Black iron and galvanized pipe

Depends on who you ask, but my understanding is that galvanized is probably OK if you don't have glycol in your system.

If you go to a plumbing supply house, you can get all the black iron fittings and pipe you want or need. That can save you quite a bit over shopping at the big box stores, as you can get the fitting you need, instead of having to cobble two or three together. That can get expensive, even with black iron.

I'm not a boiler engineer, but on the various metals, I can say it will really depend on how much of each you intend to use. Looking at the galvanic series for the metals you mentioned, they would be:

galvanized steel/iron > iron pipe > yellow brass > copper > bronze

This is in order from most easily corroded on the left to least easily corroded on the right.

This also depends quite a bit on geometry. If you have one galvanized fitting on a run of iron pipe, that galvanized coating will be corroded in short order. If you have one iron fitting on a run of galvanized pipe, the galvanizing will hang around for quite a long time. Likewise one iron fitting on copper pipe, the iron will corrode pretty quickly, while one copper fitting on iron pipe, the copper will stay around for quite a while.

It will also depend a bit on your system - if you fill up with water and run that water for a long time so it becomes fully degassed and is properly treated, the system will have a long, healthy life. If you continually add make-up water (with fresh oxygen, co2, etc dissolved) it can lead to additional corrosion.

I've found that if you go to farm auctions and yard sales you can pick up pipe fitting by the bucket for almost nothing as people use very little pipe anymore. I've bought lots of it and when I need something I usually have it. Tons of new iron pipe fittings are going to the scrap yards because very little is being used in the factories so if you do some looking you just might save your self a bundle.
leaddog

The big advantage of ball valves is that you can tell by looking at them what they're set at. With a gate valve, you have to seat the valve to know where you're at, and by then, you forgot where you were. So ball valves are better for any application where you may not be all-open or all-closed. Not having any empirical data to back up my preference (what else is new?), I would tend to trust a gate valve in applications where a good seal is essential. My impression is that ball valves are more prone to leaking, especially after they've been sweated and re-sweated a couple of times. Crap in the water can scratch the ball, causing the seal to leak.

If you're going with black iron, get some threaded gate valves (ball valves come that way, too) and you'll save a bunch more by not having to buy thread-to-sweat adapters. A 50-cent black iron nipple is a lot more fun to buy than a $5 sweat-to-thread adapter.

I got 8 1" threaded gate valves for $50 on Ebay (an Ebay store, not an auction), shipping included.

Either one; sometimes both.

I usually use teflon tape, but if I'm not sure about a joint or if it's giving me trouble, I'll put down a layer of dope, some tape, and then maybe another helping of dope.

Be careful cranking on those brass valves They're not as strong as the iron, and they can crack if you tighten them too much. I've had iron fittings crack as well. Smaller sizes should be spun with smaller wrenches, in other words.

Tony H said:

Any reason I should use ball valves over gate valves ? The price difference is quite a bit.


Thanks for your help

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I like ball valves if I'm going to open and close them alot as the gate valves tend to leak at the stem under use. When buying valves look for ones that have large opening in the valve or else you will choke the flow. Some valves have 1/2 in openings on a 1in valve etc. Also don't use valves with rubber seats for opening and closeing alot as you will have to change seats over time. Gate valves tend to give better control on partial opening than ball valves as ball valves work better open OR closed. Auctions, yard sales, ebay are the place to buy.
leaddog

Ball valves are positive shutoff, gate valves MAY shut flow off at first, but usually leak thru after awhile. Gate valves are better for balancing/flow adjustment than ball valves. Make sure you use full port ball valves (full opening size vs. reduced).

A gate valve or ball valve is not meant to balance flow, that is what globe valves are for. Regulating flow with a gate valve can damage the seat over time and are very finicky to get a specific pressure drop across it for balancing.

Tony H

Use Black pipe it's less expensive and Galvanized can break down under certain chemical conditions. Bare steel is pretty inert if you monitor your water quality and composition as you should.

Buy your supplies from a supply house, not Wally World or Home Despot, there's a difference plus a supply house will have reducers and fittings that the other places don't know exist.

Don't mix galvanized and black. I've seen some really weird corrosion in systems like that. Dissimilar metals sometimes don't like each other.

No need for Dielectric unions if you follow the next piece of advice. They always wind up leaking anyway after a few years.

On the subject of corrosion, we always drive a separate ground rod for the equipment and bond it to the boiler itself and the piping.

We use Loctite #55 thread sealing cord and a lick of whatever pipe dope for a guaranteed drip free joint. You can get it from any WW Grainger store.

I love the look and durability of a well made up black pipe installation. Can't beat it.

The cheap ball valves you get at HD, Lowe's or other big box are junk. If you can find a supply house that sells Webstone, Apollo or Legend.......well maybe not Legend........ ball valves, those are what you want to use.
Gate valves are obsoleteIMHO. Globe valves are what you use for throttling or balancing. Ball Valves are best for general use as they don't erode lover time like a gate does.

Heck, e-mail me a material list, I distribute Webstone valves and Ward fittings. I'll get you the right stuff.

We run into a lot of imported fittings that aren't even bored straight. You thread a nipple into an ell or tee and the thing takes off about 5 degrees from plumb. Aggravating to say the least when you're trying to be fussy about a job.

If you use mostly black steel, don't mix one or two galvanized fitting in, they will be attacked. If you use mostly galvanized, its fine to mix a few pieces of black in.

If you don't have much copper, use a good thread sealant and you'll likely be ok. If you have a lot of copper, ie more than the steel you're using, it will rot out the steel if you don't have a dielectric coupling.

Before I retired a rep came in and gave us a seminar on the Loctite products. Loctite 561 pipe stick worked the best for us. We stopped using Teflon tape.
As I understand the tape acts like a lube so as to get tighter. With the 561 it seals without cranking on the fitting as hard. Used it on water,air and hydraulics.
It also comes apart easier,it doesn't set up.
On my wood gun the 1 1/2'' copper male that fit in the boiler had several layers of tape and dope and still only had a couple threads showing so as not to leak.
That was before 561, just a good product.
Have anyone installed screens in line to collect corrosion particles?

I'm thinking of a basket strainer if I can't flush the lines out really well first.

Not sure how competitive their prices are on black, but NutsandBolts.com sells the stuff. I was looking for something else there when I found it.

Nothing beats having good dies for threading pipe and doing it properly. I hate seeing overtightened fittings to control a leak. You actually can ruin the thread causing more problems. Any premium pipe dope/tape works well with proper threads.

True pipe threads are designed to be tapered and seal without sealants but I don't know anyone who would design on that basis these days! I like looking at the hundreds of 1" perfectly welded pipe in older power plants. Some of the work is just beautiful, no body welds stuff today though. Thread or grooved.

slowzuki said:

True pipe threads are designed to be tapered and seal without sealants but I don't know anyone who would design on that basis these days! I like looking at the hundreds of 1" perfectly welded pipe in older power plants. Some of the work is just beautiful, no body welds stuff today though. Thread or grooved.

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I feel like a dinosaur............................

Interestingly enough I do a lot of pipe fitting on ships and much of it is welded. It's just easier to get the fit up perfect (to me any way). Pipe fitting tends to be one of my favorite jobs among many. My dad was a professional pipe fitter and I was doing lead joints on sewer lines by the time I was ten. I am thinking about welding up much of my wood boiler install.

BTW-check out a wye-strainer and maybe just put a blow down valve on it.

Thats what I was thinking for a strainer, I spec them on water supplies here and there when we can't flush the lines.

I love the workmanship that goes into a nice welded joint, I've never had much luck getting one to look nice myself but I'm too cheap to buy some nice capping rod! I looked into welding but PEX is so cheap and fast and freeze resistant its hard to justify welded.

I came across Fred Seton's site http://www.radiantdesigninstitute.com/page42.html. The site makes for really good reading.

DIELECTRIC UNIONS:

Here is a very misunderstood fitting, that is seldom used properly. The problem that a dielectric union is suppose to solve is a dissimilar metal problem between steel and copper, such as a steel water tank and copper pipe. Dielectric unions in a hot water heating system are nothing but trouble and usually leak in a short time. The antifreeze, boiler additives or acid water conditions cause the gasket to deteriorate.
There are better ways to handle this problem: FIRST REMEMBER THAT COPPER HAS NO PROBLEM WITH BRASS OR CAST IRON, IF YOU PUT A BRASS OR CAST IRON FITTING BETWEEN THE STEEL AND THE COPPER THE PROBLEM IS SOLVED. EVEN ON A HOT WATER TANK, A BRASS NIPPLE OUT OF THE TANK WOULD BE THE BEST CHOICE.

I assume that includes brass valves and fittings? Or are most of them bronze?

Eric Johnson said:

I assume that includes brass valves and fittings? Or are most of them bronze?

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I believe he means brass or bronze, fittngs or valves. In my experience with large made up flanges of cupro nickel material mainly, when steel bolts are used across a gasketed flange bonding straps jumpered across the flanges reduce the galvanic action on the steel. Some salt water systems are designed with a "waster" piece of a heavy gauge short steel section to be replaced periodically. An electrical engineer friend of mine has taught courses on corrosion control. There can be a lot to it.