Looking for Advice/Experience on Sch 80 PVC Glycol System

[DecoctionMash]

Sages of ProBrewer,

We have the misfortune of having a sch 80 pvc glycol system. I constantly get leaks at the NPT connections with my tanks and pumps. Any recommendations on thread sealants for a pvc glycol system?
I am also looking for better slip-connection pvc glue if anyone has anythings dependable.

Thanks for your time,

Cole Brown
Eagle Creek Brewing Company
Statesboro, GA
cole@eaglecreekbrewingco.com

[Starcat]

PVC Science

80 is unnecessary, 40 will work just fine.
Leaks as you are describing should be rare. If this keeps happening then your fitting Technique is off.
I use Weld On 705 because its clear and makes a cleaner job. There are all manner of PVC glue systems out there. I have used other specific types in Farm and Ranch settings where the duty is somewhat different.
There has been some discussion on the forum about differential expansion of stainless to plastic fittings, with the idea being that you are better off with a MALE plastic to a Female Stainless fitting when possible, as this connection is tighter when cold, where as the converse is true when those fittings are reversed.
With this being said, you can still get leak free connections regardless if you are very careful about assembly. Also if you have never fit much PVC, it helps to watch someone who is really good at it, and you will know what I mean by watching them fit a big job. I worked on a Ranch water system with a savvy Farm Boss where we were running both surface water treatment and field irrigation. Its was a golden learning experience. A pro will get leak free joints that are all very plumb, level, and square.....and dimensionally they will be very accurate with their runs. Artful.
Its critical how the primer and the glue is applied and so is drying time. Drying time varies with temperature, pipe size and if its open to air or not. There are charts that map this out.
ON the MPT and FPT connections, Rector Seal #7 is rated for Glycol. You can use this compound AND thread seal tape for a leak free connection when mating PVC to SS.
The Blue Monster tape is the best I have found for this purpose while the real thick pink styles do not work as well. The thread fitting them cannot be too loose or too tight.
Its a finesse that has to be learned. Your pumps need to be securely mounted and sometimes some flex connections may be indicated. I do not need any in this plant and we have a total of 3 chillers, 6 pumps, and interconnected piping.

All the best.

[dast]

Hi Cole,
These are the problems:
The lowest media temperature you can use for PVC is 32F and you are probably running your system at 25-28F. PVC get extremly brittle at low temperature. Here is a link to a video that shows the behavior of COOL-FIT ABS and PVC at 23F (-5C) http://www.youtube.com/watch?v=D8C_gZls6v8
PVC are not chemical resistant to propylene glycol. Propylene glycol is a possible ESC agent. Environmental Stress Cracking (ESC) is a mechanism by which an incompatible chemical achives an extremely localized weaking at the surface of the material which permits propagation of a crack.
This together with using a plastic thread together with a metal thread were you get different behavior (expansion & conraction factor) when the temperature change creates huge problems.
You also have a lot mechanical stress at this location.
We always recommend to use metal to metal threads if possible.

Georg Fischer is one of the biggest producer of PVC plastic piping systems in the world and we also invented the gap filling solvent cement for PVC for way over 50 years ago. Our company is 212 years old and produces over 18 different types of plastic piping systems.

Please don't hesitate to contact me if you have any questions.

Cheers

Dan Strömberg
Cooling Market Segment Manager
Georg Fischer LLC
Phone: +1 714 368 4196
Fax: +1 714 368 4197
Mobile: +1 951 642 2339
Dan.Stromberg@georgfischer.com

GF Piping Systems
2882 Dow Avenue, Tustin, CA. 92780
United States

https://www.gfps.com/us

[TGTimm]

Parts of our sch.80 glycol system have been in continuous use since 1997 without problems. Sch.40 might work just as well, but considering the costs and consequences of breakage, sch.80 makes good sense. As pointed out above, PVC does get brittle at typical brewery glycol temperatures.

Careful prep of the slip fittings is critical. Use a Scotch-brite pad to remove all the surface glaze from both the pipe end and the fitting. We use Weld-on 711 glue and a good quality, fresh primer. Whenever possible, the pipe or fitting should be rotated about 90-180 deg. when gluing up. Obviously, this isn't always possible, but it does result in a more reliable join.

Male PVC-female metal pipe threads--always! In addition to the differential CoEs, it's far too easy to crack a PVC FPT fitting by slightly overtightening the metal MPT fitting--which may not show up until the fitting has undergone numerous cycles. Our local suppliers won't even sell FPT fittings in sch.80 PVC for this reason. We use Chesterton Gold-end tape and paste on our threaded fittings (belt and suspenders), and have had an excellent record with them.

If I were plumbing a new brewery, I'd probably go with an ABS system like Cool-fit or possibly PEX. Insulating the lines is critical, and the insulation must be glued on so it's as nearly air-tight as possible--a pre-insulated system would be ideal, and would likely pay for itself in time saved insulating.

[BrewinLou]

Half our header is from 1996 and is Sched 40. I have had exactly one stress fracture in all that time. One of our solenoids hammers pretty hard as well, shakes the whole header. Yes in a perfect world I would love to replace it all with Cool Fit or another abs product.
If you go pvc as was said, insulate it well, and I would get some JACKETING SARAN 560 35.5" X 250' (740 SF/RL) for vapor barrier. It is like stretch film but much thicker, and wrap it over all your insulation.