Rolled in flues?

[kvom]

I have seen a number of references to "rolled in flues" wrt boilers. Can someone explain what this means?

 

[Dan Rowe]

A tube expander is used to roll the tubes in the tube sheet. This is common for a lot of heat exchangers and some boiler designs still use the process.

http://www.tcwilson.com/heat_exchanger/expanding_kit/expander.php

Dan

 

[Maryak]

Just to expand : on Dan's post.

For this method to work you need substantial tube plate thickness, approximately equal in thickness to the tube diameter; and I would think a minimum of 1/4" thick.

Wilson make some of the best tools in the world for working with boilers and heat exchangers.

Hope this helps.

Best Regards
Bob

 

[te_gui]

In both the Steam Donkey and Steam Roller articles in Live Steam by Bill Harris, he uses 3/4" copper tubes expanded into a 1/4" or so steel tube sheet. He details an expander using rubber washers which is slipped in the tube and then a nut is tightened up squeezing and expanding the washers. I helped a friend build one and it expanded them enough to where the finish in the tube sheet holes transferred thru and showed up faintly inside the copper tube. That's a pretty good seal in my book, we never had any leakage issues anyway, so a rolloer may not be necessary.

Brian

 

[GWRdriver]

The copper tubes were the thicker-wall variety from the hardware store. They make two types of copper tubes for sale as water pipe, one has a thin wall, and one has a thicker wall.

Sorry to be pedantic but I think it's worth knowing, actually there are four common types of copper water tube in the USA - Types K, L, M, and DWV.

Type K = heaviest wall - best for coal flues, too heavy for barrels, often hard to find in stock locally.
Type L = heavy wall - best for boiler barrels, very good for flues, usually locally available in stock.
Type M = medium/thin wall - Ok for small barrels and flues in a pinch but Type L is better
Type DWV = stands for Drain/Waste/Vent, very thin wall, not good for any boiler application ever.

Examples of relative wall thickness:
4" Type K = 0.134" wall
4" Type L = 0.110" wall
4" Type M = 0.095" wall
4" Type DWV = 0.058" wall

You can see that in 4" size the wall thickness drops about .015" between types from thickest to thinnest, except for DWV which drops .076". DWV isn't intended to be pressurized at all above the force of gravity on the liquid carried.

 

[Bernd]

For those who need more info than they can use on copper tubing and it's sizes go here: http://www.copper.org/applications/plumbing/techref/cth/tables/cthindex_table.html

Click on the info you want on copper tubing.

Bernd

 

[GWRdriver]

I was in the hardware store last year, . . . . . the guy said "one is for cold water, and the other is for hot water". That sounded a little funny,

Hi Pat,
I agree with the Mueller guy, . . . nonsense. With appologies to any hardware store or Home Depot employees on the board, I never ask a hardware store or Home Depot guy WHAT I should use . . . I only ask WHERE it is. Invariably they want to know what I want to use it for and proceed to tell me "This isn't what you want, this other thing is what you want." That's about the only time I can't resist being a smart-ass and my standard line is "Well I'm with the cancer research lab over at the Univ Hospital and the three Inverse Sub-atomic Molecular Centrifugal Imploders we've built so far used that other stuff. Are you sure this is the right stuff?" POOF! They're gone!

To keep from hijacking this thread . . . KVOM, as are so many other things in live steam which amount to informed preference, tube rolling in model steam loco boilers is broken into camps. There is a roll 'em in only camp, there is a weld or silver solder (as appropriate) camp, there is a roll 'em in AND weld or silver solder (as appropriate) camp. Most of that diversity takes place in the welded steel boiler realm and all of the above can and do work, unless of course the job has been improperly or inadequately done. For copper boilers flues are practically never rolled in as there is no point. I try to make most of my boilers self-jigging, that is, they hold themselves together with a minimum of screws or rivets, and one aspect of that is making the flues a friction fit such that they stay in place during soldering. Rolling copper in copper, without silver soldering the joints, would be a waste of time due to its malleability.

 

[steamboatmodel]

I had to roll tubes on full size boilers and AC equipment, It was enough of a PITA on them, I will stick to copper boilers and silver solder.
Regards,
Gerald.

 

[xo18thfa]

Has anyone ever tried expanding tubes by using rubber washers compressed with a nut/bolt. This forces the rubber outwards, pressing the tube against the tube sheet. Bill Harris used this method widely on his work published in Live Steam magazine.

Thanks, Bob