Calling Marty Knox

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jscarmozza
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Calling Marty Knox

Post by jscarmozza » Sun Feb 02, 2020 10:39 am

Marty,
Attached is a photo of my buddy's Tom Thumb boiler, you'll notice the large bulge on the water jacket; our question is, can this section be cut out and patched, or should this boiler be heading for the scrap pile? This engine was probably running at NJLS when you were there, after my buddy bought it, he was cleaning and inspecting it and found the problem with the boiler. We'd like your opinion, thanks.
John
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image.jpeg

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Marty_Knox
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Re: Calling Marty Knox

Post by Marty_Knox » Sun Feb 02, 2020 11:03 am

First, is this copper, or steel? It's hard to tell from the picture.
Is there any way to look inside?

jscarmozza
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Re: Calling Marty Knox

Post by jscarmozza » Sun Feb 02, 2020 2:25 pm

It's a copper boiler Marty, I should have said that in the original post. Yes there are some potential access points. One of the guys at the club has an inspection scope, I think we'd be able to borrow it and fish it in to look around a little, what would we be looking for?
John

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Marty_Knox
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Re: Calling Marty Knox

Post by Marty_Knox » Sun Feb 02, 2020 2:29 pm

A buildup of scale or some other reason for the bulge. I suspect someone may have got carried away with a hydro.

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Bill Shields
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Re: Calling Marty Knox

Post by Bill Shields » Sun Feb 02, 2020 8:33 pm

easier to build a new boiler than fix that..
Too many things going on to bother listing them.

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gwrdriver
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Re: Calling Marty Knox

Post by gwrdriver » Mon Feb 03, 2020 4:57 pm

My thinking is this occurred while it was having extreme localized overheating, which could have been caused by several things, the obvious reasons (low water, too much fire, etc), and as Marty mentions a buildup of scale which prevented water from reaching the area. I doubt it was an over-zealous test as I would have expected a burst (split) in a flue, or at a joint or seam, before a tube wall deformed that much.
GWRdriver
Nashville TN

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NP317
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Re: Calling Marty Knox

Post by NP317 » Mon Feb 03, 2020 9:07 pm

My reaction on inspecting the picture was:
Scale buildup on the water side. Under pressure and heat it bulged.
Time to replace the boiler, if it was mine.
RussN

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Bill Shields
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Re: Calling Marty Knox

Post by Bill Shields » Mon Feb 03, 2020 9:42 pm

find out when you cut it apart....
Too many things going on to bother listing them.

jscarmozza
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Re: Calling Marty Knox

Post by jscarmozza » Tue Feb 04, 2020 8:33 am

Yeah, we were pretty sure the boiler was unsalvagable. Not that I'm a boiler maker, but I thought it was odd that there were no stay bolts in the water jacket area. Thanks for the replys. John

James Powell
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Re: Calling Marty Knox

Post by James Powell » Tue Feb 04, 2020 8:50 am

There don't need to be any stays in a round surface, typically...the thickness of the round surface has to be able to take the hoop stress, but there is no need for stays, which renders "Marine type" fireboxes far easier to make...

That being said, I would recommend cutting apart this boiler to figure out what went wrong. I suspect that there is scaling in between the two surfaces.

James

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Bill Shields
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Re: Calling Marty Knox

Post by Bill Shields » Tue Feb 04, 2020 10:02 am

stays in the water jacket are not needed (in any of the Tom Thumb boilers I have built).

Yes, the wrapper does have a calculable crush pressure, but it is well over 150 PSI...

put the boiler in a band saw and saw it in half
Too many things going on to bother listing them.

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Bill Shields
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Re: Calling Marty Knox

Post by Bill Shields » Tue Feb 04, 2020 6:03 pm

You never know what you will find...
bottom back mud ring area.jpg
firebox.jpg
mud ring.jpg
Too many things going on to bother listing them.

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