Need an opinion regarding joint failure

[herbj]

I recently installed 2inch pvc glued in lieu of 2inch 160 psi 160 psi slip joint gasketed pipe. The pipe length is 350 feet and is routed in a sweeping curve of about 45 degrees. The pipe was installed in virgin soil that is essentially a sandloam/gravel soil. I have been advised that this installation is subject to failure. Would appreciate any comments.

 

[bimr]

One would assume that your adviser is concerned with the rigid joints since the 2" pipe has the flexibility to bend. This pipe is relatively inexpensive at around $20-30 per foot installed.

The preferred joint for underground work is the gasketed bell and spigot joint. This joint is preferred because the joint has some flexibility should there be ground movement.

However, the concern for pipe failure is probably more significant for larger diameter pipe. The depth of the pipe will have some bearing on the issue as well. Climate issues such as freeze thaw will also have some impact.

If your adviser can point to a similar installation where the pipe is breaking, then consider replacement. Otherwise, consider the risk of a pipe failure. If the consequence of a pipe failure is not a big concern, then let it go. If the pipe does break, you can install a flexible joint at the location where the pipe break occurs.

 

[btrueblood]

You might want to hand backfill several inches of cover over the pipe, to avoid having big rocks dropping directly on the PVC. Otherwise, I see very little risk. I've personally installed 10's of miles of similar sized solvent-welded PVC pipe as water well piping, we've rarely had trouble, and this in very heavy glacial till soils (big rocks). Bimr is correct too, we usually made the switch to gasketed joints for 4" and larger pipes (water mains), as it's a bit more forgiving (gluing up 4" pieces is a bit more of a chore also, pretty much a 2-man job).

 

[rconner]

fyi

http://eng-tips.com/viewthread.cfm?qid=227506

 

[btrueblood]

OP: You do plan to hydro your line before backfilling, right?

 

[herbj]

Yes, we did a 2-hr. hydro test at 100 psi and everything held fine. A majority of the pipe had at least 3-4 ft. of fill on it except for the major curb-stop taps, and everything is fine. The line has been in service for about 1 month and has sustained in excess of 200 trips with 20-yard side dumps as well as the passage of much heavy equipment. I think I'm okay?