stop-leak for threaded connection on NH3?

[Buckiesr]

Has anyone ever found a way to stop an small leaking pipe thread leak on a liquid, suction ,or hot gas, pipe? I have a seeping tiny leak that is just enough to alarm everyone in the area every time the drum trap empties. the leaking thread is on an isolation valve between the trap and the Condensing Pressure Receiver The bottom thread is not so bad but the top will require an complete plant wide shutdown. Maybe I need that stuff they show in the TV that stops all kinds of leaks. My luck it would create an atom bomb when it comes in contact with liquid ammonia.

Buckiesr
IL, USA

[PRESS]

Hi!

I personally think it is worth it to carryout a plant shut down for that small leak to repair it, given the toxicity and safetey levels requirement NH3 use and handling. What if the stop leak solution does not work and your fears happen. It is also good workmamship to repair leaks as a permanent soution compared to attempting solutions which no one has really used before. I personally would say do it that old fashioned way.

[Andy]

Has anyone ever found a way to stop an small leaking pipe thread leak on a liquid, suction ,or hot gas, pipe? I have a seeping tiny leak that is just enough to alarm everyone in the area every time the drum trap empties. the leaking thread is on an isolation valve between the trap and the Condensing Pressure Receiver The bottom thread is not so bad but the top will require an complete plant wide shutdown. Maybe I need that stuff they show in the TV that stops all kinds of leaks. My luck it would create an atom bomb when it comes in contact with liquid ammonia.

Buckiesr
IL, USA

Hi Buckiesr


It is possible to pull down into a vacum, and change the fitting then. Tread tape is a bit light weight for ammonia, but if you use tread tape and boss white/stage or any sealer used on steam you will be fine.

Now be very careful and get your mate to control the compressor loading to acheive the vacum, and remember to purge the air at the condenser afterwards.

Quite safe if you do it correctly, even safer than trying to pump out a wet return or a liquid line with insulation on it.

Kind Regards Andy

[Buckiesr]

I know how to change it. What I want to know is if there is a temporary fix to plug a tiny annoying little leak until the planned shut-down. I have been in the industry for nearly forty years now. I can't believe someone hasn't come up with something to seal thread leaks, I will seal it either I will repair it with sealer but since this is a new install six months in service and has been leaking all along. We just found out where it was coming from. a leak under the insulation is like a natural gas leak under ground and a water leak in a flat roof, you find where it comes out but you have not clue where it is leaking, it might be an inch or a mile away from where it is leaking. We finally isolated the leak! yea! Now I have to fix it. Chances are very good that the reason it leaked from the start or nearly the start up is due to bad threads not the pipe sealant. It does appear they used Teflon tape, I prefer something more substantial for threaded pipe on ammonia but It was installed by licensed trained qualified Union Pipe-fitters. I will probably back weld it. However it will have to be scheduled over Christmas. So the crew will have to live with the smell until then. When I am reminded of a ammonia smell I normally respond by saying: "Aha! Nothing like the smell of ammonia first thing in the morning!" I have such a time with the fear of ammonia. Someone should have told the football and basketball coach that it is toxic when they used to break ammonia capsules under our noses when we were panting like a hot dog on the bench during a time out. What can I say I am an old dog. Seen so many changes over the years. I remember when we did not even know what an air monitor was and no one really knew how to use a draggier tube. PPE was a sign of a novice until it was pretty close to the IDHL point. I remember in the 70's standing at the bottom of the ladder keeping watch and fetching things for the other tech, and choking back gags and wiping tears from my eyes for hours while we silver soldered unit cooler leaks. Ammonia stinks, the fumes off of silver solder are poison and never leave your body or so I have been told. We have so much more safety awareness and tools to help us remain safe. So If I can encourage you a little, please use the equipment available to protect yourself. Thank you for all of your thoughts.
Buckiesr

[US Iceman]

My suggestion is one of two possibilities.

Either pull the system down into a vacuum and change the threaded parts out with new ones (so you can change it more quickly)

or,

Pull a vacuum and seal weld the joint. This is probably faster.

What do you want to bet that no one used a thread gauge on the threads before it was installed? Threading is such a simple operation it is getting unusual to find it done properly.

Personally I would not have used teflon tape. If they can't produce good threads on pipe, do you think they know there is a proper way to wrap tape on pipe threads?

[Buckiesr]

Hi!

I personally think it is worth it to carryout a plant shut down for that small leak to repair it, given the toxicity and safety levels requirement NH3 use and handling. What if the stop leak solution does not work and your fears happen. It is also good workmanship to repair leaks as a permanent solution compared to attempting solutions which no one has really used before. I personally would say do it that old fashioned way.

I hear you my friend, unfortunately, the decision to shut down the plant is not so easily obtained. Most USA plants operate on a 24 hour basis and nearly 365 days a week. Shutdowns for any reason other than an emergency, do not happen. a little stink is not even on the scale. The is a whiff of smell when the trap dumps, you can work in 30ppm for an eight hour period so a 3-10ppm on occasion is not to critical. I am a farm boy. I have side dressed farm ground with ammonia over the years using a tractor and an implement pulled behind the tractor, and a nurse tank full of liquid ammonia pulled behind that. When you put the implement into the ground you pull a knob and the ammonia valve opens injecting the ammonia into the ground, well most of it anyway. When you come to the end of the field, you push the knob back in to shut off the ammonia and pull the implement out of the ground so you can turn the tractor and what your pulling behind you, and move over so you can do it again the other direction next to where you just injected it on your last pass. The very first time I did this, the hired hand parked the tractor the night before and backed the tractor into a tree limb, knocking out the rear window of the tractor cab. So when I came to the end of the field, and pulled the implement out of the ground, the end of the ammonia stream would gas off into the air and into the tractor cab with me. I would be smothered at the end of every down wind pass. I finally started to shut off the ammonia before I came to the end of the field trying to time it so the ammonia would be all gone by the time I pulled it out of the ground. that way I get a cab full of dust but not ammonia/dust. I thought I was pretty clever until the corn was planted and started to grow, then you could see exactly where I shut off the ammonia and the last 25-30 yards of corn did not do well. So 20-30 yards of unfertilized corn every 40 feet all the way across 300 acres of corn, is a costly and not very easy to hide or explain. And I had to see it everyday all season long to remind me that it happened because I didn't want to smell the ammonia at the end of the field. What I learned was that when you are a part of a system, doing what will accomplish the systems goal, not what makes me feel comfortable. I can't say I never cut a corner or that I always kept the end result in my sights, but I never do it without seeing those yellow tinted sick looking corn rows at every other end turn around place in my mind. I think what I am saying is that when your refrigeration system is a part of the whole, the decisions that effect the system need to be made based upon a view of the entire operation and not just on one part of the system. I am aware of the dangers and risks related to the system I manage, and am completely honest with the other managers as to my feelings and risks and beliefs; but the decision to shut down is not made by me. I do appreciate your input. I value being reminded and considering all of the feedback I find on this sight. I always hear in my mind that, if it had been done right the first time, we wouldn't be having these issues. Where is the commissioner on this project? He should be dealing with this he approved it. In a perfect world maybe. We all have to work with what we have and what we are handed. Right? Thank you. Oh and I wanted to say something else. How will we come up with good ideas and fix-it ideas, shortcuts and tricks of the trade, unless some of us are the pioneers in experimenting and testing sound ideas? Best left to the experts? I am an expert in my fields. There are a lot of us out there so share your thoughts and discoveries with me. If it is not what you want on the thread send it private to me. Inquiring minds want to know! ! ! !
Buckiesr

[The Viking]

Most USA plants operate on a 24 hour basis and nearly 365 days a week.

You Yanks, always has to be bigger and better than everybody else.

My boss will only let me work 7 days a week.....

[Grizzly]

Buckiesr.
Back in the good old days before we adopted your National Passion for Suing everyone. Or should I say making Lawers rich and everyone elses life a Nightmare. Don't get me wrong I have adored my visits to America and love an awfull lot of your culture but litgation is not one of them.
THE FOLOWING IS NOT POLITIACALLY CORRECT .... BUT IT WILL GET YOU OUT OF THE S;;T!
I say this because I have seen or been party to,two methods used to temporarily repair leaking Steel Lines charged with ammonia.
The first repair was used very successfully as a temporary repair on a liquid balance line.
The pipework had corroded within it's saturated Insulation. Resulting in a highly pitted, rotten, rusty mess.
Take a large tub of 2 part resin putty... We used "Magic Putty" supplied by R.S. here in U.K. (sometimes refered to as a liquid metal!)
Select the nearest pipe size with a bore size matching the leaking pipes outer diameter.
Cut the pipe to length with a suitable overlap of the leaking area.
Cut the pipe straight down through the middle of it's length.
Apply generous amounts of premixed putty to the leaking pipe. Or if neccessary coat the repair pipe internal bore with the putty.
Place both halves of the larger pipe over the leaking area and Secure in place with "Jubillee Clips" ( You may know them as Hose Clamps?)
Not a pretty repair but very effective.
Alternatively you could coat the affected area (whilst it is not leaking) with the 2 part putty letting it set.
Either option will buy you a lot of time until you can effect a permanent repair.
Incidently I use a product called "Leak Lock" ( High Side Chemicals.INC GULFPORT MS.) On threaded joints.
Brilliant for all refrigerants.
Everyone should be aware the PTFE Tape can breakdown when in contact with some of the newer synthetic POE Oils.
Also in the past I have used a steady stream of water to repair small leaks ie. leaking valve stems.
Simply drissle the water as slowly as possible over the leak and sometimes the ice that forms. Will seal the leak with a plug of ice.
Yet another simple but very effective repair.
I hope this helps?
Grizzly
"How does an ammonia engineer breathe.. CAREFULLY"

[Brian_UK]

Another method of sealing a small leak in a threaded connection is the peening method.

Using a cold chisel or centre pop (point) and a hammer you can sometimes stop a small weep from a screwed fitting by hitting the leaking position to peen over the metal to create a mechanical seal.

This obviously is not ideal but is used quite frequently.

Also this firm may have something to offer...

http://www.cedagroup.com/content/rel...Leak_LORES.pdf

[NH3LVR]

Peening does work, at least on very small leaks in welds. I have never tried it on a threaded fitting.

A few thread sealants have been mentioned.
I use Teflon tape exclusively on NH3 relief valves. it has worked well in that application. I do not use it in a case where the pipe can move.
Rectorseal works well, although it has a setting time.
Expando is the best sealant for NH3. It has a set time but will not leak unless the pipe is moved. It is also very difficult to break loose to do repairs. Once a leak has developed and the Expando is broken you cannot seal it by further tightening.
I have tried Leak Lock on NH3. I know it works well for the ***** guys, but it has not performed well for me.
Now for one that is not in the books. On a troublesome fitting I apply Rectorseal, wrap it with a couple of turns of Teflon, and apply more Rectorseal.
(Yes, US Iceman, I am giving away secrets again) But I am out of the Bussiness now. (Mostly)
I am sure that this will drive the application engineers crazy, but it does work well.

[Grizzly]

Hi NH3LVR.
Thanks for your tips. The main problem we all have is some of the products we use are not Universal. I had not heard of either "rectorseal" or "expando".
You are correct in that "LEAK LOCK" does not allways work.
I am led to believe this is because it relies on compression forces within the fitting that is being sealed.
Therefore it is more successful on tapered thread fittings than parallel ones. I could of said this in my previous post. But I did not want to go on unnecessarily. You refer to giving away trade secrets. I personnally struggle with this one on the forum. "A little knowledge in the wrong hands is dangerous". True but we all had to start somewhere, I have spent years frightening younger less experianced Engineers with Ammonia Horror Stories.
But I feel it may be starting to backfire on us! The crap starting to be spouted about how dangerous the dredded ammonia is frightens me.
THE LATEST RULES AND REGS .. Coming out are being made by people who have listened to these stories 2nd or 3rd hand.
Is it not about time we started to prove that if used safely and correctly is a lot better than most of the alternatives.
Buckiesr I hope the posts are usefull?
NH3LVR why do you refer to process engineers not liking your post?
Grizzly
ps Several of the guys have refered to vaccuming the system. Have you guys experianced the same as me ... The plastic handle on a robinet pump becomes brittle and breaks up over time?

[NH3LVR]

The part about giving away secrets was a joke.
US Iceman was kidding me about a previous post where I shared a tip to start NH3 pumps when you have cavitation problems. It is hardly a secret, and the comment was in jest.

The application engineers I refer to are the folks who work at the companies that manufacture sealants. Tampering with their carefully concoted formulas is not recommended, or wise. I am not recommending anyone do this.

[US Iceman]

Is it not about time we started to prove that if used safely and correctly is a lot better than most of the alternatives.

Yes we should. The main problem when refrigerant safety discussions come up is they are mostly based on disinformation, emotions, and anecdotal evidence. The first part we should agree on is; all refrigerants are dangerous. Yes, even those so-called safe ones.

The horror stories are important as a teaching tool. Unfortunately, what happens after they have been passed down several times is they start to loose their basic facts. It's like a rumor. The more it is told the farther from reality it gets.

[hendry]

Peening does work, at least on very small leaks in welds. I have never tried it on a threaded fitting.

A few thread sealants have been mentioned.
I use Teflon tape exclusively on NH3 relief valves. it has worked well in that application. I do not use it in a case where the pipe can move.
Rectorseal works well, although it has a setting time.
Expando is the best sealant for NH3. It has a set time but will not leak unless the pipe is moved. It is also very difficult to break loose to do repairs. Once a leak has developed and the Expando is broken you cannot seal it by further tightening.
I have tried Leak Lock on NH3. I know it works well for the ***** guys, but it has not performed well for me.
Now for one that is not in the books. On a troublesome fitting I apply Rectorseal, wrap it with a couple of turns of Teflon, and apply more Rectorseal.
(Yes, US Iceman, I am giving away secrets again) But I am out of the Bussiness now. (Mostly)
I am sure that this will drive the application engineers crazy, but it does work well.

yes, we use leaklock (now they have Gold).
we use it often to make things right the 1st time.

we use it for both ammonia and other halocarbon aplication.

so far ... good! that's what I could says.

[Grizzly]

Has anyone ever found a way to stop an small leaking pipe thread leak on a liquid, suction ,or hot gas, pipe? I have a seeping tiny leak that is just enough to alarm everyone in the area every time the drum trap empties. the leaking thread is on an isolation valve between the trap and the Condensing Pressure Receiver The bottom thread is not so bad but the top will require an complete plant wide shutdown. Maybe I need that stuff they show in the TV that stops all kinds of leaks. My luck it would create an atom bomb when it comes in contact with liquid ammonia.

Buckiesr
IL, USA

Buckiesr.
How did you get on?
It would be nice to get an update.
Grizzly

[Buckiesr]

That is very helpful information. I had one of the welders back weld the valve top and bottom, It leaked, I pumped it down and he did it again, it still leaks a little. How many times does a person care to pump down the liquid line between the dump trap and the CPR? I am afraid I have to cut out the whole section and replace the valve and the pipe sections above and below the original leaks. I haven't been welding at all for nearly two years now so I thought the welders would do a better job. He was not skilled in welding in the confines we often have to work in. I think he was afraid of the sparks going down his neck also. I wish I could have read your reply before I had to do the job. Net time! I might have to do it on this one before it is over. Thanks again.