Bulk Milk Tank Internal Leak

[GenesisRefrig]

I have a small dairy farmer who has a refrigerant leak in his bulk tank. This is a short coupled system and there are NO LEAKS in the condensing unit or piping to the bulk tank.

Against my better judgement, I put in a can of A/C Easy Seal to try to fix the leak, and it didn't work.

Does anyone have advice on how to locate an internal leak in the bulk tank, and how to cut open the shell to repair it? Also, how do I make it look good after repairing the leak?

Any advice would be greatly appreciated.

Steve,
Genesis Refrigeration

[teddy bear]

What part of the country are you in? What is the brand and size of cooler? There techs out there that specialize in this type of repair.
I will follow with a phone number.
Regards TB

[barbar]

Before you look for the leak, please confirm that the leak is within the vat.
Disconnect all piping and pressure the vat circuit only (dry nitrogen), depending upon the make, the max pressure should be 10Bar (150psig)
leave for a period. If the pressure drops very slightly, then finding the leak without ripping of the all insulation skin, will be almost impossible.
If a drops quite a bit, then you could use a sonic tester to locate the vicinity of the leak, then remove insulation around that area.
BEST of LUCK

[maxster]

even a deep vac test with a micron/welsh pump will ace the tank out if it does below 5000 and keeps dropping over night.. beats humping nitros as a first step... NOTE: if you can't pull below 10K microns there is a leak with anything below 5K being moisture or in your case MILK!!

[GenesisRefrig]

Thanks for the replies so far. We are located in Northern MN. I have of course isolated the tank and verified an internal leak. I'm just looking for a procedure to find it and to access it. The tank is seamless stainless steel both inside and out. I'm guessing if I find the leak location, I'll have to cut an access hole in the stainless?

[maxster]

color trace with nitro to get a general area of the leak..soorry for the micron crap if your on that side of the system with it narrowed down on the cooler side

[teddy bear]

Thanks for the replies so far. We are located in Northern MN. I have of course isolated the tank and verified an internal leak. I'm just looking for a procedure to find it and to access it. The tank is seamless stainless steel both inside and out. I'm guessing if I find the leak location, I'll have to cut an access hole in the stainless?

Typically, techs use stythescope on the inside of the tank with the tank under pressure <250 psi. By listening on the inside surface of the tank, the leak is located. Cut a square foot acces hole on the outside with a small cutoff wheel. Tig weld the leak area if stainless steel (most are). Brand helps because they have traditional areas of leaking. Occasionally the load supporting channel may be involved and the channel may also cutout. Usually the refrigerant supply or returns are involved. Also tig the cut out access back and polish. Better contact techs who do this for a living.
Regards TB

[GenesisRefrig]

TB,

Thank you so much. This is exactly the info I was looking for. Again, thanks.

Steve

[monkeyspanners]

Done a few of these, i get a local stainless steel tig welder to fix them for me, he used to work for one of the tank manufacturers here.

https://www.youtube.com/watch?v=5e3wC8frIfo


One thing i have learned is the weight of milk can seal a leak 100%, it needs to be empty to be sure or left for a few days when it will have been emptied etc.

https://www.youtube.com/watch?v=LsgfRg0B8zw

Latest one,

https://www.youtube.com/watch?v=8kmm_Tcim6w

Check the oil level in the compressor as they can loose a lot in a short time with this sort of leak.

[refrepairman]

I have found a leak in a surge brand tank a few years back. I used the stethoscope and curt the hole with a cut off wheel. I also had a local guy with a rig welder do th repair. This tank leaked on the evap. Plate on the spot welds. It was pitted. Problem was with this tank, it had another leak two years later in another spot weld. Then last year the milk hauler forgot to vent the tank and sucked it down. Lucky for the farmer as the milk company's insurance paid the 80k for a new tank. Good luck!

[teddy bear]

I have found a leak in a surge brand tank a few years back. I used the stethoscope and curt the hole with a cut off wheel. I also had a local guy with a rig welder do th repair. This tank leaked on the evap. Plate on the spot welds. It was pitted. Problem was with this tank, it had another leak two years later in another spot weld. Then last year the milk hauler forgot to vent the tank and sucked it down. Lucky for the farmer as the milk company's insurance paid the 80k for a new tank. Good luck!

You got to love insurance companies buying bulk coolers.
Regards TB

[Swampy1234]

Hey did you find the leak , I find you need to charge with nitrogen to at least 15 bar , always make sure you do it when take is empty , if you really struggling get hot wash on the go and see the gauge drop specialy on fullwood Paco , I'll weld 3or 4 of these tanks every wk - Dari kool , muller Paco , laval ,

[GenesisRefrig]

Just wanted to bring an update to the original post. We located the area where the tank was leaking. Cut an access in the outer shell and hired a tig welder to fix about a 1/4 inch crack in the cooling jacket on the bottom of the tank.

The welder worked and worked and worked. The more he welded the more the leak opened up. He said the material was very thin. Finally, he got what looked like a good weld (the bead ended up being over 1 square inch. Put pressure on the tank, and found about 5 leaks where the weld bead interfaces with the jacket.

The welder we hired has lots of experience working on tanks of all kinds and of all materials, but I'm a little concerned that he keeps melting through the jacket.

I've used RedEpoxY from Highside Chemicals in the past with 100% success. I'm thinking about trying the RedEpoxY on the pinholes rather than calling the welder back. Any thoughts?

[monkeyspanners]

I doubt the red epoxy would work long term, there is a fair bit of expansion ans contraction when the tank is washed out with hot water, plus some flexing under the weight of milk.

I've seen problems due to compressor oil trapped between the plates, the heat from welding causes vapours which will blow holes in the weld.
When we had this trouble the welder got us to blow through the evaporator with some nitrogen to move the oil away, you need to get a bit of pressure in it and then release it all of a sudden such as blocking the other open pipe with a rag or a ball valve would be better (be very careful, ppe etc) We have also had to vacuum the evaporator in the past to boil off trapped refrigerant. Make sure the evaporator is vented when welding.
The welder will need to use different amperages depending on if he is welding near a spotweld when the metal is thicker or on the bubble part of the plate. Good luck!

[teddy bear]

Some flush the plate with a solvent to remove oil. In the old days we use R11 recirculated through the plate. Followed with nitrogen blow out.
Regards TB