Piping

AlfredRose

Am new to the group. Asking if it would be OK to use galvanized pipe after last riser on one pipe parallel wet return. Or for the whole system if I have the energy to do so. This to reduce rust accumulation in system and boiler.

Jamie Hall

steam or hot water? In the case of steam, black iron pipe is preferable. In the case of hot water, copper or, in newer lower temperature systems, oxygen barrier PEX.

Galvanized steel rusts. Badly. Quickly.

ChrisJ

Jamie Hall said:

steam or hot water? In the case of steam, black iron pipe is preferable. In the case of hot water, copper or, in newer lower temperature systems, oxygen barrier PEX.

Galvanized steel rusts. Badly. Quickly.

It does?
Isn't the entire reason for the zinc is for protection of the steel?
Isn't modern "black iron" pipe just steel pipe with a black protective coating?

Most places you're allowed to use galv pipe for gas piping outside but if it's "black iron" it needs to be painted. Some areas require glav pipe outside for gas.

Jamie Hall

All I can say about black iron -- old -- and galvanized steel for piping is that I have had to replace every inch of galvanized steel pipe in the properties I maintain because it rusted shut or nearly so on the inside, making it somewhat useless as a pipe... whereas the black iron piping in the same properties has been in place for over a century, and the only leaks I've had were where it was in contact with mortar or in one place where a threaded joint developed a drip.

ChrisJ

Jamie Hall said:

All I can say about black iron -- old -- and galvanized steel for piping is that I have had to replace every inch of galvanized steel pipe in the properties I maintain because it rusted shut or nearly so on the inside, making it somewhat useless as a pipe... whereas the black iron piping in the same properties has been in place for over a century, and the only leaks I've had were where it was in contact with mortar or in one place where a threaded joint developed a drip.

I've never seen black iron used for potable water?
Or any kind of water?

As far as I know, all black iron and galvanized piping, at least in a very long time has all been steel. Obviously a pipe clogging up due to minerals and rust isn't because of the zinc.

@AlfredRose Honestly, I'd be considering copper. Can you share some pictures and more information about the system and application?

AlfredRose

The system is ancient, had radiators removed, asbestos falling off everywhere. Just turned 72, worked in a plumbing supply house for ten years back in the seventies/eighties, love a challenge almost as much as I love "The Lost Art Of Steam Heating". Have read and re read and continue to read for about three months now. Most of the piping is in a crawl space that I haven't got into yet. Galvanized pipe is still black steel where the threads are concerned. Am not sure about what effects carbolic acid may have on it. Do not know how to post pictures, but I must say I am VERY happy to now be a part of this forum and here your comments ! Am certain the boiler is oversized, just don't know how much yet until I can get into the crawl space and look. The building is an American Legion Hall that I have just joined. I am not a licensed heating contractor and as such I will not touch any of the controls on the boiler. The piping I have no qualms in reworking as some of it is completely contrary to what's in the book. Will be consulting a very rare person who is licensed and knows steam before I proceed. Thank you all so very much for your interest and comments.

EBEBRATT-Ed

It's steam I would use black pipe.

Some use schedule 80 for condensate in commercial buildings but it is unnecessary if the make-up water is kept to a minimum.

Jamie Hall

Comment on the corrosion concern. First, and perhaps most important, is that in steam use, even on wet returns, corrosion is almost negligible. There is no oxygen in the steam, once the system is steaming at all, and the condensate is, of course, distilled water -- no oxygen, no salts. On top of that, the ability to use malleable (or ductile, if you don't mind the cost) iron fittings is a tremendous advantage.

Second, galvanized iron pipe does rust, but differently. Unless the galvanizing is of high quality and not damaged, however, the rusting often takes the form of blisters under the zinc, which tend to block flow and the zinc may glake off. Personally, with the availability of copper (or PEX at lower temperatures) I can't see much of a current use for it.

mattmia2

i think this debate has been had before, but about 3 years ago i cut out some galvanized cold water pipe from my mom's house from 1957 and it had little rust on the inside. the hot water pipe was all replaced 25 years ago because it was heavily rusted on the inside and had developed a couple leaks. it degrades much faster if it is hot. i have heard that the reaction reverses at high temps but don't have any proof of that.

ChrisJ

Jamie Hall said:

Comment on the corrosion concern. First, and perhaps most important, is that in steam use, even on wet returns, corrosion is almost negligible. There is no oxygen in the steam, once the system is steaming at all, and the condensate is, of course, distilled water -- no oxygen, no salts. On top of that, the ability to use malleable (or ductile, if you don't mind the cost) iron fittings is a tremendous advantage. Second, galvanized iron pipe does rust, but differently. Unless the galvanizing is of high quality and not damaged, however, the rusting often takes the form of blisters under the zinc, which tend to block flow and the zinc may glake off. Personally, with the availability of copper (or PEX at lower temperatures) I can't see much of a current use for it.

Jamie please correct me if I'm wrong but my understanding is galvanized steel in general is better than painted because it doesn't have to be perfect in order for the sacrificial zinc to work.

Even if there's missing zinc the surrendering zinc will still perform it's function no?

mattmia2

ChrisJ said:

I've never seen black iron used for potable water?
Or any kind of water?

I have seen black iron used for potable water that was probably from the 20's or 30's.

AlfredRose

Will most likely use black pipe. By the time it rusts out I will probably exploring at the far end of the galaxy. Upon closer inspection I think I see some galv in the crawl space, won't know till I get there. Copper would sure be easier to work with but it will be a job just to get the people to pay for the insulation. Any suggestions as to where I may purchase 1" thick fiberglass insulation and fittings on line ? Have been using "Buy Insulation ". The three foot lengths cost extra to ship. Thanx again for your thoughts.

Jamie Hall

That hot vs. cold rusting with galvanized has been my experience, too, @mattmia2 .. And no, I don't know why. And yes, @ChrisJ , the galvanizing zinc should protect the bright steel from corrosion if any is exposed. Exactly what it is supposed to do. Why it doesn't sometimes is over my pay grade.

I'm wondering if the black iron pipe which folks used years ago may really have been malleable or ductile iron and not black oxidized steel. Again just from experience and nothing else I have noted that iron -- cast or malleable -- just rusts a little and then lasts and lasts and lasts, while steel rusts quickly (except for such oddities as Corten), even when it is galvanized.

ethicalpaul

Maybe I'm confusing my terms, but isn't the 100+ year old main pipe on my steam system made of steel? It isn't rusting quickly

ChrisJ

ethicalpaul said:

Maybe I'm confusing my terms, but isn't the 100+ year old main pipe on my steam system made of steel? It isn't rusting quickly

Don't know.
There's a chance 100 years ago it actually was iron pipe.

But, the black iron I've added to my steam system doesn't seem to be doing much in the past 10 years as far as rust or corrosion.

ethicalpaul

So, sorry for being ignorant but what would be the difference (in residential steam systems) between "iron pipe" that Jamie is mentioning and what I would call "steel pipe" or "black pipe" (seems to just be painted black) that are sold today? I can't tell the difference. My old main pipe seems to be just like modern pipe (steel), but not painted.

We're not talking about cast iron pipe, are we? I know what that is like (at least in my house). Much thicker walls and not threaded.

ChrisJ

ethicalpaul said:

So, sorry for being ignorant but what would be the difference (in residential steam systems) between "iron pipe" that Jamie is mentioning and what I would call "steel pipe" or "black pipe" (seems to just be painted black) that are sold today? I can't tell the difference. My old main pipe seems to be just like modern pipe (steel), but not painted.

We're not talking about cast iron pipe, are we? I know what that is like (at least in my house). Much thicker walls and not threaded.

Steel and iron aren't the same thing.

I believe black iron pipe was actually made of iron at one point. I do not believe that to be the case anymore.

ethicalpaul

I know they are different things. But I keep hearing "iron pipe" and "steel pipe" but to my knowledge, all the pipe I have in my steam system, and all the NPT pipe and nipples I can buy today are made of steel.

So I'm trying to figure out if this "black iron pipe" that Jamie and others are talking about is actually something different than that or if it's kind of an incorrect name for what is actually steel pipe that is painted black (that I see available for purchase today for gas and steam applications)

Jamie Hall

ChrisJ said:

ethicalpaul said:

So, sorry for being ignorant but what would be the difference (in residential steam systems) between "iron pipe" that Jamie is mentioning and what I would call "steel pipe" or "black pipe" (seems to just be painted black) that are sold today? I can't tell the difference. My old main pipe seems to be just like modern pipe (steel), but not painted.

We're not talking about cast iron pipe, are we? I know what that is like (at least in my house). Much thicker walls and not threaded.

Steel and iron aren't the same thing.

I believe black iron pipe was actually made of iron at one point. I do not believe that to be the case anymore.

I think we're getting somewhere here. Anyone up for taking a sample of old iron pipe and new black "iron" pipe (which may well just be painted steel) and getting them analysed? Both of course are based on iron -- but the grain structure and alloying are very different. Both are magnetic, so that doesn't help....

Larry Weingarten

Hi, We may be getting into the difference between cast and forged. Cast allows crystalline growth in the metal, while forged does not. Also, considering @Jamie Hall 's comment on alloying, I found this: "The primary difference between iron and steel is that the former is a metal, whereas the latter is an alloy. Iron is simply a metal element that occurs naturally on Earth. In comparison, steel is a man-made alloy that's made by mixing iron and carbon together."

Yours, Larry

ethicalpaul

My steam piping is definitely not cast. Does anyone have steam pipes (not fittings) that are cast?

If we can rule that out, then yeah I'm interested in knowing if there are actually iron pipes (again, not fittings, I know I have some of those) in any of our steam systems. Thanks!

As for analysis, I think all my pipes are steel, so I can't help there!

Maybe this is good info? https://metalexponents.com/blog/choosing-ductile-iron-steel-pipes/

mattmia2

I think either @retiredguy or @Steamhead mentioned using a different type of iron pipe in the distant past in a recent thread.

WMno57

Iron pipes are used in DWV (drain, waste, and vent) and municipal water and sewer. They are not threaded, and are joined with lead or gaskets. Iron pipe doesn't even come in the same sizes as steel pipe.
https://en.wikipedia.org/wiki/Cast_iron_pipe
https://en.wikipedia.org/wiki/Ductile_iron_pipe
The threaded black pipes used in hydronic heating (steam and hot water) are ALL STEEL. I don't care how old they are. ITS ALL STEEL. OK, maybe one of our Pros knows of some exception to this where some oddball home built in the 1850s had iron pipes for steam. I doubt it, but I could be wrong.
Fittings, even today, could be iron or steel.

Jamie Hall

I wonder how many hundred? thousand? varieties of metal materials there are out there which are, depending on variations in alloying elements and heat treating and fabrication methods are varations on "iron" or "steel". To say that (cast or forged) are not threaded is just wrong -- there is no reason why they can't be, though I'd hasten to agree that hub type DWV cast iron piping (and fittings) is just exactly that -- cast iron. It's by no means the only type of iron piping. Also, I would agree that in general the currently available iron or iron alloy pipes available are actually better classed as steel or steel alloys.

As noted in various references (here is a very useful -- and thorough -- one: https://material-properties.org/steel-vs-iron-comparison-pros-and-cons/ ), the difference between iron -- whether natural or worked -- and steel is that steels contain very little carbon, while iron does contain carbon (the percentage in steels determines whether one is referring to "mild steel" -- low carbon -- up to ultra high carbon steels) and almost always, though not always, a variety of other alloying elements, such as chromium, nickel and manganese. It is not possible on visual examination to between low alloy steel and iron. Hardness is a useful tool, if one has access to a Brinell or Rockwell hardness test.

All varieties of iron/steel will corrode ("rust") in the presence of oxygen. How fast they do so, and what the effects are, depend on a wide range of external environmental conditions, both natural (the pH and ionic species present in any water, as well as the availability of oxygen, for instance) and artificial (such as the presence of zinc coatings or zinc anodes, or impressed cathodic protection systems). Some steel alloys form protective oxide coatings which adhere well to the base metal, such as stainless steels or the "Corten" group of weathering steels, though the effectiveness of those coatings varies widely and the actual choice of alloy -- particularly in the stainless steel groups -- may be critical.

ethicalpaul

Yes, it is clear to everyone that both iron and steel exist, but in steam piping we can all agree it's all steel so I don't have to wonder anymore?

ChrisJ

ethicalpaul said:

Yes, it is clear to everyone that both iron and steel exist, but in steam piping we can all agree it's all steel so I don't have to wonder anymore?

I don't think I've ever wondered until this thread.
Didn't really care.

The one subject I'm pretty sure on is cast iron vs malleable fittings on steam systems. It flat out doesn't matter unless you plan on shattering them for removal. I personally use a grinder and a cutoff wheel or a sawzall.

EBEBRATT-Ed

@Jamie Hall
Years ago when I worked at an oil company, we piped a lot of underground oil tanks for #6 & #4 oil. My boss wanted me to go to the supply house to get some pipe. I said "we have pipe on the pipe rack" he said yeah that's "wrought Iron pipe" we use that for underground when the engineer specs it. It doesn't rust as quick. The wrought iron pipe looked the same, but it had a stripe of red paint on it.

JUGHNE

If some steam pipe was actual cast iron and one had a piece of it removed, could you shatter and crack it like soil pipe?

ChrisJ

JUGHNE said:

If some steam pipe was actual cast iron and one had a piece of it removed, could you shatter and crack it like soil pipe?

Yes but no one said steam pipe was cast iron.

WMno57

https://www.reliance-foundry.com/blog/difference-cast-iron-wrought

Jamie Hall

Good article. Thank you. Just for laughs, among other "home defence" items lying around the place, we have two swords (one claymore from about 1740 or so, one British officer's short sword from about 1800) -- of forged wrought iron. Not steel. Not ductile iron. Not cast iron. Very flexible. Take a fantastic edge -- and hold it. Very little rust. But that is what real swords were made out of.

And yes, @EBEBRATT-Ed -- I remember specifying wrought iron for underground piping!

Mad Dog_2

"When I was back there in seminary school...." (Jim Morrison The Soft Parade). 530am joke!   When I started in mid 1980s as an Apprentice cutting out The old DWV (drainage, waste, and Vent piping) for renovations, NOT LEAKS,  in old  Manhattan buildings, it was VERY hard to cut. My Mechanics told me it Was called The Durham System and it wasn't just plain galvanized steel, it was Wrought Iron! Installed in the 10, 20s, 30s.  Additionally, the Galvanized domestic water (Crotons as we call them in the 5 Boros) piping that I cut out in very old homes in College Point (Remember the German Baroness, Eva Von something or other who lived in that Mansion?) and Flushing Queens in the mid 1980s was installed sometime in the Second half of the 1800s and was still in good shape over a Hundred years later!  The Hot would have the carbuncles on the inside but still had like 90% flow capacity. Me thinks that Was Galvanized wrought Iron too!  Mad Dog 🐕 

ChrisJ

lkstdl

AlfredRose said:

 Any suggestions as to where I may purchase 1" thick fiberglass insulation and fittings on line ? Have been using "Buy Insulation ". The three foot lengths cost extra to ship. Thanx again for your thoughts.

Call around to some distributors. We use SPI. 

There are products that can be bought cheaper from online stores; in my experience insulation isn't one of them.

AlfredRose

Am not sure what SPI is. Has been almost 40 years since I worked at the plumbing supply house. They had just dropped asbestos insulation, ( still had the cement in bags ), and switched to fiberglass. Will try Google and or Amazon. Thanx for the tip.

BruceLundeen

Good information about pipe. But nobody said something that I don't do but see all the time. Don't be putting a quick-fix copper pipe into a steam or hot water system. We think that brings down the whole system by causing electrolytic corrosion.

JUGHNE

For me the online insulation was less costly but the freight made it not so.

I got a lot locally (for me that is 200 miles away) and they shipped it via "Pony Express".

Not common carrier.

mattmia2

BruceLundeen said:

Good information about pipe. But nobody said something that I don't do but see all the time. Don't be putting a quick-fix copper pipe into a steam or hot water system. We think that brings down the whole system by causing electrolytic corrosion.

In some parts of a steam system it can be a problem. In a closed hot water heating system it is not.

ChrisJ

BruceLundeen said:

Good information about pipe. But nobody said something that I don't do but see all the time. Don't be putting a quick-fix copper pipe into a steam or hot water system. We think that brings down the whole system by causing electrolytic corrosion.

I don't think it brings the whole system down.
In fact, I don't think it causes much of a problem period.

Jamie Hall

BruceLundeen said:

Good information about pipe. But nobody said something that I don't do but see all the time. Don't be putting a quick-fix copper pipe into a steam or hot water system. We think that brings down the whole system by causing electrolytic corrosion.

There are places where it's no problem -- I wouldn't hesitate to use copper on a wet return, for instance. Usually the problem with copper on steam is not allowing for expansion, rather than corrosion problems.

AlfredRose

One pipe steam, parallel flow, wet return. A radiator was replaced with 2" steel fin radiation. 3/4" copper installed at the end of steel fin opposite of steam inlet. The copper runs to the wet return with a main vent installed at the end where it feeds to the wet return - no regular radiator vent installed. There is steel fin in another area that has a regular angle vent on the end. Neither setup heats adequately that I can see, at least not as well as a radiator would. Wish to purchase new radiators to replace the steel fin. Two 2" mains going to one radiator and one steel fin each.
From what I can see there are at least three 1" risers that have caps on them. Will get boiler specs when I get the chance, practically a brand new Peerless. Returns look to be, two 1&1/4" returns plus the 3/4" copper going into a 2" manifold on the floor that runs through a wall into the boiler room. All have main vents that look like they have been spitting water over the years, especially the copper. No valves installed, ( king or return line ), for blowdown. Believe boiler has a fair amount of mud in it, along with returns. Extra 3/4" tap on top of boiler will allow for flushing as best as possible. Still have to get the OK from the powers that be. I looks like a good crawl space project for the hot summer days.