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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Thu Jan 26, 2023 5:39 pm 

Joined: Sun Sep 05, 2004 9:48 am
Posts: 1531
Location: Byers, Colorado
Mr Boilermaker, my observations jive with yours regarding the crud stacked up at the bottom of the front flue sheet, and how hard it is to wash out. I've always admired the Chinese motive power genius who figured out that a blowdown was needed on the belly in that location. That's why I've ordered the new boiler for The Saddletanker of my Dreams with THREE BLOWDOWNS. So far as I know, this is the first time anybody in the Western Hemisphere has set up an engine this way. It damn well better work real good, and if it does, I won't be making a secret of it.

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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Fri Jan 27, 2023 9:00 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6399
Location: southeastern USA
Not all boilers have king holes as standard. I think many were introduced at steam shops by mechanics who wanted to speed up the process and eliminate a serious frustration. The last superheater flue king hole in a boiler I was inside of was top center. Makes sense, as you cut the tubes out from the bottom up and they fall into a pile at the bottom, then climb in and start passing them out from the top down. No point having the king hole buried, kind of defeats the purpose. I have seen flues and tubes that were in good enough condition to be safe ended and reused lost by being cut into short pieces and passed out through the dome if there's no king hole available.

Never say never, but my experience with copper ferrules was in the case of tube holes which were used to the extent of getting sloppy and needed them to take up around the tube to prevent overrolling. Pretty much everything we work on today shows us not the original builders specifications and practices, but those imposed in decades of hard use by the guys who kept them running. I think that's more interesting then the like new spec, which is pretty to glean from drawings and documented standards without the fun of getting your hands dirty.

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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Fri Jan 27, 2023 11:34 am 

Joined: Thu May 24, 2012 1:37 pm
Posts: 2213
I always 'ASSumed' that the copper ferrules worked in part like the 'crush washers' on some European car oil drains, and in part as a thermally-conductive material that crushes into intimate contact between tube and sheet when prossered. Do we know what 'permissible thickness' is before there start to be problems with shear in the copper?

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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Fri Jan 27, 2023 5:22 pm 

Joined: Fri Dec 27, 2019 5:57 pm
Posts: 106
Overmod wrote:
I always 'ASSumed' that the copper ferrules worked in part like the 'crush washers' on some European car oil drains, and in part as a thermally-conductive material that crushes into intimate contact between tube and sheet when prossered. Do we know what 'permissible thickness' is before there start to be problems with shear in the copper?


Define "Prossering" please.

I was shown "Prossering" rollers once; they rolled a Rounded "Ridge" just inside the flue sheet; Prossering was a step to eliminate a flue moving once rolled; I was told Prossering was rendered obsolete by welding; next time you're in a firebox or smoke box, run your finger inside of a tube; you'll feel the "rolled" portion starting immediately and extending about an inch, then the prosser, if there is one, it is a actual radius and deeper than the rolled portion.

Good video by the way; were the tubes annealed before rolling?


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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Fri Jan 27, 2023 7:20 pm 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 2561
Location: Strasburg, PA
Faller? wrote:
Good video by the way; were the tubes annealed before rolling?

I understand that new boiler tubes come from the factory annealed.


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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Sat Jan 28, 2023 12:23 pm 

Joined: Fri Dec 27, 2019 5:57 pm
Posts: 106
As informative as this video is, they could have spent a few moments describing how flues/tubes are made and which are used and the clearance between the hole and the tube O.D.


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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Sat Jan 28, 2023 9:17 pm 

Joined: Thu May 24, 2012 1:37 pm
Posts: 2213
I was t6aught that 'prossering' is the use of a tool with relatively short rollers acting within the bore of the tubesheet (see the rist tool used to roll the flue, with the offset from the tube end). If a 'locking groove' were cut into the center of the bore in the sheet, the rollers would expand the tube metal into this without also swelling the tube outside the bore on either side.

Compare this to Collins rolling, which has long cylindrical rolls extending to either side of the sheet.

Not saying that's necessarily right. If it isn't, though, I'd like to see references in 'the literature'.

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 Post subject: Re: Boiler tubes-is this a good tutorial?
PostPosted: Sun Jan 29, 2023 11:56 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6399
Location: southeastern USA
Bob, I've never seen a published standard for tube slop, but I think it is sort of a "you know it when you find it while you are installing the tubes" kind of thing. Like wear on the valve gear pins and bushings, by feel and experience.

Prossering I have run across in literature - it's rolling a grove into the tube just behind the tube sheet interface to expand it on the of the sheet. The context was an advertisement for a tube roll powered by hand held air motor that rolled, flared and Prossered at the same time. Ingenious.

Something we're not considering in this conversation is the difference in gauge of the tubes themselves.......

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