I have a leak on my 3 inch main

GW · November 14

The older I get, the more questions I ask. I’m going in reverse!

We popped the new steam boiler in. I was trying to get extra fancy by getting rid of a section of 2 inch and I installed some 3 inch.

I’ve never use Teflon tape on the steam mains. In this case, it looks like whoever threaded this 3” piece 80 years ago ran the threads extra deep.

I started up the boiler and the coupling was dripping at a fast rate. I need to take it apart, but unfortunately, I need to do un spin quite a bit of the piping at the boiler to get back to this thread.

What do you think, load this thing up with Teflon tape and put it back together?

Maybe I should put a union there in case it continues to act up?

This coupling is in a very slight dip. The section is traveling about 8 feet towards the steam system. The new section is traveling with a 5 foot pipe, to the boiler. The new section drains away from the boiler, as it should. The section in the wrong direction, hence the teensy belly at the coupling.

The system was making zero noise, so I suspect the puddle of water where the coupling is is not causing any ill effect

thanks for any tips, hoping not to spend a whole lot more hours on this

Amazingly, the homeowner said the original system did not make noise. Which is somewhat fascinating. No header, no equalizer. no Hartford loop. Not that that has anything to do with noise.

offdutytech · November 14

Tape it with 3/4 teflon with a few extra wraps, then use a good quality pipe dope. Usually takes care of it. I would rather use a pipe flange connection than a 3" union .

mattmia2 · November 14

ball wicking in the threads then dope. or the thread sealer type loctite. or hardening thread sealer. there are lots of ways to do it. if it is leaking with just dope then there is a gap that is too big for just the viscosity of the dope to seal so anything you put in there will seal it, string, teflon tape, hemp, setting type dopes.

GW · November 14

thanks, I’m sure it’s simple but taking the piping apart is gonna take me time. I’d rather ask the stupid questions now. The yellow Rectorseal number five was very soupy. I should’ve known better.

JUGHNE · November 14

I would go for the flange. It takes a pretty large pipe wrench to tighten a 3" union.

And using anti-seize compound on both sides of the gasket will help in the future to remove the gasket if needed.

ChrisJ · November 14

Xpando to the rescue

ScottSecor · November 14

I am assuming the inside of the old 3" main looks great. Wire wheel threads on old 3" main, closely inspect shiny threads. Five wraps of thick 3/4" Teflon tape. Heavy coat of Megalock pipe dope on top. Crank with (2) three foot pipe wrenches. You will feel when it's tight.

Or, cut wire wheel exterior of old 3" main. Cut at clean section, make sure pipe exterior is smooth (confirm no wrench marks or gouges). Purchase and install 3"x 12" long steel nipple. Cut threads off end of nipple, clean same. Install 3" Megapress slip coupling connecting new half nipple to old steam main.

ethicalpaul · November 14

are you saying you never use any sealant on steam pipes? 😱

ChrisJ · November 14

https://forum.heatinghelp.com/discussion/comment/1909516#Comment_1909516

He said he's never used Teflon tape.

I assume he uses dope on them but as I proved just oil alone will work fine on good npt threads.

ScottSecor · November 14

If your asking me, Megalock claims it is a sealant. Also some Teflon tape manufacturers claim their product is a sealant as well.

https://www.oatey.com/products/P_032628158061/hercules-megaloc

GW · November 14

https://forum.heatinghelp.com/discussion/comment/1909510#Comment_1909510

J do you think the flange set up would be pretty close to the coupling set up? So the pipe spacing will be similar?

ScottSecor · November 14

For clarification, this the current method we use when working on roughly one hundred year old threads on three-inch steel pipe. Gary mentioned this original pipe have have been threaded further than standard. I was trying to specific to Gary's situation.

Alan (California Radiant) Forbes · November 14

Loctite thread - maybe doubled up to fill the groove - along with a good layer of thick pipe dope. I'd even dope the female threads.

mattmia2 · November 14

or the teflon cord version of ball wicking as @Alan (California Radiant) Forbes posted. those other fittings looked like they might need a bot more thread engagement too but others might have comments on that and the tolerances in the pipe size and the threads and the fittings will change how those make up in an specific pair of fitting and pipe.

hot_rod · November 14

A 3" Fernco :)

Steamhead · November 14

https://forum.heatinghelp.com/discussion/comment/1909512#Comment_1909512

I would never use MegaPress on a steam main. The sudden expansion and contraction runs the risk of wearing out the internal O-ring.

mattmia2 · November 14

https://forum.heatinghelp.com/discussion/comment/1909533#Comment_1909533

split cv joint boot

ScottSecor · November 14

3" companon flanges will likely take up a little less space than the coupling. Often the steel threads almost come through the flange face, maybe one thread back. On most 3" threaded black couplings of your type, the ends of the pipe are approximately 1/4" to 3/4" apart (space between).

mattmia2 · November 14

https://forum.heatinghelp.com/discussion/comment/1909547#Comment_1909547

it looks like that corner can move a little to take up an inch or 2. maybe just cut the coupler out and replace it with flanges(or even a union) instead of re-fitting it back to the boiler.

GW · November 14

I could cut the coupling out. I’m a little worried that I might kick the main a slight bit.

JUGHNE · November 14

Could you change the length of the new 3" nipple you have before the coupling.

Something will have to be cut unless you go a long ways back to the boiler.

I would cut out the coupling and see how close the flanges would land and then maybe get a longer nipple or try to move the pipes closer together.

I have a leak on my 3 inch main

Comments

Categories