Liebert cond tube repair

[mixsit]

I am hoping for some advice and opinion on options for a leak repair. This one is at the tube sheet of the return loop end (not the inlet/outlet header end) of a 4-fan air cooled unit.
Liebert offers a repair kit that consists of a 14' roll of tube that inserts into the full length of a damaged tube, and an assortment of replacement 180's and such. The instructions show cutting into and re-stubbing both ends regardless of which single end-leak it addresses.

Now as there is only this one trouble spot, and it happens to be a fairly accessible bottom row I was considering this option; I believe I can cut out the tube sheet around the tube and enough fins to allow brazing access, then insert just several inches of the repair tube and braze that to the exiting tube end and to the new 180' loop.
The worry is it's not a repair I've done very often through my years.
I can see upsides being;
-Not cutting into the end that is not leaking and which has more vibration (although light vibration as this is a remote condenser), inserting the inner tube the full length (yikes!), potentially a less expensive repair.
Down sides;
I have seen tube repairs with new cracks that follow up into the coil past the brazed repair spot. But I would associate that with compressor or more vigorous gas pulsation, and this plan has the reinforcing inside tube (clean and de-burred) well in to where the fins would remain.

Any best educated guesses out there?
Thanks ahead- And Merry Christmas out there! :patriot:
Wayne

[ispip]

I just repaired a leak in the same spot last week, I just cut the tube sheet end but taking a drill bit and drilling holes all the way around and took a pair of snips and snipped the little metal between the holes, a friend of mine used a dremal tool to do the same job. Just becareful because I have hit the tube with the drill bit end and it made another hole. Then I took and cut out the fins to get them out of the way. After all that I just laid some 15% down all the way around. Hope this helps

[mixsit]

... After all that I just laid some 15% down all the way around. Hope this helps
Just over the hole then? I've done that (damned-easy-to-melt-tube too!)
Yeah, I'm still kinda liking the in-tube idea but which is new to me though.
Damm, up to late again. :couchhide:

[The Doctor]

I like your idea better than the repair kit. Having repaired more than a few Liebert discharge line elbows at the compressor, also fittings at the receiver and such, and having repaired more CHOO_CHOO discharge leaks at the tube sheet, ...well, as Rocky would say, "Go for it."

Having said that, you could call tech support maybe and see if they have any syllables to mumble on the virtues of the repair kit, and then factor that into the equation.

[mark_ballard]

I have used dremel with flex shaft to get some tube sheets out of the way before. Use some 40% silver and it won't crack on you after.

[Randy S.]

I made a similar repair on a Carrier mini boxcar last summer. No kit available.

I used a Dremel tool to cut out enough of the end sheet to get brazing access.
Some long pointy scissors to remove enough fins to work.
Butt-ugly, but it worked and survived record heat.

[ispip]

Just keep in mind if you use that tube repair kit you are lowering the efficiency of heat transfer for that whole tube plus your making 4 braze joints. This kit was intended for use when you have leaks in the middle of the condenser and you don't want to cut out all those fins to get to it. If you use a low flame you will not burn threw or use that 55% flux coated rod. I have not had any trouble with 15% cracking but i have heard it can. Any way good luck to you.

[ispip]

[QUOTE=The Doctor;5333752]I like your idea better than the repair kit. Having repaired more than a few Liebert discharge line elbows at the compressor, also fittings at the receiver and such, and having repaired more CHOO_CHOO discharge leaks at the tube sheet, ...well, as Rocky would say, "Go for it."

On the Lieberts it is REAL important that you tighten the bolts down on the compressor so they are snug to the compressor but the washer can still spin. If you have to much play it will let the compressor rock to much on pumpdown and start up. Also on older units check your discharge tube clamps because they wear threw that orange rubber insulater.

[dilky]

lieberts leaks at tube sheets are common, i use a oxy acet torch, melt metal away from leak then repair leak be gentle also i use silver solder it flows better than silfoss. thats the way i do it good luck.

[mixsit]

Thanks a bunch guys for the back-up. I've decided to go ahead with silver solder on the leak, and I'll have the tube kit there as plan-B. They have about thirty of these units and if I don't need the kit it'll be fine to have at the site. The thing's only about $40.

Cheers
Keep it safe
Wayne

[JRINJAX]

lieberts leaks at tube sheets are common, i use a oxy acet torch, melt metal away from leak then repair leak be gentle also i use silver solder it flows better than silfoss. thats the way i do it good luck.Same here. We then paint the steel and copper at the repair with cold galvanize spray to stop corrosion.

[mixsit]

.. i use a oxy acet torch, melt metal away from leak then repair leak be gentle also i use silver solder it flows better than silfoss. thats the way i do it good luck.Do you mean melt the steel sheet away?

[Domcort]

Do you mean melt the steel sheet away?

I think he means melt away from the sheet metal, regardless you will be fine as the others stated use a drill bit / dremel and go around the tube to an then cut away the metal so you can access your leak if needed.

I had a condenser fan motor break and had to repair the first and second row of tubes, due to damage from the motor falling into the coil while operating, destroyed the blade and had ruptured the circuit that was in operation. I had to remove very carefully about a 4" x 8" area of the fins to do the repairs, no problems just take you time and if you have a very small tip for your torch that will work the best, it did for me.

Hope this helps,

[dilky]

are these lee temps ? its a common problem on these units with head masters constant throttling to maintain head pressure vibration eliminators help and securing discharge lines properly dont see this alot with fan speed units i know opinions vary, but this as been my experience with these good luck after the first one you will get better.

[dilky]

oh i just saw your post, yes its easy i melt away around the leak after you do that i pull away the weakened metal with long nose pliers thus all thats left is the copper i guess a dremmel would work as well but i like the torch its very easy yuo can see the metal melt away ive repaired quite a few , see what method works best for you , jump right in you can do it but remember i use silver solder only tube sheet copper is thin ,just like repairing a hot water coil split good luck pal and have confidence in yourself youll see.

[mixsit]

I was considering the rather large temp diff between melting steel and disappearing copper..
These are the fan-speed units btw (you know, with the 'self destructing motor bearings.. But that's another thread..

[JRINJAX]

I was considering the rather large temp diff between melting steel and disappearing copper..
These are the fan-speed units btw (you know, with the 'self destructing motor bearings.. But that's another thread..

By using a 00 torch tip and pointing the sharp-coned flame away from the tube the steel disappears and the copper [which doesn't get that hot] stays just like Dilky suggested. I have repaired several hundred of them with only a half dozen failures. Be sure to cold galvanize after it passes the leak check.

[dilky]

i disagree the p66 motor is a single phase motor made for this application also only a ball bearing motor no sleave bearings the others are 3 phase. if your losing motor bearings figure it out bad motors dont cause leaks why does everyone on this site disagree with any help given?how does a leak turn into a motor failure ?im sorry but honestly i dont get it a tube sheetleak is easy . never needed a dremmel or all of these tools to me its a simple fix honestly these are the way i do it , i mean no harm cmon guys all of us mean well and im here to help not hurt also when i had this problem it was my way or noway .take care you guys.

[soonera/c]

X2 on torching the tube sheet, easy to do and I have not had a problem yet. It's strange that molten steel can fall on the copper and not melt it. I guess the copper just dissapates the heat to quick.

[Pneuma]

steel melts aroound 1500 degrees, copper melts at about 2000 degrees

[mixsit]

Thank you again.
I came up with this;
http://www.engineersedge.com/properties_of_metals.htm , copper about 1975'F, steel 2575. But I was just going seat of the pants- recalling steel being quite a bit brighter when it goes. Good to know you can get away with it in spite of it.
Dilky I never said the motors had anything to do with the leak. My dig' was referring to the single-phase motors specifically though.

if your losing motor bearings figure it out
I'm pretty sure they have. They tend to cook the grease in the bearings.
There's a new p66 controller that looks to improve on that. (Love to have it on the lot of them but.. $$$ naturally..
:patriot:

[dilky]

I THINK ITS ALUMINNUM NOT STEEL .but i always burn around it carefully then remove the residual with long nose, because the copper is thin trial and error is important for confidence. you will see i have never lost one yet i think you said it best granpa was a vet and fitter ? its in you pal

[dilky]

your so right the metal turns bright red . some times i forget how i was but as my brazing skills improved came condfidence being from a cold climate and a lot of split coils i forget that some of us live elsewhere.