SDR-21 or Schedule 40 PVC

[EddieWalker]

PVC Pipe

I did a little searching to educate myself and see how off base I was. This is a good link that explains it so I could understand what is what.

As for the black poly, I know there are several levels of pressure rating for it and that the higher the rating, the better it is, but that's not the problem. What happens is that the black poly doesn't handle movement very well and if there is any movement in the ground, it's just a matter of time until it fails. PEX is similar in appearances and cost, but designed and able to flex, expand and even freeze over and over again without failure. It's hasn't been around long enough to know this for sure or if it will last for decades in expansive soil, but from everything I've heard so far, it's pretty good stuff. If I was ever to think Black Poly was a good choice for something, I would definitely use PEX instead.

I have c900 to my house.

Eddie

 

[orezok]

SDR comes in 2 types and several different pressure levels. The SDR Eddie is referring to is probably SDR35 which is a non pressure sewer pipe.

SDR pressure pipe comes in ratings from 100PSI to 250PSI working pressure. The stuff carried at box stores is probably the low pressure stuff.

Prior to retiring I used to build schools. A high school may have 10 miles of irrigation pipe installed, most of which is pressurized by booster pumps running up to 100PSI.

Lines less than 2 1/2" were always schedule 80 PVC. Lines 3" and above were C900 with mechanical joint fittings. We used mechanical joints because as others have mentioned, the ground constantly moves.

Our long term failure rate was almost zero. I know that this is an expensive installation, but it is designed to last 50 years.

 

[speedbump]

I agree that Poly would be the best. I don't know what length rolls you can get in 2" as I haven't used Poly in over 30 years. I understand it comes in 200 psi, same as the SDR 21 that I use all the time. I have been using thin wall PVC for 30 years, only used primer once and have great luck with it. But in Florida, most of it is above ground. Poly might get squashed by a rock or other object if the trench isn't carefully backfilled, but it won't break. If you are going to use PVC, you will find that SCH 40 breaks quicker than SDR 21 will.

 

[SPIKER]

Up here we use at min the 160 PSI poly (which is much better than the old 1970's stuff which expanded in diameter a lot with pressure & could pull out of the ends.) The new stuff is very similar to PEX (cross linked polyethylene) and has very little shrinkage due to expansion. It is also much more flexible in trench if you have a poor or rocky soil to move it around underground rocks etc.

On the slip joint pipes these under movement in that run could stack up and end up having one of the joints pushed out under some conditions and at that you could have leaks every/any 10 or 20 feet section over your 1700 feet. Long term if you are connecting to chlorinated water not sure of the seal life under those conditions. These lines are somewhat new (I have not used them) many cities are in large diameter versions so much be somewhat good. That said the smaller diameter versions may end up with the absolute needs to make the trench flat and even spaced and surround the pipe with correct amount of correct sand. It would need a great deal of additional surface & trench prep and costs in materials & handling. Not sure how pressure testing them would work as under pressure they may want to PUSH (expand apart) and so would need fill over them and no way to be sure they were leak free?

Just as an FYI what I have done at my farm, using the 4" corrugated (solid not slotted/punched) field drain tile. I laid 160PSI black poly (cross-linked polyethylene potable water pipe) pulled it thru inside the tile. if/when I ever have to change it I'm hoping that I will only need to dig up the ends and slide out the pipe and put in new. However in past installs & current installs the line is ~4-feet deep around here for frost & I have never replaced a line due to it failing even in the 70's old black poly stuff. I have replaced frost free hydrants that had the poly at the bottom, due to the fittings breaking or hydrant getting run over/broken off from age/use. On both of those cases the poly was trimmed back a few inches and the NEW hydrants installed with a large Galvanized (upside down T for added support) and back up and running. The two I replaced was due to lack of proper support on the hydrant when originally installed (not sure when on both cases) & the previous person used plastic elbow fittings on/at the bottom. The wiggling of the hydrant using it opening/closing eventually broke the fitting the poly was OK.

No matter what you run be sure to install tracer wires and plastic tape a foot or so above the lines so you (most likely long down the road new owners) can locate the lines. also be sure to NOT have too many trees close to them. I would be afraid of issues with tree roots trying to get to damp areas on the gasket stye pipes should they be too close. Note roots are very powerful and have cause lots of costs fixing the damage they cause.

Quick google search found what looks like an interesting concept paper for underground piping & couple other places. FYI for chlorinated water you should look for pipe meets or exceeds "ASTM F2023" most PEX-A/B type PEX/XDLP if you go that direction.

http://plasticpipe.org/pdf/chapter07.pdf
Cross-linked polyethylene - Wikipedia, the free encyclopedia
Municipal Piping

Mark

 

[Qapla]

The tracer wire is a great idea. It does not have to be a large diameter wire but it does need to have a direct burial insulation on it. Checking with an irrigation supplier may be the easiest and cheapest way to find a suitable wire to use.

Keep in mind, I am in Florida and we do not have the freeze worries. That said, we installed irrigation along a roadway a while back. It was 3" mainline that went about 5 miles (that's about 26400 feet) and we used :thin wall" PVC. That has been about 8 years ago and no leaks yet. At home I have 1000 feet of 1 1/2" PVC that has been in the ground for 40_ years ... no leaks yet.