PVC Pipe Pressure Capacity 1

[nornrich]

All,

I am looking for a reference to determine the air pressure capacity for standard PVC pipe. Any direction would be helpful.

Regards,

Rich...

Richard Nornhold, PE
nornrich@redrose.net

 

[smckennz]

Hi Rich
The pressure rating depends on the wall thickness, diameter and compliance standard. Your local PVC pipe manufacturer will help. I assume you are talking about uPVC
However PVC is not recommended (and often not permitted) for compressed air service; it shatters dangerously if it bursts. OK for a low pressure soap bubble leak test but thats it. ABS is often used for compressed air.

Cheers

Steve

 

[PUMPDESIGNER]

Manufacturer's of PVC fittings and pipe will often not even talk to you if you are doing compressible fluids. If you really need plastic try heavy wall HDPE, cannot shatter but might rip or tear. Also adds a lot of energy storage to any system. Fusion weld the system and you have no joints to fail. Fusion welding can be done with machine or electrically activated fittings by computer controlled machine that rents for a few hundred bucks.

PUMPDESIGNER

 

[Cockroach]

Use the triaxial state of stress equation, Von Mises-Hencky. In particular:

Sa = sqrt(3) P (R / [R^2 - 1]) for R = D/d

S = stress (allowable)
P = internal (bore) pressure
D = outer diameter of pipe
d = inner diameter or bore of the pipe

You can easily find the properties of the PVC plastic pipe, try DuPont, et al, and set the factor of safety, FS to:

FS = Sy / Sa for Sy = yield stress (2% offset).

The hoop stress predominates the wall element, radial stress simply being the reaction to internal pressure P. The longitudinal stress is only the normal reaction of pressure against the cross sectional area of the blocked end caps. (easy enough) You can now rearrange the equation and solve for "P", FS=1 if you're trying to Al Quada yourself.

The derivation method to Von Mises-Hencky can be found in most textbooks dealing with advanced mechanics of materials and follows from Thick Wall Pressure Vessel considerations.

I recommend hydrotesting the vessel, NOT air pressure for reasons previously mentioned. This is obvious, but it is needed to be restated here for purposes of clarity.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[bvi]

Best to get the pressure rating from the manufacturer. Do not use PVC for compressed air or other gas service as it would be hazardous. For liquid services, as an alternative you can use the wall thickness design equation in ASME B31.3, and the allowable stresses in that Code in Appendix B.