copper pipe

thfurnitureguy_4

What grade of pipe should be used for Iron pipped returnes? If copper pipe were to be used for a steam return what grade should I use? Are there different grades of fittings? Thanks T.

oil-2-4-6-gas

if its a full wet return you will ok with L-copper and make sure your fittings are for pressure and not dwv--it would be best to braze your joints but a good silver,or 95/5 solder will do

thfurnitureguy_4

Thanks, What are the grades of copper? Is L the thickest or what?

WPH2205

No, type K copper has the thickest wall and is generally used for water service piping (underground). Type L is for water supply piping above ground and most uses within a building. Type M has the thinnest wall and is used for hydronic heating.

Ken_8

I suggest,

you avoid copper. The mild acids formed in all steam returns will be better serve with steel. It is half the price as well. Use cast iron fittings. They too are less.

Anytime something is better and less... we get a "home run."

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thfurnitureguy_2

Ken Thanks for the copper info. I have heard many diferent thoughts on copper. I am considering copper because of the poor shape my Iron pipe is in after 20 years or so. I have no idea what kind of maintence was or was not done that would cause the rust. I am the recent owner of this older building. Am I expecting too much? What is the expected life of an Iron Return? I wish someone could give me the life of a copper return. Any ideas? so far all I am hearing is a good and bad about both materials I have rusty Iron and its not that old. I was going to try copper. Your experiance is valued thanks for your responce

Ken_8

TFG,

A wild guess suggests 'L' copper might last ~10 years in a not-so-well maintained steam system and cost about three times the cost of standard schedule 40 steel pipe. The steel pipe in a not-so-well maintained system might last ~25 years.

I do have well maintained steam systems out there that have original steel wet retruns that are well over 75 years old however. Three factors come into play: the "nature" of the water; the nature of the maintenance; and the nature of the operating parameters. Over time, all three can cahnge dramatically. Water treatment is a great way to mitigate all three potential problems.

There are no set rules. Common sense and experience are the only sources of longevity. I've seen many promote the use of chemicals - without knowing the system has leaks, bad feedwater that turns the chemicals into compounds that cannot be easily checked, etc.

Let us know how you make out.

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michael_15

metals

In any event, iron will corrode much faster than steel and copper in the presence of light acid like the carbonic acid which will form in steam systems.

Steel tends to form a protective, semi-acid resistant coating which protects the iron inside from corrosion.

Copper is resistant to most non-oxidizing acids as well as being resistant to galvanic corrosion, which makes it popular for carrying things like, say, water. You don't come across oxidizing acids in everyday work. Copper, however, is quite vulnerable to nitrogen/amine-based compounds such as ammonia.

Iron, however, is not only more susceptible to galvanic corrosion but is also easily eaten up by acid.

If you're interested in trying, take a hunk of copper, iron, and steel and drop them into a beaker (bucket, whatever) of hydrochloric acid. I think you can buy the stuff under the name muriatic acid.

If you like defacing money, you can take a file and file away a tiny notch in a penny and drop that into the acid, too. The outside of the penny is copper-coated and hence resistant to acid, but the inside I believe is brass/zinc, which is easily corroded by acid. After a while, you'll have a hollow penny, which, if you're sufficiently weird, is great for pranks.

-Michael

Fred Harwood

Copper

A nicked penny exposes the sacrifical zinc, which dunked in even a mild acid makes a battery that consumes the zinc, completely.

Weezbo

there are a few other ratings of copper pipe......

one for example is type O itis used in scientific experimental labs...just thought id chuck that in *~/:)

ScottMP

And for you non-plumbers

The thinnest is rated DWV.

Drain, Waste and Vent. Color coded yellow.

Scott

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Ken_8

Whatever you do...

Don't smoke when doing this experiment!

The hydrogen gas produced will rock your world and you'll look awefully funny with no eyebrows.

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Weezbo

S milne , i wonder about brass air fittings,do you have any

leeds on a supplier of formed brass Y's .....heres why, the carpenters busted a part off the bottom of an ingersol rand and no one sells certain yellow brass fittings of that configuration or "Square "female to male fittings here..the dealer of the equipment doesnt even show the part that was broken ...i looked plumbing companies automotive and am thinking of Hydraulic fittings , now...the things that i am looking for are 1/2" y, 1/2" X6port diverter manifold ....i am now wondering if Schrader ...BRB...........:( i just having zero luck with this....

thfurnitureguy_4

copper

Where is the H2CO4 comming from (if I remember the formula for carbonic acid) if a boiler is little more than a good sized still, isn't the water in the returns distilled Water. One step away from prety darn pure and clean? I would expect leaching rust but where is the acid formed? I would expect the water left behind in the boiler to be a sorce for concentrated salts and acids.

thfurnitureguy_4

Check a company that sells air paint spray equipment, Binks or DeVillbiss they sould have a bunch of these 1/4npt brass fittings.

michael_15

the carbonic acid

(I'm just restarting this thread on the left in response to the latest message)

The carbonic acid occurs and regenerates naturally in steam systems (this won't apply for hot water) from atmospheric carbon dioxide as follows:

H₂O + CO₂ --> H₂CO₃ (carbonic acid)

This is why normal rainwater is slightly acidic. "Acid Rain" that they teach kids about in school is such because there are nasty things like SO₃ in the atmosphere. Add SO₃ to H₂O and you get sulfuric acid, which is not your friend and a whole lot stronger than carbonic acid.

The hydrogen gas that Ken speaks of comes from the acid hydrolysis (dissolving) of metal. For a simplified example:

2 H₂CO₃ --> 2 H⁺ + 2 HCO₃^-

Zinc(solid) + 2 H⁺ --> Zn²⁺ (dissolved!) + H₂ (gas)

If you're enterprising, you can take collect the hydrogen and make a small explosive.

-Michael

thfurnitureguy_4

Now if I had kept after the books rather than the girls I would have known that. I still love this stuff. The $2000. Question, Paper or plastic. I mean copper or Iron pipe for a steam return? The goal here is to never need to know that I have a steam return (with the exception of a yearly flush). What ever I do I want it to last.

Tony Conner_2

In Big...

...industrial systems, the bulk of the carbonic acid is due to natural alkalinity in the make-up water. Under boiler conditions, this alkalinity breaks down into CO2, and is carried out of the boiler with the steam. The CO2 dissolves in the condensate, and can make it about the same pH as soda pop. A lot of plants with problems of this nature install dealkalizers (they look similar to softeners) that will take care of about 85% of the problem. Corrosion from stemming from this problem will typically show up as "grooving" along the bottom half of horizontal return lines. If you look down the pipe, the top half is full-wall, and the bottom half (from about 3 o'clock to 9 o'clock) will be far thinner, mayube to the point of leaking. If you've got a line full of rusty carbuncles with localized pitting under them, then that's probably oxygen corrosion.

In big plants, nobody who knows anything about water treatment chemistry installs ANY copper piping in their condensate return system. If a situation develops where the copper corrodes or erodes, copper can find it's way back to the boiler, where it will plate-out, and form a galvanic cell. The resulting corrosion looks very similar to oxygen pitting.

Copper return lines do not nearly always cause a problem, but when they do, it's bad news back at the boiler.

michael_15

i'd say

neither copper nor iron, go for the steel.

Or heck, you can just not have a wet return. I'm not sure what the gurus here think about that (I certainly wouldn't take my advice on it, that's for sure), but you could just bring the pipes back over the waterline. Since your main vent will be located just after/at the last radiator takeoff, you won't need to worry about filling the return piping with steam. The return would just need to drop below the waterline right before it hits the boiler, so you'd only have a few feet of piping which holds standing water.

In theory (though I doubt this applies in practice), this would also lengthen your pressure cycling since there will be a buffer zone of compressible air in the return piping.

-Michael

Tony Conner_2

From The \"Betz Handbook...

...Of Industrial Water Conditioning", 9th edition. For those not heavily into the actual chain of events, chemistry-wise, the photos do a great job of illustrating the different types of corrosion.