation, allowing hot gasses to flow to the outside.

My questions:

What type of boiler? A diagram of the wall construction would help.

What type of refractory, hard, or blanket?

After instillation, all refractory will shrink somewhat, creating voids, and must be repacked after an initial bake-out.

If I get a response back, I will elaborate.

Many thanks for your response. Part of our problem is that we don't know what the original spec was. This is Africa and the normal rules don't apply! Modifications in the past were not recorded or if they were the records are lost. The original databook is no longer available. I hope to have located some original drawings which the manufacturer still has although they stopped making boilers shortly after this one.

The refractory lining which will be used (and is probably what was used previously is Refcast 50) . I agree that the refractory lining was probably defective to allow so much heat through, although there was no obvious path through the lining. I am told that in the past coal has built up on the external steel surface of the stoker and started to burn so it is possible that some damage to the external section of the stoker started in this way.

The photograph below shows the area after removal of the stoker with the main area showing damage to the smoke box - the remains of the stoker shell are also visible

The sketch below shows the layout in this area.

Many thanks also to other contributors - my apologies if I get the etiquette wrong - I am new to this!

I concur with Bricktop that the original specifications (presuming they were done properly) should be met. Is there reason to believe there was something wrong with the initial design? Or did the burnout result from age or damage?

I have repaired many of these burnout places on water tube boiler walls ducting and hoppers in the past. If it is burning up the outside steel that covers the refractory then the refractory has stopped working for some reason. We usually start cutting out the outside layer of steel to we get the problem area identified repair insulation/refractory and then replace the outer steel. I am not sure what type of refractory you have, it could be insulating or not and this would make a big difference. I would assume you would repair by spraying a 3000 degree high alumina refractory Gunnite. Some of these will have a layer of insulating refractory between the steel and the harder high heat inner refractory. If you suspect that any of these old materials are asbestos then I would suggest having an asbestos inspector to look at it before disturbing it further.

pipewelder

My friend rules vary Country to Country. I believe that your Boiler Inspector/Stationery Engineer from the Ministry should first survey this and give instruction to be carried out only by a certified Contractor who, after completion will again call the Inspector to visit & certify before you are allowed to continue with the boiler. Is it not how it is done in your Country?