Sizing PVC pipe 5

[bvelazquez]

I believe this should be an easy one for you all. I am locating a PVC 4"-diameter pipe underneath a slab on grade in a loading dock area. The PVC pipe will be approximately 12 inches below the slab on grade which is approximately 6 inches thick for a total of 18 inches below the loading point. How do I determine what schedule of pipe I need in order to resist the bearing pressure from a forklift or other heavy vehicle that transmits through the concrete slab into the compacted fill and eventually over the pipe? By the time the load is transmitted to the top of the pipe, I've got about 800 psf of bearing pressure. Any sugggestions on determining schedule of pipe?

 

[imok2]

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[CRG]

I can’t answer your question specifically; however, if you take a look at API Recommended Practice 1102, “Steel Pipelines Crossing Railroads and Highways,” you may get some insight into the calculation method required for your problem.

At first glance, I don’t think you have a problem with the load you described. The short term uniform collapse pressure for 4” sch 40 PVC is around 100 psi. Take a look at

http://www.us.piping.georgefischer.com/external/us_handbook/03.pdf

for engineering data on PVC pipe.

 

[jte]

bvelazquez-

You can also try to get some help from Harrington Plastics at

http://www.hipco.com.

jt

 

[bvi]

The concrete slab distributes the forklift load. Also, if you have properly compacted fill, it bridges the pipe, taking a large proportion of the load. The load is distributed based on relative stiffness of pipe and soil. Since PVC is flexible, properly compacted soil will likely take much of the load. Is is unlikely that any special consideration of forklift load is required. However, there are standard textbook calculations that can be performed to determine the load carried by the pipe. Note that it is not the wheel load directly above it, it will be something substantially less.

 

[TedLinsle]

This might help.

PWPIpe Technical Bulletin TB-D5
"Depth of Burial For PVC Pipe"

http://www.pwpipe.com/documents/pwpipe0013.pdf

On a quick and unrepeated calc, it looks like you'll have a 0.89% (on ASTM 2729 Drain Line) deflection on the pipe (verify), which is well within the 5% recommendation.

 

[PUMPDESIGNER]

tlindsley,
Nice paper, thank you for the link.

PUMPDESIGNER

 

[bvelazquez]

Thank you all for your help.

 

[PUMPDESIGNER]

jte and CRG,

This thread was a gold mine for good technical articles on PVC pipe. Your links were excellent also.

Thank you.

PUMPDESIGNER