Dear RYPN'ers;

We have to run some lubricator tubing; 1/2" OD copper tubing. I was going to order some thick walled tubing (wall thickness 0.65 thou), but I was wondering about the fittings.

Where the copper tube fits the lubricator is no problem (silver soldered connectors), but there are flare fittings on the steam lines, and probably will be on the new manifold, once it is complete.

Questions:

1) 1/2" OD copper tube (3/8" size) - should it be attached to a flare fitting? Is this tube too thick?

2) What wall thickness have you used? I did the calculations on annealed tube, the thick wall would give us a safety factor of 12:1, but I'm really concerned about the flare fittings possibly failing.

Failing 1) above, what kind of connectors would you suggest in this application?

We might as well do this right - we only run our auxilliary crane at 100psi, but, 100psi of steam is still dangerous.

Thanks;

John Stewart
Ottawa, Canada.



freewrl-1@rogers.com

We use 3/8 OD x .065 wall copper tubing exclusively in our lubricator plumbing with flare fittings throughout. This has been quite satisfactory for us for many years, working against terminal checks set at 300 PSI.

The secret to making a long lived flare fitting connection is to anneal the tubing before flaring, anneal it again after flaring, and assemble the joint with antiseize on the back side of the flare where the nut has to spin on the tube, but with no antiseize on the sealing seat of the flare.

Flare fittings fail most often in high vibration locations such as on a cross compound air compressor. Properly supporting the tubing in these situations is vital to reliable operation.

Strasburg Rail Road
kelly@strasburgrailroad.com

> The secret to making a long lived flare
> fitting connection is to anneal the tubing
> before flaring, anneal it again after
> flaring, and assemble the joint with
> antiseize on the back side of the flare
> where the nut has to spin on the tube, but
> with no antiseize on the sealing seat of the
> flare.

What is your annealing procedure?

mike211@yknet.ca

> What is your annealing procedure?

Heat the last inch or two of the tube with a torch until dull red, then quench in water, or let cool of its own accord.


Strasburg Rail Road
kelly@strasburgrailroad.com

> We use 3/8 OD x .065 wall copper tubing exclusively in our lubricator plumbing with flare fittings throughout.

No doubt Type M tubing. But the flare fittings are not as safe as ferrule fittings. I have never seen flare fittings used on a locomotive "pre-restoration." Not even on brake system gauge lines.

Hydrostatic lubricator delivery lines are often 5/8" od. The fittings are usually unique: copper to 3/8" iron pipe. Have a machinist copy the existing fittings/adaptors.

It is true that the silver solder locus of the Detroit adaptors has a slight flare. I once found some near copies of the Detroit adaptors in a Navy salvage yard. They were unmarked but could have been a commercial fitting.

Sorry, but I disagree with the statement about flare fittings not being as safe as ferrule fittings. In my 30 plus years of experience, I have had a multitude of ferrule fittings fail, but only one flare fitting fail. Why do they still use flare fittings(doulble flare) in automobile brake lines rather than a ferulled fitting, you guessed it, because of the low incidence of failure. There are many high quality compression type fittings on the market if you chose to go that route, do not use the plain jane hardware store version for steam or air brake applications.

A quality flare does take some time to produce but if done right it will out perform a ferruled fitting.
My 2 cents
Mike

mtillger@adelphia.net

> Why do they still use flare
> fittings(doulble flare) in automobile brake
> lines rather than a ferulled fitting, you
> guessed it, because of the low incidence of
> failure.

Also consider the fact that copper tube is NOT used in vehicles or aircraft. Any amount of vibration causes it to work harden and crack. Soft steel alloys are used specifically because of this problem.
Mike

mike211@yknet.ca

As Kelly states in another answer; heat to dull red then let cool. (air or water; doesn't matter). Silver soldering it will, of course, anneal it.

Copper is really neat to work with; I have made (almost - one not quite complete) 4 model locomotive boilers out of copper; so I'm getting quite good at annealing it. ;-)

I'd suggest to anyone that they take some copper (thin strip of sheet preferably), anneal it, then bend it, and feel it harden. A simple experiment, but one that you will learn lots from. It goes from "putty" to "iron" incredibly quick.

John Stewart.

> What is your annealing procedure?


freewrl-1@rogers.com

> Also consider the fact that copper tube is
> NOT used in vehicles or aircraft. Any amount
> of vibration causes it to work harden and
> crack. Soft steel alloys are used
> specifically because of this problem.
> Mike

The old N&W pipefitters I used to work with said that part of every steam overhaul including pulling all the copper lube lines off, boiling them in a caustic tank to remove gunk from the inside, and annealing them in a furnace to reverse the work hardening.

I wonder if soft steel wouldn't be a better material to use.

Hugh


The Ultimate Steam Page
whodom2001@yahoo.com

The 3/8 OD x .065 wall copper tubing that we use is actually at the other end of the spectrum from Type M tubing, since Type M is thin wall (.025) tubing for low pressure service, and what we use is much thicker than Type K (.035 wall).

I agree that flare fittings are not “historically accurate” for steam locomotives, I doubt they even existed during the “steam era”. Where flare fittings shine is when there is a failure, they are very quick to repair. In our operation, we only have a 10 minute window between trips to make any minor repairs during the day. If there is a failure (always on a cross compound air compressor), a mechanic equipped with flaring tools and a propane torch can re-flare, and re-assemble the line in question within that 10 minute window, and only loose about 1/8" of length in the line.

Ferrule fittings are also quick to repair in the case of a broken line, but are libel to loose 1/2" of length until a new ferrule is installed after the break. Depending on how much “slack” can be “stolen” in the line, that can be a real problem.

We have also had traditional silver soldered unions fail in this service, and of course are impossible to repair between trains. When that happens, what to do? Install a flare fitting, and the train wonÂ’t be delayed more than a few minutes.

With the virtual cornucopia of copper tube fittings that are available, each with their own advantages, and disadvantages, the only “right” answer to this question is “to each, his own”.


Strasburg Rail Road
kelly@strasburgrailroad.com

> I agree that flare fittings are not
> “historically accurate” for steam
> locomotives, I doubt they even existed
> during the “steam era”.

Au contrare; there were a number of large locomotives built late in the steam erea that had flare fittings, particularly on lubricator lines.