HDPE Connection Methods

[kzegel]

Hello All -

We are designing a water remediation system with 10,000 feet of 3/4" DR 11 HDPE. I've heard of stories of poor butt welds resulting in significant constriction in the pipe and headloss (rendering the pumps useless until the welds were fixed). I'm sure it was poor installation technique/QC of joints but which joint method do you believe results in the lowest likelihood of constriction/internal bead formation (or is there even a method that eliminates this)? I know there are various joint methods but I've only used butt welding on larger diameter pipes.

Best regards,
Ken

 

[zdas04]

Did 3/4" mean "three or four inch" or "0.75 inch"? If it is the latter, then there is no way you are going to successfully lay 2 miles of 3/4 inch SDR 11 pipe, the tolerances are just too small (ID is 0.61 and a tiny misalignment is too big a deal).

For integer sizes of pipe the answer is QA/QC. Specify the acceptable misalignment and have someone verify that every single joint is withing that tolerance. It is a lot less expensive than digging it up because of failed joints through poor fusion or major misalignment.

David

 

[kzegel]

Thanks. Unfortunately, it is the latter (0.75"). A little more clarification; there are six wells, each about 1,500 feet from the treatment building. I was hoping we could get 500 foot rolls and limit the number of joints. The other option I toyed with was scaling up the size to 1.25" or 1.5" to help limit the margin of installation error. If I do that I eliminate any scouring velocity in the pipe. But, maybe in this case that's the better design and we just plan/design for a long-term maintenance program to jet the lines if needed. Our water chemistry is tough; we're saturated with alkalnity and hardness so I expect sediment and scale based on similar sites in the area.

 

[zdas04]

Sounds tough, but the margin of error in pipe that small is vanishingly small. With 1.5 inch you probably have a good chance of success and the flow area is only 4 times larger. I'd plan on doing maintenance.

David

 

[ram0608]

If the pipe size is 0.75", you can get 1500 feet in a sigle roll, in fact upto 3300 feet also can give in a sigle roll. Ask your manufactuerer's to provide the total quantity in a single roll, if it is possible you may not have other problems.