Use of non-metallic pipe for ASME B31.8 coded pipeline

[141109]

If non-metallic pipe is used for a buried pipeline as opposed to carbon steel does the location class design factor apply. If i'm in a class 1 div II area with 0.72 design factor how could this apply to the non-metallic pipe design? might it just be a factor on rating i.e. pipe pressure rating could be 1.38 higher than your actual design pressure?

 

[LittleInch]

That's an interesting question.

It won't affect the location class as this is driven by the location but how do you apply the class factor?

I think you need to look at 842.2 and Appendix A.

My reading is that you don't apply further factors to the stated design pressure for the pipe as this already contains sufficient FoS / Design factor for location classes 1 & 2

Locations classes 3 & 4 seem to limit the design pressure to 7 bar, though PA-11 pipe seems to be exempt.

what sort of "non metallic" pipe are you looking at?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[141109]

Thanks for the reply Little Inch! much appreciated.

There's a wide variety of non metallics nowadays and one or more types might be suitable. It could be a bonded flexible type pipe with thermoplastic liner / GRE outer or fully GRE.

It may be a case of back checking the pipe design with the 842.1.2 formula. Its still largely PD / 2t but with temp de-rated material strength as ASTM
D2837.

 

[141109]

Having said that 842.1.2 formula is applicable for thermoplastic pipe and ASTM D2837 is not for GRE pipe. 842.2.3 indicates ASTM D2517.