Making up threads and your opinion on dielectrics

[Deleted User]

i tried your gauze method on a 3'' threaded watermeter flange thats been driving me nuts, and it worked great. thanks for teaching this old dog a new trick. worked so well my jaw is still hanging open.

David Van Wickler_3

Making up threads and your opinion on dielectrics

An engineer friend of mine inherited a 9,000 sq.ft. 250yr old mansion. He has ripped out the old Smith 10 section 5gph oil converted from coal boiler and is installing two C.I. Dunkirks. I have helped him design a primary/secondary injection system with pex run-outs to each cast iron radiator. The house is seperated into 4 main wall mounted set-back thermostats and individual thermostatic zone valves on each radiator.

The questions are.....

My friend is an engineer - did I mention that?

He is concerned about the makeup of the 2" primary piping. He is piping the boiler with steel pipe and converting to copper for the injection and secondary piping then coverting to premade welded steel manifolds.

How would you dress the threads? with 3 wraps of teflon tape then pipe dope? Or just tape? Or just pipe dope? Anybody try the new teflon rope?

Question 2:

What do you do where the steel transitions to copper?
Use dielectric fittings?
Use brass between the steel and copper?
Nothing at all, i.e. steel into copper?

other?

Your help is always respected - TY.


DVW

Mad Dog

Dielectrics are a nice touch............................

but not absolutely necessary...I've tried all kinds of teflon tapes and dopes...and you know what??? I'm back to lampwick and Rectorseal on all my boilers steam and hot water. Mad Dog

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heretic

Dielectrics

I recently posed a similar question regarding dielectrics, and the Wall consensus was that there is not enough free oxygen in a closed FHW system to feed the electrolytic reaction between copper and iron.
For the record, my own FHW piping shows no substantial corrosion where steel meets copper after 15+ years, nor have I seen any problems with this very common mix in other old homes.

In comparison, my domestic water piping shows serious corrosion wherever copper and iron meet, particularly for hot water pipes, and some recent fun failures. Must be that 'free oxygen' at work!

Bill Clinton

pipe dope

There is a new pipe sealing cord I saw at ISH. It's now being marketed in the US by Locktite. It's called Locktite 55 and has a part number 35082. I've been using it for a few months and am real happy with it. Used to use both teflon tape and dope. Now just use the Locktite 55. It's at least as good and I suspect better.

I never use dielectrics on closed systems. Haven't in twenty five years with no problems. Have serviced boilers fifty years old with no dielectrics and they're fine.

Bill

eric_2

Dielectrics

will never hurt the system. While not an absolute necessity in a closed water system, you can never take too many precautions especially when it's your project. I've always been old school when it comes to such things. The cost of a dielectric nipple investment far outweighs the cost of future repairs or replacements. Just my opinion....
Have a good weekend Wallies!

Duncan_2

Got muscles?

Any pipe 3/4" and below, Rectorseal #5 pipe dope. One inch pipe and above, tape plus dope. The tef tape makes it easier to snug up the bigger (*snicker*) stuff. Plus, it makes it easier to take apart, if you pipe like I do. (That Locktite wrap sounds like it's worth checking out.) A minor drawback is that the pipes move from plumb and level easier as you install, since the joints unscrew easier.


Forget the dialectrics, the gaskets just harden and leak over time with high boiler temps, IMO. Anyway, for galvanic action to take place, there's got to be an electrolyte, a charge carrier. In a closed system, aggressive water initially attacks the pipes, but quickly uses itself up and becomes neutral with microscopic, if any, noticeable effect. Certainly no harmful level of corrosion.

Experience talks, bull walks. Like others point out, there are LOTS of thirty and fifty year old systems with mixed metals / no dielectrics that are clean machines, inside and out. Steel and copper are fine, from what I've seen, and I pipe accordingly. Open systems are a different animal.

pfitter_3

Dave;

First, If it were my home, I wouldn'nt worry about the dielectrics. I would, more than likly, put a brass ball valve ( Apollo or Hammond) at each take off at the header. If I was working a job that spec'd Dialectrics, I would use the nipples made by Victalic. Advoid the unions as much as possable.

As far as dope, I would throw a couple of wraps of tape then top it off with Prodope or a teflon paste. Remember, the seal is in the threads and your arms. Nothing substitutes for good threads properly installed. No fancy dope will make up (it might mask) a problem with the threads or installer.

By the way.... wernt you writing a book? did that ever come out?

P

Paul Pollets_2

I'd use

3/4" teflon Kanga tape, which is much heavier than normal teflon. Or use gas fitter's teflon tape if your dealer doesn't stock Kanga tape. with Kanga, I use 3 wraps, with normal, 7 wraps and some Megablock dope under the tape. I never use dialectrics on a closed loop system. They often leak at the gaskets. I use black or brass unions.

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hr

Skip the dielectrics

on heating systems. More trouble than they are worth. Glycol and many other boiler fluids will react with the zinc on them. Is a dielectric really rated for 180 degrees or more continously?

The CDA states they are not necessary on steel to copper on hydronic and fire protection piping.

hot rod

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J.C.A.

Gotta \"pipe\" in here...so to speak.

Granted as was pointed out , the thread is the seal . My personal problems have been with pipe made in U.S/Canada, or unstamped old stuff(more likely than not American from the heyday)and mating copper fittings/adapters to it . There was always at least 1 leak from a copper fitting to a black iron fitting leaking till I took some advice from an "old timer " His thought was a light coat of dope (pick your poison) , a couple or 3 wraps of tape (again pick your own) then a light coat of dope again .I've been doing this for 15 years and haven't had a joint leak. So I'm gonna stick by it ! It takes a little more time , but doing it once saves me from doing it over .(BTW .. plumbers were the ones laughing the loudest while I did this . When the oil co.I worked for got too backed up we hired out boiler work . The same plumbers weren't too happy to be coming back for free... to fix the leaks on the joints I explained .Time teaches...callbacks cost.)I've learned albeit the hard way that Taco got the best tag line in the industry....Do it once...do it right!. Chris.

pfitter_4

Rod

Whats the "CDA"? Is there any written standard that adress's the temp rating or zinc reation? I would just LOVE to be able to pass that on to an engineering firm or two that insists on filling up the systems they design with dielectrics. I always figured they owned a zinc mine or sumptun'.

p

Unknown

Chris

Do you coat the inner threads on the fitting too ? I started doing that a few years ago and havent had a leak since - compared to maybe one leak a month or so when we just used Teflon and Rectorseal on the outer threads alone . You know , those jobs where you wish the fitting will heat up and seal itself - but never does .

hr

Corrosion of mixed metals

CDA stands for Copper Development Association. www.copper.org they have volumns of information on copper installation and trouble shooting.

Generally with steel, or iron, to copper the relative mass of the metals plays into the potential for corrosion. Connecting copper to a cast iron boiler, especially with teflon or pipe dope on the threads is considered a safe install. Steel and iron are anodic to copper, but they are in close proximity in the standard galvanic series, so corrosion potential is defined as moderate.

If you were to connect lengths of copper tube together with a small steel or black iron coupling the potential for corrosion at that small mass of steel or iron would be very high. That steel coupling would be attacked and short lived!

Copper and steel or black iron have been mixed on fire protection systems for years without problems, also. Many wet systems in cold locations use glycols for frexe protection. Use of zinc coated (dielectrics or galvanized fittings) is a no- no with inhibited glycol products.

Hope all this helps somehow.

hot rod

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hr

Coating the inside threads

especially on large diameters or questionable threads will help the leak issue.

However much of that pipe dope will end up pushed into the pipe and fluid in the system. You really would want to flush that system, and run a cleaner or TSP solution through it. Pipe dope, cutting oil, and solder flux residue combine into some pretty ugly slop inside those boilers and pumps
I understand steam systems are sensitive to oils, etc in the system, also.

hot rod

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canuckDale

> 2\" threads tip

On big stuff... dope the threads, wrap with 1/2" first-aid gauze just like teflon. Dope again. Walk away and never look back.
Old plumbers would do the same with cotton-wick on big threads. Any leaks cause the fiber to expand.

[Deleted User]

ive had good sucess doing the following

if im going to put together steel to steel, or copper to steel, or brass to steel, i use pipe dope.
if im going copper to copper, or brass to brass, or copper to brass, i use teflon tape.
has seemed to work out for me...but im intrigued by the use of both..im going to try this.
i have used dope on the female threads also, but only on 2'' and larger steel gas fittings cause they would inevitably be in the middle of the run and be a bear to dissassemble back to, if furthur tightening were required.
we use drip/dirt legs here so i wasn't so concerned about some dope getting into the system tho.

Duncan_2

Neat trick.

Here in the states, when the Feds -Tabernacle!- take away the hemp that comes with Euro threads, gauze has to do. It works!

I gotta laugh when I think about the first time I stumbled across straight threads. We ended up doing exactly what you describe. My friend and I found out the hard way. An early model Buderus came shipped without hemp. We didn't know what kind of threads we were dealing with, even though we saw the light notching across the threads (to grip the hemp?). We had leaks EVERYWHERE - Tom thought of using cotton gauze all on his own, and it worked great!

Amazing, the stuff you come up with when you have to. Glad to hear it's an accepted practice.

Dale W.

copper to steel

Copper and steel mixed on an open or closed system seem to leak more frequently when the copper fitting is female and the steel is male. I always add a steel fitting to the steel male threads so I have a steel female thread to screw in a copper male adapter. Copper female adapters leak far too often for me. I also use the teflon tape and rectorseal approach on any steel to copper joint.
Dale Wegman

HBW

Pipe Dope

Ran over 1500ft of 3" black with some copper & brass, used xpando, have to degrease the threads after they came off the threader. Had no leaks.

Joe at krahezfoo@aol.com

Connecting dissimilar metals

In the thirty years that I have been servicing boilers I have seen a lot of corrosion problems where dissimilar metals are connected. This includes water regulating valves and low water cutouts. The cost of installing a dielectric union or a waterway is minimal; compared to the cost of you losing your reputation as a competent mechanic. If the job is bid that close, it's not worth taking; it will come back to bite you! Not saying that lots of teflon will produce the same results; but why take the chance? All it takes is one micron of exposed metal to start the corrosion process. Do it right the first time! Your name goes on the job.

canuckDale

Glad it worked for you!

You're right. This site is educational.

And it's the uninhibited conversation and sharing of methods that allows us to learn... new?... old? Awww same stuff just different faces!

Glad I could help.

Dale

pfitter_5

A little trick...

Screw the copper female adapter on to the male thread well it is still hot ( the Fm that is) when it cools it will be leak proof. Use your favorite doping method on the threads before making it up. Dont heat it so hot it frys the dope.

p.

Unknown

How much of the pipe dope

that will go into the system , I believe will be fractional . We use Rectorseal yellow , and that stuff is soft set , goes on almost like paint . This is one of the reasons I like to purge out my boiler systems with hot water - I think it brings back alot of the byproducts of the installation like you said - sealant , cutting oils , flux . I think we get alot of it out, or at least dilute it enough to be of no consequence . It is well worth the minimal risk involved .

Floyd

Expando is great....

just don't EVER try to get it apart!!!! espec. 3"
Even on small stuff you will have to put a BIG wrench on it and hammer it with a BFH!!!!

Floyd

HBW

Break-EM

You right, we have had to break some fittings on occasion, not an easy thing to do, but still possibile.