Watertube boiler casing lining

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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marinesteam
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Watertube boiler casing lining

Post by marinesteam » Fri Jul 27, 2018 1:12 am

Been taking a rough pass on CAD for the design of the casing for my two drum water tube boiler. Searching through the forum and Google it appears that the majority of the casing that actually show enough detail to make a determination that the casings are lined with steel sheet with the insulation sandwiched between the inner sheet and outer material of the casing.

Is the consensus of the forum to have an inner liner protecting the ceramic insulation?

Also, how much should one worry about the heat transferring from the inner liner to the outer sheeting though fasteners and support tabs? Is it a non issue or do I need to go through extraordinary effort to build a casing that keeps the inner and outer from having any structure between them that may transfer heat?

Thanks

Ken
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barts
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Re: Watertube boiler casing lining

Post by barts » Fri Jul 27, 2018 1:43 am

I used stainless sheet (thin - 22 gauge or so) for the inner sheet. The firebox itself gets insulated w/ something serious like castable refractory if has fire hitting it directly. I used an inner and outer frame to fasten the inner and outer casings; no real problem w/ heat transfer. Again, if the flames hit the inner casing, you'll have problems w/ heat.

The silica fiber stuff is pretty fragile after some heat cycles - I think it should be covered to last.

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Re: Watertube boiler casing lining

Post by Mike Cole » Fri Jul 27, 2018 5:46 pm

I am used a stainless steel mesh rather than a solid sheet, it is holding up well , at a guess around 3 to 4 mm hole size. Do not worry about heat transfer via fixings. and I have used fire bricks for the lower part where the coal bed is.
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Re: Watertube boiler casing lining

Post by TriangleTom » Fri Jul 27, 2018 9:35 pm

What are you using as insulation?
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Re: Watertube boiler casing lining

Post by barts » Fri Jul 27, 2018 10:24 pm

I used 1" thick FiberFrax blanket. Fiberglas would also work where it doesn't get too hot. Firebox is made from castable refractory on the inside, plus Fiberfrax.

Some pictures pre-castable refractory here: http://www.smaalders.net/bart/boiler.html

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Re: Watertube boiler casing lining

Post by marinesteam » Fri Jul 27, 2018 11:45 pm

Thanks for the feedback guys.

I was thinking of using Superwool HT board or similar http://www.morganthermalceramics.com/me ... boards.pdf

Ken
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Re: Watertube boiler casing lining

Post by barts » Mon Jul 30, 2018 4:21 am

This will prob. work just fine. Keep in mind that for trailerable boats, the most difficult environment may well be traveling over rutted roads rather than steaming around. I once tried lightweight firebrick - great insulator, but could not deal with shock loads from our admittedly rough roads. Otter was traveling 3000+ miles a year on a trailer, and we were steaming perhaps 40...

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Re: Watertube boiler casing lining

Post by marinesteam » Mon Jul 30, 2018 4:06 pm

Bart,

That's a good point, one I hadn't thought about. I'll look into the durability of the board, but will consider blanket now as well.

Thanks

Ken
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Re: Watertube boiler casing lining

Post by malcolmd » Tue Jul 31, 2018 4:39 pm

I used a 1 inch ceramic fibre board from vitcas.

https://shop.vitcas.com/ceramic-fibre-b ... board.html

You can cut it with wood working tools or serrated knife. No inner steel liner.

See blog for more details on insulation and casing

https://sy-befur.co.uk/2017/07/04/boile ... nd-funnel/
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Re: Watertube boiler casing lining

Post by marinesteam » Tue Jul 31, 2018 6:13 pm

Malcom,

IIRC your firing with oil. I am leaning toward solid fuel. Do you think the insulation would hold up in the "firebox" area? I suppose I could line only the box area with firebrick or steel.

Thanks

Ken
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