Better way?

[Dr Duke]

So this kinda of relates to another post i started asking about HDPE, innderduct is what it's called around here, and rigid metal conduit couplings.
Here in the wet valley of ND I constantly come across water in conduits. This becomes a big problem when winter hits and the temps get COLD. I have had, I think, four calls this winter for broken probes wires and one broken submersible wire at gas stations. Yes you can pull new wire in the spring, but it is a bad deal nonetheless. Managers hate sticking the tanks for deliveries.
This post is asking if I'm dreaming or not. I am imagining using some type of continuous conduit, like "HDPE innerduct" and then changing over to rigid on either end. This continuous run would alleviate any concern for water intrusion, except for the changeover, which can't be much worse than using an "fa" and pvc. I am thinking may very well be faster to install as well. Just pull it off the big reel. Or even some type of flex that could be laid in, in the same fashion.
Is this something within reach, or am I dreaming? Just wanting to find a better more efficient way.

 

[Cow]

We've used it a fair amount, I'm starting to like it more and more.

It works well for long runs, a month ago myself and another guy were able to lay 3750' in 3 hours between six vaults. PVC can't even come close to touching HDPE in labor savings on those long runs. I'm not sure how well it'd work in other situations though, longs runs are great, a bunch of little runs for underslab work or similar, I'm not sure yet, as I haven't tried it.

I know I do like HDPE because you don't have joints every 10-20' like PVC, that right there helps keep the conduit cleaner since there is less chance for dirt and rocks to get in the conduit.

The downsides to HDPE that I've found:

1. big reels, it takes a forklift to move them around.
2. you need a way to spool them off. A big spooler?
3. shur lock II fittings are considerably more expensive than a standard pvc coupling
4. I haven't verified it, but I don't think you can heat it to bend it.
5. if there are a couple guys running the same size HDPE, you may only have one big reel to pull off of. Might be a problem for productivity, waiting around, versus everyone having their own pile of pvc to grab sticks out of.

 

[Dr Duke]

Very true. Just something that came to mind anyway. I know you can bury "sealtight", but that'd be kinda cheesy. And I'm pretty sure the connectors are not listed for direct burial anyway. I honestly think the worst link in a pvc/rmc raceway is the change over between them. I wish someone made a long bell "fa" or "ta". I'm not sure if there are any other options. I suppose 20' sticks of pvc would help a bit.
And I've tried to heat the HDPE ducts before, and they just crush when trying to bend it.

 

[Cow]

Very true. Just something that came to mind anyway. I know you can bury "sealtight", but that'd be kinda cheesy. And I'm pretty sure the connectors are not listed for direct burial anyway. I honestly think the worst link in a pvc/rmc raceway is the change over between them. I wish someone made a long bell "fa" or "ta". I'm not sure if there are any other options. I suppose 20' sticks of pvc would help a bit.
And I've tried to heat the HDPE ducts before, and they just crush when trying to bend it.

I agree with the long FA. That is truly the weak point. We just found out we lost an underslab conduit yesterday right at the 90, which I'm sure is because the pvc pulled out of the FA. Fortunately we're in a building, so, overhead to the rescue! We do A LOT of pvc underground with transitions to rigid stubups. We try not to use any pvc couplings for the same reason, they always seem to pull out if they get handled or bumped to much.

Just like you're thinking, we might try HDPE for some of this work, but not having a listed transition fitting for 3/4", which is our most common size, is a real buzzkill.

 

[mopowr steve]

I've been told that if you would actually use primer before glueing, like plumbing; most of those issues go away.
Unless the joints are just to loose to begin with or condensation is your real culprit.

 

[Dr Duke]

Could definitely try using the primer. Can't stand how short the bells are though on the "fa's". And "ta's" aren't much different. As Cow said, just a little wiggling can accidentally loosen things up. I'm just trying to thing if a different way to do thing all together. Especially for not getting water in the pipes. At least trying to minimize it anyway.

Maybe if a guy were to fab them up out of the trench, let dry, the brush on some rubber sealant over the pvc/rmc joint.....

 

[ActionDave]

Could definitely try using the primer. Can't stand how short the bells are though on the "fa's". And "ta's" aren't much different. As Cow said, just a little wiggling can accidentally loosen things up. I'm just trying to thing if a different way to do thing all together. Especially for not getting water in the pipes. At least trying to minimize it anyway.

Maybe if a guy were to fab them up out of the trench, let dry, the brush on some rubber sealant over the pvc/rmc joint.....

You are never not going to have water in an underground conduit.

 

[iwire]

You are never not going to have water in an underground conduit.

That has been my experience.

If not from direct intrusion it will collect from humidity condensing if there is any airflow at all and there almost always is if a conduit runs from inside to outside a building.

 

[Dr Duke]

This would be completely isolated to outside.

On on the bright side, these broken probe wires and power wires have been from before I started doing gas station installs. But I was trying to think of a way I could do an even better job on the installs that I do.