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Wyome
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We have to replace some underground conduit. 1" pvc coated grc. To fuel dispensers. Veeder Root level sensors. They have been having trouble with these since they installed them. They have decided that the conduit is sucking in water from some where. Then they theorize that the water freezes and pulls apart, breaking the wire in the process. Today he said he wants this new conduit to never have water in it again, thereby stopping this problem. I looked at the original installation, where I could. It looks proper. All the joints that I could see had the coated coupling. Someone used a blue thread sealer at each joint. Is there any way to prevent ground water from entering at the couplings? I haven't seen any product that targets this problem. Some sort of tape?
 

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The blue sealant is from the factory.
You will never stop the water with tapered threads on the conduit and straight threads on the couplings.

I would use PVC cement on the rubber boots that overlap the conduit on the couplings. That might help.
 

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I had a problem with antifreeze leaking out of screw top immersion calrod heaters so I used some permatex threadlock red.

http://www.all-spec.com/products/27150.html?gclid=CKGF-r2Uxb0CFchQ7AodiXcA-Q

It's not cheap, but the stuff works wonder for my applications. I use it for the immersion heaters and on bolts that hold a turbo in place that reaches 1000ºf.

Also, there might be an epoxy that can waterproof that conduit. I haven't looked into it but I did use epoxy for a somewhat similar application, but I didn't have to 100% waterproof it.
 

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te12co2w said:
We have to replace some underground conduit. 1" pvc coated grc. To fuel dispensers. Veeder Root level sensors. They have been having trouble with these since they installed them. They have decided that the conduit is sucking in water from some where. Then they theorize that the water freezes and pulls apart, breaking the wire in the process. Today he said he wants this new conduit to never have water in it again, thereby stopping this problem. I looked at the original installation, where I could. It looks proper. All the joints that I could see had the coated coupling. Someone used a blue thread sealer at each joint. Is there any way to prevent ground water from entering at the couplings? I haven't seen any product that targets this problem. Some sort of tape?
I don't care how much you seal a underground conduit it will get water in it over time. Condensation is the big culprit here.
Wide temp swings and you get water.
The utility companies now want PVC rigid from rd to meter, problem with this idea is water gets in and stays in.
IMO your better of giving it a place to drain off.
 

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once again, use tec cable.
no waterr will get in that.
you can run that s:censored: anywhere:thumbsup:
 

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Although sometimes it can be cheaper, depending on the system to pull in up sized, tougher cable.
 

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Man I am going to remember that stuff.
I looked at it for a fiber job, but we didn't try it. As I recall you need a small high pressure hose that you push in the raceway and as the gel is pumped into the raceway, you pull the hose back.

I expect it would would for power and signal conductors, but don't think it is listed or marketed for those uses.
 

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once again, use tec cable.
no waterr will get in that.
you can run that s:censored: anywhere:thumbsup:
I've replaced cables and when they came off the high line, the water POURED out them.. Depends on how they are terminated too...

One thing we did, but it was in 6" conduits under a road crossing that we pulled cable through was to drill a couple of holes in the bottom of the 90s.. Then when the water got in, it could drain out...
 

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My mentor worked for an engineering firm involved in a lot of municipal projects. He said water got in every type of conduit. I was always of a similar mind that it is more important that it is able to drain. If freezing is the problem consider burying it below the frost line.
 

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This is a problem I've never run into. Above ground, the conduits should be draining or ice is the least of the worries, underground I can only assume that they've always been below the frost line because I would never expect an underground conduit to be dry.
 

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Big John said:
This is a problem I've never run into. Above ground, the conduits should be draining or ice is the least of the worries, underground I can only assume that they've always been below the frost line because I would never expect an underground conduit to be dry.
. The only time I've experienced this was in new construction on small branch conduit slab work . Either slab on grade ( dirt , crushed stone , concrete ) , or elevated deck slabs ( pan decking , wire mesh , concrete ) , these small conduits aren't usually required to be very deep , hence the water in them freezes . We had extremely low temperatures that winter , so pulling underground branch was a problem , lol ! Luckily , it was a 2 year project , so lots of other stuff to do until the thaw .
 

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This is a problem I've never run into. Above ground, the conduits should be draining or ice is the least of the worries, underground I can only assume that they've always been below the frost line because I would never expect an underground conduit to be dry.
It is very rare to see raceways installed below the frost line around here. We have replaced the conductors in a same parking a lot a couple of times and I am sure the conductors have been damaged by the pressure from the ice. This was a rigid conduit installation. If you are not below the frost line, the best installation would be a cable wiring method and the next would be PVC conduit that is not concrete encased.

I had this issue with my underground phone line at my house. I live in an overhead service area, but wanted the phone underground. I had rigid conduit stubbed up at the pole and at the house with PCV in between. The phone company gave me some of their 3 pair underground cable with the metal shield. The winter the phone went out and the phone company put a temporary cable on the ground. When I worked on it the next spring, I found the cable had been completely pulled apart. When I fixed it, I drilled holes in the 90s for drainage and have never had the problem again...and that was about 30 years ago.
 
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