9 replies to this topic

[rishirga]

We have steam boiler for one of our LNG floating vessel. we are experiencing heavy rust insdie the boiler and looking for some possible solutions or chemicals?

 

I have attached few pictures for your referencces.

 

Thanks

 

Rishi

Attached Thumbnails

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[fallah]

rishirga,

 

A general question will be faced with general answer...

 

It depends on type, thickness and chemical composition of the rust/deposit; acid cleaning might be a proper option...

[rishirga]

Fellah

 

Thanks for your suggestions.

 

It seems significant rust to me, i am worried about rust can convert from Ferrous to Ferric in an oxidized acidic solution.

 

Regards

 

Rishi

Edited by rishirga, 15 January 2016 - 12:24 AM.

[fallah]

 

It seems significant rust to me, i am worried about rust can convert from Ferrous to Ferric in an oxidized acidic solution.

 

 

rishi,

 

Appears you should worry about converting the ferric to ferrous; because it shows the solution of bare steel due to the reaction between ferric and bare steel...

[fallah]

Rishi,

 

To prevent removing bare steel due to reaction with ferric iron to ferrous, a trick is adding a reducing agent such as Hyrazine to reduce ferric iron to ferrous condition before it could react with the bare steel... 

[rishirga]

Fallah;

 

I can understand your drill. You are willing to suggest Inhibited Acid cleaning ?

[fallah]

 

You are willing to suggest Inhibited Acid cleaning ?

 

Rishi,

 

Yes, of course...inhibited acid cleaning can be a proper solution...

[rishirga]

Thanks.

[martin_h]

If this was my boiler I would be very worried by the presence of red iron oxide.  This is clear evidence of oxygen ingress.

 

The presence of the amount of oxygen to cause this amount of scale indicates a problem with either de-aerator or hot well and you should examine the whole condensate system to see where the oxygen Is getting in.

 

If you don't do something you will either get a shell failure due to Oxygen pitting , or in the worst case you can get oxygen induced cracking that can cause a catastrophic failure.

 

If the boiler has been open to atmosphere for some time then this might be a cause.

 

Whatever you do, you must get it cleaned up. inhibited acid clean is the way to go, I suggest you talk to a boiler treatment company to get a method.

 

Normally the inside of a boiler should have a black to grey colour which is caused by the presence of a thin layer of magnetite which protects the boiler metal.  In my 30 odd years working with boilers I have never seen one as bad as this.

[rishirga]

Martin;

 

Thank you for your suggestions. Yes, boiler was kept in open atmosphere after factory testing and there was no layer insider the boiler to protect the metal. I am discussing for Inhibited hcl cleaning with supplier and willing to proceed with one of chemical also which will coat the surface of the inside the vessel to protect the corrosion.any further suggestions are higly appreciable.