HDPE vs PVC Schedule 80

[W@ttson]

I have always specified PVC Schedule 80 for outdoor underground installations. Contractor is asking to use HDPE, would this substitution be inferior, equivalent, or superior?

Thank you

 

[kingpb]

I have always specified PVC Schedule 80 for outdoor underground installations. Contractor is asking to use HDPE, would this substitution be inferior, equivalent, or superior?

Thank you

You can get HDPE in Sch 80, so in that case the same. You need to make sure they are not substituting it with HDPE Sch 40.

 

[zbang]

HDPE is tougher than PVC* but not as rigid. For some applications, it's probably a better choice.

* we're allowed to shoot aerial display fireworks from HDPE tubes but not from PVC; it tends to shatter :thumbsdown:.

 

[W@ttson]

Hmm they are submitting it as an SDR value. I do see that there is a Sched 80 option but is Sched 80 HDPE equivalent to Sched 80 PVC?

You can get HDPE in Sch 80, so in that case the same. You need to make sure they are not substituting it with HDPE Sch 40.

 

[W@ttson]

If only I was dealing with such cool things as fireworks

HDPE is tougher than PVC* but not as rigid. For some applications, it's probably a better choice.

* we're allowed to shoot aerial display fireworks from HDPE tubes but not from PVC; it tends to shatter :thumbsdown:.

 

[petersonra]

I think the thing with HDPE is it is flexible enough that you can trench it and bury in one operation. You can also directional bore it.

I don't think there is all that much difference. It is underground where it is about as safe as it gets most of the time.

I don't think I would even worry all that much if they wanted to use schedule 40. But, I did not even know it came in schedule 40 and 80.

 

[steve66]

HDPE comes in long lengths on a coil or reel for boring or plowing into the ground.

I think I just read its only available as schedule 80 on a reel though. Something about the thinner wall on schedule 40 deforms too much.

 

[Cow]

I have always specified PVC Schedule 80 for outdoor underground installations. Contractor is asking to use HDPE, would this substitution be inferior, equivalent, or superior?

Thank you

Have them send you a cutsheet on the particular product they intend to use and verify the wall thickness is similar to what you're proposing.

We use a lot of Duraline sch. 40 UL listed HDPE on reels. Make sure they intend to use a UL listed product, because a lot of it is not. I know that because I have to specifically mention it when ordering or else I'd get HDPE without a listing.

Also, make sure they use a UL listed transition coupling from the HDPE over to pvc/rigid/etc before it exits the ground. We use Duraline Shur-Lock II's. Again, a lot of couplings aren't UL listed. I'm sure it's because a lot of this stuff is used for utilities and they work from their own rule books.

 

[gadfly56]

Have them send you a cutsheet on the particular product they intend to use and verify the wall thickness is similar to what you're proposing.

We use a lot of Duraline sch. 40 UL listed HDPE on reels. Make sure they intend to use a UL listed product, because a lot of it is not. I know that because I have to specifically mention it when ordering or else I'd get HDPE without a listing.

Also, make sure they use a UL listed transition coupling from the HDPE over to pvc/rigid/etc before it exits the ground. We use Duraline Shur-Lock II's. Again, a lot of couplings aren't UL listed. I'm sure it's because a lot of this stuff is used for utilities and they work from their own rule books.

Based on a technical sheet from Duraline and one from Harvel it looks like the nod goes to PVC.

 

[Carultch]

HDPE is tougher than PVC* but not as rigid. For some applications, it's probably a better choice.

* we're allowed to shoot aerial display fireworks from HDPE tubes but not from PVC; it tends to shatter :thumbsdown:.

This is important. What do you mean by tough and rigid?

 

[gadfly56]

This is important. What do you mean by tough and rigid?

HDPE will absorb impact energy by deforming, whereas once you pass a certain strain threshold PVC will shatter. The HDPE will usually return to its pre-impact shape depending on how much oomph! is behind the impact. It's a bit like the GM Saturn vehicles with the plastic side panels. Easier to deform, but they'd bounce back from a smack with a baseball bat where a metal side panel will deform permanently.

 

[W@ttson]

HDPE will absorb impact energy by deforming, whereas once you pass a certain strain threshold PVC will shatter. The HDPE will usually return to its pre-impact shape depending on how much oomph! is behind the impact. It's a bit like the GM Saturn vehicles with the plastic side panels. Easier to deform, but they'd bounce back from a smack with a baseball bat where a metal side panel will deform permanently.

OK so here is a summary of my investigation. I reached out to both manufacturers, the PVC - Schedule 80 that was already approved and the HDPE conduit that has been submitted. This is what I found:

PVC Schedule 80 Manufacturer: "We don't know too much about HDPE, we don't really see them as a direct competitor. We focus most of our literature on how PVC is better, lighter, quicker to install than metallic conduit."

HDPE Manufactuer: " HDPE is a superior product to PVC. A lot of people are updating their specifications and moving toward HDPE.

HDPE comes in continuous lengths. Less couplings and gluing. If you do need to couple there are special two part epoxies that need to be used to glue special HDPE couplings. There are also HDPE Shurlock couplings which are UL listed and can transition to just about any other conduit system. HDPE when laid in a trench is flexible enough to get around most obstacles. The one thing that is worse about HDPE is that it does have more of an expansion contraction issue than PVC. Though it being underground that should not be as much of an issue. HDPE can be installed at -40Def F while PVC gets very brittle at a little below freezing. Wall thickness is similar between PVC and HDPE and you can see how they compare, you can get a Schedule 80 HDPE conduit and that will actually be slightly thicker than the PVC schedule 80 conduit. Not all HDPE is UL listed though, only Schedule 40, Schedule 80, and SDR 13.5 HDPE can be UL listed. If you don't ask for it you will not get the UL listed one."

Since HDPE can only be installed underground, I don't see it having a worse contracts expansion properties much of an issue. It seems like there are some serious cost benefits to using HDPE duct and as it starts to get more accepted it will surpass PVC at least for all underground installations.

 

[gadfly56]

OK so here is a summary of my investigation. I reached out to both manufacturers, the PVC - Schedule 80 that was already approved and the HDPE conduit that has been submitted. This is what I found:

PVC Schedule 80 Manufacturer: "We don't know too much about HDPE, we don't really see them as a direct competitor. We focus most of our literature on how PVC is better, lighter, quicker to install than metallic conduit."

HDPE Manufactuer: " HDPE is a superior product to PVC. A lot of people are updating their specifications and moving toward HDPE.

HDPE comes in continuous lengths. Less couplings and gluing. If you do need to couple there are special two part epoxies that need to be used to glue special HDPE couplings. There are also HDPE Shurlock couplings which are UL listed and can transition to just about any other conduit system. HDPE when laid in a trench is flexible enough to get around most obstacles. The one thing that is worse about HDPE is that it does have more of an expansion contraction issue than PVC. Though it being underground that should not be as much of an issue. HDPE can be installed at -40Def F while PVC gets very brittle at a little below freezing. Wall thickness is similar between PVC and HDPE and you can see how they compare, you can get a Schedule 80 HDPE conduit and that will actually be slightly thicker than the PVC schedule 80 conduit. Not all HDPE is UL listed though, only Schedule 40, Schedule 80, and SDR 13.5 HDPE can be UL listed. If you don't ask for it you will not get the UL listed one."

Since HDPE can only be installed underground, I don't see it having a worse contracts expansion properties much of an issue. It seems like there are some serious cost benefits to using HDPE duct and as it starts to get more accepted it will surpass PVC at least for all underground installations.

I'm guessing that by the time you have bent over a trench gluing together 20 foot sticks of PVC for a 1000 foot run, you're real ready to look at HDPE.

 

[GoldDigger]

I'm guessing that by the time you have bent over a trench gluing together 20 foot sticks of PVC for a 1000 foot run, you're real ready to look at HDPE.

Especially with the built-in pull tape!
NEC says you cannot pull the wires before the conduit run is complete, but does not care about the pull tape.

 

[gadfly56]

Especially with the built-in pull tape!
NEC says you cannot pull the wires before the conduit run is complete, but does not care about the pull tape.

Really? Duraline will sell you the conduit with the conductors already in it.

 

[Cow]

Really? Duraline will sell you the conduit with the conductors already in it.

You're taking what Golddigger is saying out of context.

Cable-in-conduit is a premanufactured assembly from the factory, you know that, and it doesn't make what Golddigger said any less true.

 

[gadfly56]

You're taking what Golddigger is saying out of context.

Cable-in-conduit is a premanufactured assembly from the factory, you know that, and it doesn't make what Golddigger said any less true.

He said "with the built-in pull tape" which Duraline also offers and which I don't see how you get with 20 foot PVC sticks. I thought we were continuing the discussion of Duraline, not going back to PVC.

 

[Adamjamma]

The hdpe stuff has me looking... only have another two floors to build but, it looks like a lot less work to use. Still watching prices for my next trip to Jamaica. I hope to hear how others are faring with it in concrete... YouTube promos show it to be pretty good but they show a lot of things that don’t work..lol
like steel door frames

 

[gadfly56]

The hdpe stuff has me looking... only have another two floors to build but, it looks like a lot less work to use. Still watching prices for my next trip to Jamaica. I hope to hear how others are faring with it in concrete... YouTube promos show it to be pretty good but they show a lot of things that don’t work..lol
like steel door frames

Whatever you put in concrete, make sure it's tied down real good or you'll get an object lesson in buoyancy!

 

[Adamjamma]

Yeah, have seen drain pipes lift off because plumber said they don’t need tied.... I go through loads of baling wire and zip ties, depending on what it is... love the smell of concrete in the morning but hate it after lunch..lol...