Flaring tube ends after expanding?

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

User avatar
milwiron
Posts: 136
Joined: Sun Jun 07, 2020 1:52 pm
Location: Flanagan, IL.

Flaring tube ends after expanding?

Post by milwiron »

I've read here a number of times how expanded in-place copper tubes in a steel boiler move over time. What are people's opinions on slightly flaring the protruding tube ends after expanding to stop or slow the movement?
Edit: This is my second boiler build, my first was welded copper with silver soldered tubes. Expansion and contraction of the tubes wasn't a concern.
Denny
"Measure twice, curse once."
User avatar
ChuckHackett-844
Posts: 209
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Flaring tube ends after expanding?

Post by ChuckHackett-844 »

My understanding is that, when the tubes are properly rolled with a tube roller, they are slightly expanded on both the inside and outside of the tube sheet thereby locking them in place.
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
Owner, MiniRail Solutions, RR Signal Systems (http://www.MiniRailSolutions.com)
"By the work, One knows the workman"
Marty_Knox
Posts: 1682
Joined: Thu Jan 09, 2003 6:50 pm
Location: Michigan, USA

Re: Flaring tube ends after expanding?

Post by Marty_Knox »

I don't think it's worth it. In fact, I don't see how flaring the end will keep the tube from growing. I have tried several ways of fastening tubes - silver soldering, swedging, urethane expanders. I now use a commercial roller with lubricant and leave them as rolled. I roll them as lightly as I can to get them to seal. I do not anneal the tube beforehand. I'd rather go back and re-roll a weeping tube rather than over-roll.
The growth I've noticed doesn't seem to hurt anything.
User avatar
Bill Shields
Posts: 9086
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

Re: Flaring tube ends after expanding?

Post by Bill Shields »

No....flaring will not have any effect on this.

At best, flaring will improve the flow
Too many things going on to bother listing them.
dakine
Posts: 56
Joined: Thu Dec 24, 2020 12:03 pm
Location: Statesboro, ga

Re: Flaring tube ends after expanding?

Post by dakine »

just learning how to roll tubes - you don't anneal first? Just got a tube roller
IMG_2043.jpg
IMG_2043.jpg (16.87 KiB) Viewed 732 times
User avatar
Bill Shields
Posts: 9086
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

Re: Flaring tube ends after expanding?

Post by Bill Shields »

Some do, some do not.

As soon as you start to roll, the annealing is out the window anyway

Some say that it helps to keep from cracking tubes
Too many things going on to bother listing them.
ChooChooChris
Posts: 71
Joined: Thu Aug 11, 2022 2:01 pm

Re: Flaring tube ends after expanding?

Post by ChooChooChris »

Bill Shields wrote: Sat Feb 11, 2023 4:42 pm Some do, some do not.

As soon as you start to roll, the annealing is out the window anyway

Some say that it helps to keep from cracking tubes
I found it easier to roll after annealing.

But I also know I reduced the coppers strength by 10x (apparently 600psi crush pressure vs 6k) if data material sheets are to be believed.
-Chris Srch---- Home track Tradewinds and Atlantic Railroad
User avatar
Fender
Posts: 3022
Joined: Wed May 02, 2007 8:33 pm
Location: Chattanooga TN

Re: Flaring tube ends after expanding?

Post by Fender »

There shouldn’t be problems with cracking, unless the tubes are over-rolled, which reduces their thickness. I followed Marty’s recommendation of making the holes in the rear tube sheet the same size as the o.d. of the copper tubes, and the front sheet 0.005” oversize. Tubes were not annealed before rolling. After rolling, none leaked.
Incidentally, I have seen tubes that began to leak “heal themselves” without needing to be re-rolled. Evidently, the leak between the copper tube and the steel tube sheet became filled with rust after a few months.
Dan Watson
Chattanooga, TN
User avatar
Bill Shields
Posts: 9086
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

Re: Flaring tube ends after expanding?

Post by Bill Shields »

Absolutely true on what fender said - been there done that.

FWIW:

a seriously under rolled tube will leak like a geyser and generally require rework.

after rolling, I generally put a couple of psi air in the unit and soap it with a brush.
Too many things going on to bother listing them.
Trainsplanesandautos
Posts: 26
Joined: Sat Nov 23, 2013 6:25 pm

Re: Flaring tube ends after expanding?

Post by Trainsplanesandautos »

Not to hijack this thread but what manufacturer tube roller is best to roll copper in a steel boiler. I am going to need one and request recommendations.
User avatar
Bill Shields
Posts: 9086
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

Re: Flaring tube ends after expanding?

Post by Bill Shields »

Lest cost

I use Wilson and / or Elliott -> but hang on to $$

There are many manufacturers, but if you are in the boiler or hex business, there are the GOTO companies, and have been for decades.

You first need to know tube dimensions as well as clearance to closest obstruction.

What is the center distance from any tube to the closest anything that can get in the way of inserting the roller.

Generally the smokebox end is not as much trouble as the firebox end
Too many things going on to bother listing them.
User avatar
milwiron
Posts: 136
Joined: Sun Jun 07, 2020 1:52 pm
Location: Flanagan, IL.

Re: Flaring tube ends after expanding?

Post by milwiron »

Something to consider if space is tight.
Pictured below is my commercial roller and my homemade roller, both fit 1/2" K copper tubing.
The home built roller doesn't have many clearance problems. They seem to work equally well.
Rollers.jpg
Rollers.jpg (87.35 KiB) Viewed 505 times
"Measure twice, curse once."
Post Reply