Copper Tubing for Steam Boilers?

RayWohlfarth

I am old fashioned in my thinking and need some help on this one. I met with the installer of a steam boiler for a local brewery and he asked if he could use copper to connect the piping to the boiler. I looked at him like he had an extra nose and said condescendingly, We do not use copper on steam boilers and folded my arms to show my conviction. I have been taught ever since I was a first year apprentice that copper is not used on steam. He ignored my folded arms and began to debate me. He said copper is used for refrigeration and they have pressures higher than most boilers. He remained me R410 refrigerant has pressures almost 400 PSI. I found this article on copper.org and they say copper can be used on low and high pressure boilers, depending on how it is connected. Have I been misinformed my whole life? Thanks for your help.
Tale between my Legs...
Ray
https://www.copper.org/applications/plumbing/techcorner/cu_tube_steam_systems.html

ChrisJ

Copper not being used on steam heating boilers has absolutely nothing to do with pressure. I'm curious why you believed it did?

It's mostly about thermal expansion and swing joints. Soldered joints don't swing, they break. Copper expands and contracts quite a bit more than steel with temperature change. The threaded joints allow things to move back and forth as the piping and boiler heat and cool.

Some feel galvanic corrosion is also a concern, personally I do not when done correctly.


Also, R410A can have pressures much higher than 400 PSIG. I recall reading high pressure switches tripping at just over 600 PSI. Those systems are silver soldered or flared connections, not soft soldered. Honestly, comparing this to a steam system is a bit silly anyway.

bob_46

Chris if the center to center dimension of your risers is 18 inches the cast iron block will expand .015". A steel header 18 inches CC will expand .017". A copper header will expand .024". So the copper header expands .009" more than the block. If it's piped like your boiler and is Sil-fosed i wouldn't think it would be a problem. You could add two more 90º ells to the dropped header and have the risers enter the header about 4" apart so expansion would be almost un-measureable.

ChrisJ

bob said:

Chris if the center to center dimension of your risers is 18 inches the cast iron block will expand .015". A steel header 18 inches CC will expand .017". A copper header will expand .024". So the copper header expands .009" more than the block. If it's piped like your boiler and is Sil-fosed i wouldn't think it would be a problem. You could add two more 90º ells to the dropped header and have the risers enter the header about 4" apart so expansion would be almost un-measureable.

Hi Bob,

I don't know if it's an issue or not, but I do know most guys using copper aren't brazing it.

Also, I believe the concerns are more about the header splitting the block apart than the header and piping it self.

Ironman

I posted a similar question a couple of years ago and got the usual answers which I already knew. The problem was that no one addressed the particulars of my inquiry: Viega offers a high temp O ring that they say is fine for use on steam with their PROPRESS fittings. Since ProPress fittings have a considerable amount of "give" in them (much more than threaded), what would be the downside (if any) of using them?

I'd like a knowledgeable answer. I can't see how Viega would manufacture, recommend and sell a product for an application that wasn't right.

Someone want to help my inquiring mind?

Remember: we're talking ProPress, not sweat fittings.

ChrisJ

@Ironman

I don't think anyone here really has an answer.

I can automatically tell you guys that swear by threaded fittings aren't going to want to use ProPress no matter what, same as guys who swear by copper won't use pex.

bob_46

So each riser would have to flex .0035" in several feet, I don't know. Your draw rods are steel and the block is iron so the rods expand more than the block, do you think it will fall apart? The rubber bands probably flex.

RayWohlfarth

Thanks for the replies. I know copper will expand at a greater rate than steel. I would be hesitant about using the propress type fittings but if they work, it is a game changer because it would reduce the installation time of a boiler. I prefer threading to brazing because I can pretty much get a leak free joint with threading but my brazing skills are lacking.

I wonder if the copper would be less or more susceptible to O2 pitting or carbonic acids.

I have a friend that thinks copper is less likely to scale because the constant flexing will limit the potential for scale.

The other item about copper and steam is why there are no copper steam boilers like Laars, Raypak, etc.

Jamie Hall

The problem with the quoted dimensional changes above is that they ignore stress. Further, they ignore the little problem of fatigue in metals -- which occurs at much lower stresses than yield or failure.

There is no really good reason not to go cheap and use copper for steam piping -- provided you do two things: arrange it so that it can expand and contract freely (this means either true expansion joints or threaded (or ProPress? Hmm...) joints which can move at low stress, or piping geometries such as loops which allow the stress to dissipate in small amounts of bending over long distances) and that you support the piping so that it is not subject to vibration or bending at rigid connections -- such as at the boiler. Copper work hardens with any flexing, and then fatigues very easily.

Will you get a fatigue failure where your 3" copper riser connects to the block? Probably not -- but do you want to bet on it?

ChrisJ

" go cheap and use copper"

Have you seen copper prices lately Jamie?
We hear about empty houses having the copper wiring and piping ripped out all the time, when was the last time you heard of someone stealing all of the galvanized pipes out of a house?

bob_46

Go up in the ceiling of a supermarket with refrigerant lines a couple hundred feet long and watch them when it goes into hot gas defrost. We don't fasten them to the supports because they literally jump, go from-10ºF to 180ºF in a millisecond. I think stainless steel boilers, piping and emitters would be the hot setup.

Charlie from wmass

I think the reason we say no copper for steam is simply because most of the people that you use copper for steam don't understand steam at all. Since we have all had so many horror stories with copper pipe steam boilers we assume the piping cannot handle the conditions. The copper industry claims there is nothing wrong with using copper piping for steam systems and they say with a proper flux and solder it is rated for Steam. Also has noted viega has steam rated O-rings for their ProPress fittings. Interesting note is that Victaulic fittings now have steam rated gaskets. If proper workmanship is done and proper techniques are used copper can be used for Steam. Having said that I still cut and thread and use iron.

Charlie from wmass

And having written the above post I angered the steam gods so much my coffee just fell across the floor of my truck

Abracadabra

That'll teach you!!

ChrisJ

Charlie from wmass said:

And having written the above post I angered the steam gods so much my coffee just fell across the floor of my truck

Pfft, not like anyone would ever notice in that mess.

Charlie from wmass

I noticed because I don't have any coffee anymore.

ChrisJ

Charlie from wmass said:

I noticed because I don't have any coffee anymore.

5 second rule applies.

Fred

Does that truck look like a failed copper steam system?

ChrisJ

Fred said:

Does that truck look like a failed copper steam system?

Dumpster.

Fred

ChrisJ said:

Fred said:

Does that truck look like a failed copper steam system?

Dumpster.

You're just gonna tell everything you know, aren't you?

Jamie Hall

No coffee, Charles? Now that IS a catastrophe!

Hatterasguy said:

Jamie Hall said:

The problem with the quoted dimensional changes above is that they ignore stress. Further, they ignore the little problem of fatigue in metals -- which occurs at much lower stresses than yield or failure.

Fatigue generally requires a specific number of cycles to appear. Below a certain stress level, the fatigue life is infinite. Above that level there will be a number............5,000 cycles............10,000 cycles..........50,000 cycles.........where the component has reached the point where fatigue is a possibility.

A jet engine is a good example. Once the components in the hot section of a typical large turbofan reach 20,000 cycles, they are done. The calculated fatigue life is 60,000 cycles and the safety factor is 3:1. You CANNOT have a catastrophic failure in a jet engine or you can lose the airplane. (Que all the fellows to show photos of engine failures now..............)

Your comments on fatigue are quite true, @Hatterasguy -- up to a point. The problem with copper and fatigue (and, by the way, I don't really think it is a problem for a steam system, if expansion is allowed for) is that it work hardens, unlike the alloys used in gas turbines; indeed, one of the reasons the alloys used are the ones they are is that they don't work harden. Even something as simple as making a flare will work harden it some, and any concentrated vibration -- such as at a fitting connecting to an unsupported pipe will take it further. This is why copper is OK on flare fittings for plumbing -- there isn't much vibration -- but should never, ever be used for hydraulics on machinery (including brakes!) nor on high pressure fuel lines (I wouldn't use it for low pressures, either, but at least with low pressure you usually only get a drip and a pool fire instead of a blowtorch...) even with double flares.

And yes, an engine failure -- even a relatively benign one -- on an airplane can ruin your whole day, or at least make it much more interesting. And they do happen. And they are very frequently from fatigue...

Jamie Hall

Yeah, I saw that. I'm glad I wasn't on the 'plane. I'm even more glad that I wasn't flying the thing...

SWEI

Interesting. Those new winglets are showing up all over.

Jamie Hall

No, they fly just fine on one engine. One practices that... at some length. Of course, one has to make sure that one shuts down the ailing one, and not the good one!

And the winglets make quite a difference in drag -- if I recall correctly 5 to 10 percent for the more advanced ones. They also are nice if one is flying in trail -- the wingtip vortices are nowhere near as bad.

ChrisJ

Do they fly just fine with one engine when fully loaded?

Jamie Hall

ChrisJ said:

Do they fly just fine with one engine when fully loaded?

Yes -- except for a very few of the older light twins (the original Apaches and Cessna 310s -- neither of which will climb on one engine. Nor will a fully loaded C-46 -- but there aren't many of those left!). This is the meaning of the V1 speed which pilots compute -- V1 on takeoff is the highest speed at which you have a choice: continue the takeoff and climb away and sort things out or stop on the runway. Anything over that you're committed to fly, and can climb away. Not as fast, perhaps, but you can climb just fine. Get up in the air, sort things out, and carry on.

ChrisJ

These planes sound grossly overpowered. no?
Does this have an impact on fuel economy during normal operation?

I really have no idea, which is why I'm asking. I thought jet engines rarely failed.

JohnNY

Charlie from wmass said:

Interesting note is that Victaulic fittings now have steam rated gaskets.

When did this happen? I'm looking on the Vic website and don't see a specific product. I'd love to do my 6" and 8" headers, the 4 or 5 per year that come my way, with grooved pipe rather than threading with the universal and 300 machines.

Charlie from wmass

http://www.victaulicsteam.com/ am I the only one with google lol

JUGHNE

I hope everyone will heed the warning at the beginning of each flight: "Flown by test pilots.....do not attempt this at home"

If there were any passengers on board those flights it would become the "vomit comet".

Gordy

Hatterasguy said:

Jamie Hall said:

Yeah, I saw that. I'm glad I wasn't on the 'plane. I'm even more glad that I wasn't flying the thing...

Surprisingly, flying it is not a problem with one engine. This assumes, of course, that the catastrophic failure didn't compromise the integrity of the fuselage or the wing.

The twins have incredible power.

https://www.youtube.com/watch?v=GZRKm6PG918


https://www.youtube.com/watch?v=1XEsSRqnOwc

What I find more astounding than the maneuvers is the power plants connection to the wings, and the wing connection to the fuselage. Many cycles of stress. Much power harnessed at that engine mount.

I'm quite sure max take off weight does not allow such maneuvers.

Jamie Hall

Hatterasguy said:

Gordy said:

Hatterasguy said:

Jamie Hall said:

Yeah, I saw that. I'm glad I wasn't on the 'plane. I'm even more glad that I wasn't flying the thing...

Surprisingly, flying it is not a problem with one engine. This assumes, of course, that the catastrophic failure didn't compromise the integrity of the fuselage or the wing.

The twins have incredible power.

https://www.youtube.com/watch?v=GZRKm6PG918


https://www.youtube.com/watch?v=1XEsSRqnOwc

What I find more astounding than the maneuvers is the power plants connection to the wings, and the wing connection to the fuselage. Many cycles of stress. Much power harnessed at that engine mount.

I'm quite sure max take off weight does not allow such maneuvers.

The connection to the wing is quite critical. Under any normal operation, said connection (one at the front of the engine and one at the rear) is more than capable of handling the engine thrust (about 75K lbs on the 787 and 30K lbs on the 737). The real interesting part of the design occurs when something catastrophic occurs within the engine. The bolts act as effective shear pins to break and allow the engine to safely separate from the wing and avoid shaking the airplane to pieces. As such, they are relatively fragile and the handling of the engine/pylon interface is a bit critical during maintenance operations.

Oh, you can bet they were completely unloaded with minimum fuel. Remember, they are most definitely not rockets and they are losing speed during the entire maneuver although you cannot tell that from the videos. My guess is that they enter the base of the climb at 285 kt. (or more) and come out of the climb and level off at less than 150 kts.

@Hatterasguy -- do you remember the DC-10 accident at O'Hare a decade or two ago? That was a maintenance issue with the pylons for the wing engines, leading to fatigue cracking. Interesting. The NTSB report is long, but good reading.

JohnNY

This was a great thread for a little while.

JohnNY

"like"

jonny88

Now the ? is @JohnNY will boiler division approve propress or vic on steam.

JohnNY

Though things change quickly around here and without notification, the rule for Boiler Division inspections is that Pro-press is approved for all mechanical applications as long as the required temperatures and pressures fall into the published tolerances of the materials used. I'm going to run with this Vic thing but I will shoot a spec sheet to the Chief Inspector first for a pre-approval. I've also sent a request to my supplier today for a price list of the Vic fittings. Labor costs are high in NYC since productive hours/billable time is limited so if the Vic saves me an hour here and there I'll weigh that against the fitting costs and see what makes sense before jumping into any significant purchases.

Charlie from wmass

Won't the vic fittings be easier to disassemble in the future a significantly faster to assemble than threaded even on smaller diameters?

JohnNY

I should think so. But I'm not figuring for disassembling anything.

Dave0176

I will never use copper on a steam boiler, ever........

Charlie from wmass

@Dave0176 what about wet returns?

EzzyT

Nor would I even on wet returns.