Slightly backing out an old threaded connection?

[Mliu]

I lease a commercial space with heating and cooling provided by the building's boiler/chiller system. Recently, a leak developed in the hot water pipeline that feeds the fan coil unit (FCU) in my space. I've never been impressed with the quality of the work performed by the company that is contracted to do maintenance & repair on the building's HVAC, so I should have performed this repair myself. But I have had my hands full with several other projects, so I put in a maintenance request with our management company to have their contractor repair the leak.

After a month, the contractor finally came out and found that the leak was coming from a 3/4" dilectric union between the iron pipe from the boiler distribution piping and the copper pipe that feeds into the FCU. A few weeks later, the contractor replaced that dilectric union. The problem now is that the iron pipe and the copper pipe are no longer in alignment, as you can see in this photo:

It was not like this before the repair was made. I suspect what happened is that the contractor put a single large pipe wrench on the old dilectric union to remove it and pulled down hard to unscrew it (he probably hung all his weight on the wrench). This caused the iron pipe to rotate down at an upstream elbow, just to the right of the valve in the above photo. Below is a photo of the elbow, and I believe the contractor caused this elbow to rotate a few degrees clockwise, making it tighter.

The contractor spent a lot of time trying to get the dilectric union installed and, of course, it kept leaking because the iron and copper pipes were not in alignment. After a few hours of monkeying with it, he finally got the union to stop leaking. I told him not to re-insulate the pipe or close up the ceiling at the time (because I was not confident in the repair). Sure enough, after he left and hot water started flowing through the pipe, the union started leaking again. So he came back out the next day and monkeyed with it some more (uncoupled and recoupled the union, and probably tightened the crap out of it) and he finally got it to stop leaking.

It's been over a month now, and it's still not leaking. But the weather warmed up right after the repair was made, so no hot water has been flowing through this pipe since that time. I am not confident that the union will remain watertight once the cold season starts. Even if it doesn't start leaking in the fall or winter, I'm not comfortable that this joint will remain watertight over the years because it's such a hack job, with the union trying to seal two pipes at an angle. So I feel I should remove and replace it myself.

As you can see in the photos, there is another branch that tees off the iron pipe before the union, so I can't simply disassemble the iron pipe to re-align it. Besides, the elbow that was turned is upstream of the isolation valve, so re-making that elbow connection would require taking the building's entire boiler system offline and draining it.

So the question is, can the iron pipe be rotated backwards a couple of degrees (essentially loosening that elbow joint a tiny bit) to get it horizontal again? Or will the risk be too great of a leak developing at that old elbow connection? I've done a lot of plumbing work over the years, but I've never tried loosening a threaded pipe connection before to get pipes to align, especially not on a very old connection. Even though it would be only a couple of degrees of rotation, I'm not confident that this would be a good idea. If it truly is unwise, then how would you recommend fixing this misalignment between the iron pipe and the copper pipe?

 

[Breplum]

I wouldn't want to risk rotating any of the big threaded piping. I would put a 4.5" or 6" brass nipple in and ProPress up female adapter and add a slip coupling if necessary.

 

[Sponsor]

 

[Mliu]

I wouldn't want to risk rotating any of the big threaded piping. I would put a 4.5" or 6" brass nipple in and ProPress up female adapter and add a slip coupling if necessary.

Yeah, my gut feeling was that trying to rotate the pipe back to its correct position would be a bad idea, especially on a joint that is many years old. If that hack contractor had simply used a second wrench to keep the pipe from moving, I wouldn't be dealing with this crap right now. (Not to mention the mess he made of my walls, ceiling, floor, and the top of my commercial refrigerator.)

I'm not sure how the brass nipple would help with the pipe alignment issue. Also, I'm not a fan of ProPress, so I want to remove that ProPress coupling he used and replace it with a sweat coupling.

Probably the best solution would be to add an 18" length of 3/4" soft copper tubing in place of the rigid copper pipe after the union. The soft copper tubing could be bent to correct for the misalignment. The problem with that is cost: a 60' coil of Type L soft copper tubing costs over $700. I imagine it will be unlikely that I'll be able to source only a short section of 3/4" tubing.

Now that I think more about it, I suppose I could take a piece of 3/4" rigid copper pipe, fill it with sand, heat it with an oxy-acetylene torch to anneal it, and then use a conduit bender to put a slight angle in it.

 

[John Gayewski]

Dielectric unions are not very good. They tend to fail even if installed in alignment.

If you are gonna drain the system and do the work just take most of that apart and re tape and dope the joints and put it back together with your preferred fittings. Brass nipple and female adapter to go from black to copper works. Stainless even better.

 

[Mliu]

Ok, I now understand what both of you are talking about with the brass or stainless nipples. But I have to disagree with this solution. The purpose of the dielectric union is to interrupt galvanic (electric) currents between dissimilar metals: in this case, the galvanic current that is created when iron is connected to copper. The dilectric union does this by placing a plastic insulator between the two dissimilar metal pipes. Adding a brass or stainless nipple between the copper and iron can reduce the current by extending the return path through the electrolyte (the fluid in the pipe), but it does not completely prevent this galvanic current from being generated because both types of nipples are electrically conductive. (Also, brass to iron or stainless to copper are both disimilar metal junctions that will create their own galvanic currents, just not as much as copper to iron.)

That said, a more important reason for me to retain the dielectric union is because removing and replacing it with something else would change the engineered design of the system. If the piping later fails for whatever reason, then the building owner could, and likely will, hold me liable for the damages because I changed the system's design.

Btw, I will be replacing the cheapo dielctric union installed by the contractor with a quality dielectric union made by Watts.

 

[John Gayewski]

Ok, I now understand what both of you are talking about with the brass or stainless nipples. But I have to disagree with this solution. The purpose of the dielectric union is to interrupt galvanic (electric) currents between dissimilar metals: in this case, the galvanic current that is created when iron is connected to copper. The dilectric union does this by placing a plastic insulator between the two dissimilar metal pipes. Adding a brass or stainless nipple between the copper and iron can reduce the current by extending the return path through the electrolyte (the fluid in the pipe), but it does not completely prevent this galvanic current from being generated because both types of nipples are electrically conductive. (Also, brass to iron or stainless to copper are both disimilar metal junctions that will create their own galvanic currents, just not as much as copper to iron.)

That said, a more important reason for me to retain the dielectric union is because removing and replacing it with something else would change the engineered design of the system. If the piping later fails for whatever reason, then the building owner could, and likely will, hold me liable for the damages because I changed the system's design.

Btw, I will be replacing the cheapo dielctric union installed by the contractor with a quality dielectric union made by Watts.

I think you might be the most annoying type of person seeking advice. Two people with years of experience agree on a solution and you decide it's wrong. Do what you'd like to do but your union will rot three times before a brass or stainless nipple will cause any rot.

 

[Fitter30]

Right side of pic is a propress coupling. Wouldn't touch it without a another pp coupling and tool just in case copper would twist. Would use a flex connector to take the strain off the dia union. Start twisting on that old pipe to straighten might take 30 minutes or all day. Plus get rid of dia union.
www.supplyhouse.com/Chamflex-CH075012FM1000-3-4-x-12-ChamFlex-Hose-Swivel-MNPT-X-Fixed-MNPT?utm_source=google_ad&utm_medium=Shopping_HVAC&utm_campaign=Shopping_X_HVAC_X_SSC_New&utm_campaignid=22357738074&utm_adgroupid=176777929877&utm_targetid=pla-2351959153636&utm_product_id=CH075012FM1000&utm_matchtype=&utm_keyword=&utm_adtype=pla&utm_category=HVAC&gad_source=1&gad_campaignid=22357738074&gbraid=0AAAAAD_WAyvq_hhnFWg6Ob6SOBNELAvVT&gclid=CjwKCAjwprjDBhBTEiwA1m1d0l-Gp6Z1VUUnBpuAFEIHSZKhufA34T52u4Y52PfOGKwSBST-px_AMhoCNtQQAvD_BwE

 

[Mliu]

I think you might be the most annoying type of person seeking advice. Two people with years of experience agree on a solution and you decide it's wrong. Do what you'd like to do but your union will rot three times before a brass or stainless nipple will cause any rot.

I was not trying to disparage either of you. On the contrary, I am thankful that you both tried to offer advice. But I am not a novice DIYer. I also have years of professional experience in the trades (mostly in industrial settings), as well as a background in mechanical engineering (which is why I have an understanding of the underlying mechanism of galvanic corrosion). But my question was never about the use of dilectric unions. Rather, it was how to resolve the problem that the contractor (no doubt, also with years of "professional experience") created by torquing the pipes out of alignment. I've never created this problem myself, and when I've encountered it before in other people's work, I've always been able to disassemble the offending connections and align them properly. This is the first time I've faced a situation where it's completely impractical for me to disassemble the old pipes to realign them. That was why I came here seeking advice (and Breplum was kind enough to confirm my concerns that it would be unwise to try to move the old pipes back into alignment).

Btw, I never said either of you were wrong about the nipples: I conceded that using a brass or stainless nipple will reduce galvanic corrosion. But it will not eliminate it: that is a fact of physics. Would a brass or stainless nipple provide better longevity than a dilectric union? Possibly yes, possibly no. That depends on the quality of the dilectric union, the quality of the installation, and the electrical conductivity of the fluid in the pipes. But I clearly stated that the MAIN REASON I cannot replace the dilectric union with a nipple is one of legal liability, and that would still be the case even if a nipple is 100% guaranteed to be superior to a dilectric union.

I'll also add that the biggest complaint about dilectric unions seems to be with the deterioration of the gasket over time. But how can one criticize the dilectric union for having a gasket while simultaneously supporting the use of ProPress fittings, which also rely on a gasket to make a seal? In my opinion, a gasket seal will never be as durable or long-lasting as a good sweat connection or a well-made threaded connection. But a high-quality dilectric union that is installed properly (with both pipes properly aligned) should last many, many years. The dilectric union that started leaking in my space was part of the original installation (I know this because the fiberglass insulation over it was original and undisturbed until the contractor removed it), and this building was constructed in the 1970's. Fifty years of service from a dilectric union isn't bad. I believe most pre-mature dilectric union failures are either the result of using low-quality parts or improper installation. In this case, the contractor failed on both counts.

I apologize if I unintentionally offended you or seemed ungrateful.

 

[John Gayewski]

I was not trying to disparage either of you. On the contrary, I am thankful that you both tried to offer advice. But I am not a novice DIYer. I also have years of professional experience in the trades (mostly in industrial settings), as well as a background in mechanical engineering (which is why I have an understanding of the underlying mechanism of galvanic corrosion). But my question was never about the use of dilectric unions. Rather, it was how to resolve the problem that the contractor (no doubt, also with years of "professional experience") created by torquing the pipes out of alignment. I've never created this problem myself, and when I've encountered it before in other people's work, I've always been able to disassemble the offending connections and align them properly. This is the first time I've faced a situation where it's completely impractical for me to disassemble the old pipes to realign them. That was why I came here seeking advice (and Breplum was kind enough to confirm my concerns that it would be unwise to try to move the old pipes back into alignment).

Btw, I never said either of you were wrong about the nipples: I conceded that using a brass or stainless nipple will reduce galvanic corrosion. But it will not eliminate it: that is a fact of physics. Would a brass or stainless nipple provide better longevity than a dilectric union? Possibly yes, possibly no. That depends on the quality of the dilectric union, the quality of the installation, and the electrical conductivity of the fluid in the pipes. But I clearly stated that the MAIN REASON I cannot replace the dilectric union with a nipple is one of legal liability, and that would still be the case even if a nipple is 100% guaranteed to be superior to a dilectric union.

I'll also add that the biggest complaint about dilectric unions seems to be with the deterioration of the gasket over time. But how can one criticize the dilectric union for having a gasket while simultaneously supporting the use of ProPress fittings, which also rely on a gasket to make a seal? In my opinion, a gasket seal will never be as durable or long-lasting as a good sweat connection or a well-made threaded connection. But a high-quality dilectric union that is installed properly (with both pipes properly aligned) should last many, many years. The dilectric union that started leaking in my space was part of the original installation (I know this because the fiberglass insulation over it was original and undisturbed until the contractor removed it), and this building was constructed in the 1970's. Fifty years of service from a dilectric union isn't bad. I believe most pre-mature dilectric union failures are either the result of using low-quality parts or improper installation. In this case, the contractor failed on both counts.

I apologize if I unintentionally offended you or seemed ungrateful.

The "fact of physics" doesn't hold true in reality. Any electrolysis caused with these metals doesn't show itself in practice. Use stainless it's stronger and had the added benifit of being cheaper.

Adding strength to a system or improving a design feature doesn't put you in any liability for things failing downline.

The fact that the original dielectric union leaked apparently adds no value to your judgment on this issue? It was probably the original contractor's fault. I'm sure they didn't know what they were doing either. I can see that you actually can't see what's right in front of your face and two people, who actually know what they are saying, are telling you how to improve this isn't helping either. Which means you actually can't be helped.

There's no offense taken, it's more like leading a horse to water and then shrugging your shoulders when they keel over from dehydration.

 

[Master Plumber Mark]

That could have been an easy fix if the guy would just have
cut out more of the copper beyond that propress fitting . Heating up the copper
and putting a slight bend in it to line up better with the steel pipe
would have been the easiest way to resolve that issue... its called a "German Elbow"

their is no way I would ever fool with that old steel pipe

 

[Fitter30]

I was not trying to disparage either of you. On the contrary, I am thankful that you both tried to offer advice. But I am not a novice DIYer. I also have years of professional experience in the trades (mostly in industrial settings), as well as a background in mechanical engineering (which is why I have an understanding of the underlying mechanism of galvanic corrosion). But my question was never about the use of dilectric unions. Rather, it was how to resolve the problem that the contractor (no doubt, also with years of "professional experience") created by torquing the pipes out of alignment. I've never created this problem myself, and when I've encountered it before in other people's work, I've always been able to disassemble the offending connections and align them properly. This is the first time I've faced a situation where it's completely impractical for me to disassemble the old pipes to realign them. That was why I came here seeking advice (and Breplum was kind enough to confirm my concerns that it would be unwise to try to move the old pipes back into alignment).

Btw, I never said either of you were wrong about the nipples: I conceded that using a brass or stainless nipple will reduce galvanic corrosion. But it will not eliminate it: that is a fact of physics. Would a brass or stainless nipple provide better longevity than a dilectric union? Possibly yes, possibly no. That depends on the quality of the dilectric union, the quality of the installation, and the electrical conductivity of the fluid in the pipes. But I clearly stated that the MAIN REASON I cannot replace the dilectric union with a nipple is one of legal liability, and that would still be the case even if a nipple is 100% guaranteed to be superior to a dilectric union.

I'll also add that the biggest complaint about dilectric unions seems to be with the deterioration of the gasket over time. But how can one criticize the dilectric union for having a gasket while simultaneously supporting the use of ProPress fittings, which also rely on a gasket to make a seal? In my opinion, a gasket seal will never be as durable or long-lasting as a good sweat connection or a well-made threaded connection. But a high-quality dilectric union that is installed properly (with both pipes properly aligned) should last many, many years. The dilectric union that started leaking in my space was part of the original installation (I know this because the fiberglass insulation over it was original and undisturbed until the contractor removed it), and this building was constructed in the 1970's. Fifty years of service from a dilectric union isn't bad. I believe most pre-mature dilectric union failures are either the result of using low-quality parts or improper installation. In this case, the contractor failed on both counts.

I apologize if I unintentionally offended you or seemed ungrateful.

Press fittings use EPDM and the manufacturer has to standup for their warranty. Dia unions can use rubber, buna n or epdm. Most unions don't have a manufacturer name on them especially from hardware and box stores. There is also two types of plumbing houses they cross over but mainly deal with either plumbing or process piping which includes chemical, petrochem, chilled, hot water, steam and medical. EPDM verses Buna N . EP is a higher grade gasket than BN is more of a standard grade. They do sell EPDM gaskets for dia unions separately.

 

[Mliu]

Adding strength to a system or improving a design feature doesn't put you in any liability for things failing downline.

And how would one PROVE to the property manager or building owner that you improved upon the design that was stamped by the original design engineers and approved by the AHJ? Your argument sounds great in theory, but that won't absolve you of financial (and possibly legal) liability if anything goes wrong.

The fact that the original dielectric union leaked apparently adds no value to your judgment on this issue? It was probably the original contractor's fault.

As I stated, the original dilectric union functioned without failure for 50 years. So your sarcastic comment about the original installation contractor falls flat. If the replacement dielectric union survives another 50 years without leaking, I'd consider that a successful repair. Who knows if this building will even be around 50 years from now? I certainly won't be.

 

[John Gayewski]

And how would one PROVE to the property manager or building owner that you improved upon the design that was stamped by the original design engineers and approved by the AHJ? Your argument sounds great in theory, but that won't absolve you of financial (and possibly legal) liability if anything goes wrong.

Removing a previous point of failure and creating a stronger joint is proof in and of itself.

50 years is a long time, it's almost as if the weak point in the original design was the dielectric union... Almost like eliminating it would improve the design since the rest of the system is running, and that part failed.

I think your looking past the obvious to find logic where there's none.

 

[John Gayewski]

We could meet in the middle and you could get a dielectric nipple.

I realize your probably not up on the latest things going on, but almost no one uses dielectric unions anymore. Water heaters have dielectric nipples on them standard, and they have been a point of failure for so many years that a large percentage of tradesmen don't use them. A "go between" nipple of brass or stainless or dielectric nipple (less common) would be the common practice now.

 

[Breplum]

When school district specs insist on dielectric unions, I show these and tell them no dielectric unions or we walk off.

 

[Master Plumber Mark]

When school district specs insist on dielectric unions, I show these and tell them no dielectric unions or we walk off.

I totally agree with you...Dielectric unions suck.... I think they could have easily just installed a SS flex connector
on that situation and it would not have had the stress on the lines and it would have worked for decades.....

I have seen so much of this over the years..... I have found that SS flexible female connectors
seem to be the best option for water heaters and other issues...

basically the SS steel connectors are Dialectric on both ends of the fittings----

If you dont think this is true , could you please explain to me why it is not so??

You can see the nut and pipe have a plastic ring which breaks the ground ..just like a dialectric union does..
and the rubber grommet disconnects the line from the heater....

 

[Breplum]

I totally agree with you...Dielectric unions suck.... I think they could have easily just installed a SS flex connector
on that situation and it would not have had the stress on the lines and it would have worked for decades.....

I have seen so much of this over the years..... I have found that SS flexible female connectors
seem to be the best option for water heaters and other issues...

basically the SS steel connectors are Dialectric on both ends of the fittings----

If you dont think this is true , could you please explain to me why it is not so??

You can see the nut and pipe have a plastic ring which breaks the ground ..just like a dialectric union does..
and the rubber grommet disconnects the line from the heater....

We love stainless steel water heater flex. Use them on water main connections all the time inside an irrigation box. Around here in the East bay Hills of San Francisco Bay area the soil movement is such that simple connections crack from soil movement and using a water heater flex always solves the problem. Especially bad are long PVC underground water mains male adapters…those threads are guaranteed to break. Love that they’re available in 2”. Don’t know about boilers

 

[Master Plumber Mark]

We love stainless steel water heater flex. Use them on water main connections all the time inside an irrigation box. Around here in the East bay Hills of San Francisco Bay area the soil movement is such that simple connections crack from soil movement and using a water heater flex always solves the problem. Especially bad are long PVC underground water mains male adapters…those threads are guaranteed to break. Love that they’re available in 2”. Don’t know about boilers

I guess that you agree that those SS connectors are Dielectric too???

The SS connectors make short work out of a lot of tight situations and I have used them
when coming off a main incoming line up out of a slab floor with no wiggle room to work with

I thought that flex connectors were code in California on water heaters for both gas and water lines??
due to movement in the ground..

 

[John Gayewski]

I guess that you agree that those SS connectors are Dielectric too???

The SS connectors make short work out of a lot of tight situations and I have used them
when coming off a main incoming line up out of a slab floor with no wiggle room to work with

I thought that flex connectors were code in California on water heaters for both gas and water lines??
due to movement in the ground..

They aren't technically dielectric. They don't actually break the connection as the metal nut touches the metal connector which touches the water which touches the black iron pipe.

Being fully dielectric isn't that important if the connection is LESS conducive and MORE strong. The problem with dielectric unions is that the corrosion and electrolysis is super concentrated on any part of the galvanized metal that has any type knick in it. So if there are any exposed threads in the union (which there always are) the corrosion focuses it's action there. It's mostly the oxygen in hot water systems that make dielectric unions really bad. Oxygen which isn't present in boiler systems.

The gaskets and weakness of those connections are what's mainly bad here.

They make dielectric nipples in any size for this.