rejoin 1\" iron pipe in-slab radiant after removing rusted sectio

lee_7

We have used Dresser couplings to repair this type of problem. Probably not the greatest answer, but they work and have not leaked yet, knock on wood.

Michael Baltay

rejoin 1\" iron pipe after in-slab radiant repair

Hello,

I have a nice old in-slab radiant heating system with 8 circuits in ~5000 sf that works great... until I sprung a leak last season. From what I can tell the system is actually in really good shape for its age. Anyway, my plumber used his infrared camera to help me locate the leak and I isolated that circuit. Since then I have cut open my slab and removed a rusted out section of the pipe. It looks as if there was a butt weld and just next to it on the underside the pipe rusted out over time. In the course of pulling out this section I got a look at an adjacent pipe and it looks fine. I also cut back far enough (about 18" to either side and found good solid pipe. So I cut out the rusted section, threaded both sides and am trying to join it back together.

Problem is that the pipes have absolutely zero give to them, either longitudinally or angularly. In order to make it up, I needed to use a length of iron pipe and two unions. It was not possible to use a coupling and one union. To do so I had to make the new section almost .6" shorter than actually required just top be able to install it over the rounded portion of the union fittings. I tried to then back off all 4 nuts each a little bit tpo make up the section, but alas it's not up to my standards. I can get it to hold 10 psi or so, but I can tell that it's just too fragile. I had to back the nuts too far away and each of them is leaking a tiny bit.

Question is what to do? I would prefer to stick with iron pipe, but can't think of a way to join it short of welding. That would work but will probably require more diging, of which I have had enough. I could go to 1" PEX, but I am afraid of burying those brass fittings into the new cement which I will have to pour. Do any of you pros have any suggestions? I suppose the PEX connection wil probably last 10 years or so, but I do not think it's good practice to bury that in concrete. I could figure out a way to encase it in a protective shroud, I guess. I could also go to copper somehow, but that is going to face similar problems with inflexibility of this situation as I ran into with iron.

Would appreciate any good ideas. Have photos if u want to see them.

Thanks a million,
Michael Baltay

Michael Baltay

Thanks for your rapid response-

Dresser is a ood suggestion. If I rember correctly, those use a gasket to make a seal with the pipe OD, correct? In which case I am going to really need toclean up the circumference of my existing pipe.

I also rember using a dresser coupling that was orange colored. If I am not mistaken, that one required a flanged end on the pipe itself.

Any experience burying PEX in cement?

Thx
Michael

steveex

Simple, use a 4 elbow swing and thats that.

Joe Billow_6

I would use Pex. You could use a braided stainless steel line too.

Michael Baltay

Thx- good idea. It would be great if I had the real estate. Right now I have a 4" wide opening by 40 inches long in the slab. I have wider openings cut at each end which are about 6" wide, where I planned my original fittings. The pipe sits about 1 1/2" below the surface. There is limited space below the pipe as well.

Michael Baltay

I like the idea of braided stainless because I can make it up with two threaded fittings. I will get a quote on a custom sst line with FPT on both ends. Do you have any experience burying PEX connections in cement?

Thx for all of ypour great suggestions.
MB

singh

I would consider

a left and right coupling and nipple. Use a regular coupling and short piece to make up difference.
I have no experience yet with burying pex fittings in concrete. But if I did, I would sleeve them with insulation or something.

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steveex

When i have to use pex fittings in cement i always duct tape the hell out of it. Just in case.

Michael Baltay

Status

Hello,

Thanks for all of your great ideas. Sorry to have gone a bit silent. I've been working on this repair.

So, what I tried in the end is a flexible metal hose (thx. Joe Billow). It's essentially a 12" piece of SST corrugated with a SSt braid over it and it has MPT 1" on both ends. That has plenty of give in it to easily make up the repair. The union itself must have a burr on it or something because no matter how tight I get it there is a tiny bit of air leaking out. Other than that the line now seems pretty sound. I am still worried about having to bury two couplings and the union. I may redo it in the next day or so with PEX and just enclose the PEX fittings in good dusct tpe or some other waterproofing type material.

BIG problem now is that I hear a new small leak just upstream of this repaired section. That said, I really think this leaky area is all because of the primary leak I already found near that one bad weld, but over the years there has been much more water and rust in and around this area. I actually am surprised that there is a second leak because the pipe itself is in great shape near there. So now I need to sleep on the mess and decide if I am going to chase leak #2 down. I have been testing at 40psi air and I am worried that this is a bit strenuous. On the other hand I don;t want to replace the whole floor with new floor covering just to find I get steamy hot moisture seeping out again.

Thx. again,

I'll provide a status update when I get to the next milestone-

best,
Michael

tim smith

I would take new piece of steel pipe, butt it up and have it

welded. This would be the most sure repair. Sounds like you have enough room for welder to do blind weld on under side. May have to expand the trench a little where welds needed but not a big deal.. If you stay with what you have in there, don't use a union, use r/l coupling and nipple with the braid flex. Better long time solution.

bob young

use two flange unions & drop in a spool piece

oil-2-4-6-gas

welding on any of the pipe will be a problem you weld it ,it leaks on the old then you weld again it may leak you need to find very sound pipe --though mig welding would be less aggressive -- i am good friends with a welder who does a LOT of buried wet returns under slabs many of his jobs are chasing leaks and keeps going until you find some good pipe which is a crap shoot //////

Joe Billow_6

Use black electrical tape. Duct can degrade the pex. I would also teflon tape and use a good pipe dope on all the fittings. Another trick is to use 680 loctite which will never come apart. I use 680 anywhere there is a chance for a leak in an inaccessible area.

Mark Custis

I agree with Joe on the electrical tape. That is the fix my main pex source recomends.

I have not used any of the products, but I have heard there are epoxy lining systems out. You could also line the run with pex.

Just my thoughts.