Water Tube Boiler Casings -Advice welcomed

[PeteThePen1]

Dear Steamboating Friends

I am in the process of getting a Lune Valley water tube boiler built. The approved drawings come from the Steam Boat Association's Boiler Library. Unfortunately, the Library is misnamed as it actually appears to hold just the pressure vessels drawings and, in most cases, not the casing drawings.

To overcome this problem I have acquired, by various means, some photos of the casings that other people have built. However, the photos are essentially of the framework. The details of how the whole shebang gets finished is mostly not shown. Using thses photos I have drawn up some thoughts of how to build a frame of pleasing shape with two opening panels for tube cleaning. My feeling is that the frame will end up as a single steel weldment of 20mm square section tube, while the two side panels will be in two parts. The fixed side panels I would envisage being bolted in place (Think boiler inspection!) while the access panels can be secured with over centre clips (think daily brushing out).

The four supports that hold the pressure vessel in place can be simple weldments, again bolted in place to allow a bit of adjustment. [Q - How much space should one allow for expansion that will occur when the fire is going well?] The same applies to the fire bar supports. The wet ashpan is simply a s/s drawer that extends beyond the rear of the casing. There is a lift up lid on the extension that provides the damper function.

The inner lining of the casing can be a single length of s/s sheet with a hole for the firebox door and one for the funnel. I would assume that it would be screwed in place with self tapping screws. The side panels can be similrly lined.

Now we come to insulation. That could be flexible or board on the sides. However, how do we stop the outer covering ending up at fire box temperature? How does one attach the outer covering over the insulation?

Your thoughts would be welcome.

Regards

Pete

Drawing 1 - Elevations with dimensions



Drawing 2 - Isometric view

[farmerden]

Hello Peter; I'll repost the pictures of the hobby boiler I bought with that other boat .It is very similar to what you want to do. It has rigid insulation about 1/2 in thick -as shown in the pics,then flat panels of tin are screwed on to cover them.The insulation appears to be in direct contact with the fire and is easily removed for boiler cleaning/inspection.The boiler came from Beckman and I don't know where to buy the insulation panels as I would like to put them in the Steam Queen as the outside of the boiler gets quite warm [well hot] and that escaping heat could be making more steam if kept inside the boiler!!

[/img]

[artemis]

Don't know if they are in your area of Canada, but E.J.Bartells is in Seattle and Portland, OR. They handle all kinds of insulating and refractory material.

[PeteThePen1]

Dear Den

Thanks for the photos and comment.

I have picked up from a back issue of Funnel that there is a material called Superwool, produced by and organisation called Thermal Ceramics. They seem to be an international company which distributes through local insulation dealers. The Funnel writer recommended Superwool 607, but commented that it costs an arm and a leg (about 25GBP per sq. ft.). The boards are apparently 500mm by 1000mm and can be up to 50mm thick. I have come across another product called Ceraboard which come in 1200 X 1000mm sheets and thicknesses up to 50mm. That seems to be about 10.5GBP per sq. ft. Both products are supposed to be good in excess of 1000 degrees C, so should be OK for us. So both should be available in Canada.

However, I am still unsure how one avoids thermal bridging when doing the outer cover. As ever, enlightenment would be welcome.

Regards

Pete

[DetroiTug]

Pete,

In direct heat transfer, seems the heat would be dissipated throughout the outer shell. One could add an insulating washer in between the shell and whatever bracketing secures the insulator board. Either way, I doubt it will be much of an issue.

-Ron

[steamboatjack]

Peter,

superwool blok 607 is the stuff available from PMR precision merseyside.
www.pmrinsulation.co.uk The blanket is probably also available here, I use it with some stainless steel mesh on the inside, see www. meshuk.co.uk 1inch sq x 1.6mm
my boiler is similar but the casing was made using two flanged end plates of 4mm steel these are load bearing for the p.vessel. the side covers outside the boiler are 16g stainless.
[img][IMG]http://i223.photobucket.com/albums/dd18 ... mg0109.jpg[/img][/img]

can't remember how to do the pics hope it turns out
regards
Jack

[farmerden]

Peter -In blowing up your drawings to a size I can read it would appear it would be difficult to cut and place the insulation around the hangers etc. Why not cover the outside of the frame with insulation and screw the exterior covering thru the insulation into the framework? Then the only thermal bridging that would occur would be thru the fasteners and that would be minimal. What do you think?? Den

[PeteThePen1]

Den

I think that is what other folks have done, but I lack any construction information. I could easily imagine using rigid board for the majority of it, with perhaps blanket across the top, given the curve.

I think my problem is to conceive of how the joints would all work so as to give a reasonable appearance from the outside. I notice that Dave's boiler in Rushforth has a vaguely similar sort of shape. Perhaps he can enlighten us (Dave, are you following this thread?).

Regards

Pete

[Johnlanark]

Hi Pete, you can see a pic of this boiler type in "Silkie" in the SBA register, built by forum member Gudmund Friis Jorgensen. "Lightning" has the original one built by Brian Smith, I owned her for several years, she is now owned by Robin Morris. I may have some photos somewhere if of interest. John

[PeteThePen1]

Peter,

My boiler is similar but the casing was made using two flanged end plates of 4mm steel these are load bearing for the p.vessel. the side covers outside the boiler are 16g stainless.


can't remember how to do the pics hope it turns out
regards
Jack

Thanks for that Jack. A uesful picture to add to my collection!

As an aside, for the pictures you only need the one set of tags to begin and end. If you copy the URL provided by PhotoBucket they will have already added the tags.

Many thanks too to you John (& Gudmund who phoned) about Silkie. I have dug up the article in Funnel and checked the pictures on the SBA Register.

Regards to all

Pete


Pete