The Steamboating Forum

On the SBA forum there is a thread by Philip Martino regarding painting the inside of his VFT with a product called "Apexior No 1 internal boiler paint"

It was recommended to him by his boiler inspector and is apparently acceptable practice (even 2 coats!) as it's mostly graphite.

It's quite a new concept for me as I always understood that anything coating the inside of the boiler would be detrimental to heat transfer and eventually the integrity of the boiler material.

If you have an SBA membership the thread can be viewed here:
http://sbaogb.camp9.org/Default.aspx?pa ... eid=810137

Hi Wes,

Up in the middle of the night with a bad cold so I Googled this stuff and read for a while.

At the thickness that they recommend application (105 microns or about .004 inches) I suspect that the insulation properties would be fairly minimal. In a non-condensing boiler, the crud buildup would be that thick in no time at all.

In a condensing system with any sort of attention to the condition of the feed water at all, I suspect it would not be worth the trouble.

Reading the recommended surface prep, I wouldn't think of coating an existing boiler. If this stuff came loose, it would gunk up everything.

That said, I have customers who want heat exchangers where this stuff might be a good idea. Especially where one side has evil stuff like salt water. I can clean off the outside of my keel condenser but designing a heat exchanger that the usual clueless operator will actually open up and clean every hundred years or so is a proposition. A coating that makes the crud less adhesive sounds interesting.

Mike,

I was thinking more about using it to inhibit corrosion. Although boiler water treatment is sound practice, getting it 100% correct 100% of the time isn't human... or me anyway. I wouldn't be using this in my monotube mind you, it would be for a future boiler.