PE Liner Collapse Pressure

I'm not sure of a code, but if you look here and download the technical guidelines it gives a table for time against SDR in terms of bar.

I've also seen one for mount of deformation versus pressure.

Collapse of the liner can occur if there is gas which diffuses through the liner into any space between the liner and the pipe. Unless you can evacuate this or keep it below a low pressure you have the potential for collapse.

Given that the liners are normally quite high SDR, this pressure is quite low

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

I lined a steel pipe a couple of years ago and the HDPE system I chose had interconnected grooves on the OD and was flanged on the ends. At every max pull you cut the steel and installed a steel flange with a tapped hole, then thermo-welded a flange on the HDPE that has a seating surface to match the steel flange gasket surface. Connect a vent riser to the tapped hole to prevent any build up of gas between the plastic and steel. The stuff I ran had a collapse dP of about 1/2 bar, so the manufacturer was concerned that someone look at all the vent risers (1/4 inch tubing bent into a 180º return) at least quarterly. They had had problems with wasp nests in the ends of the tubing creating enough back pressure to collapse the liner.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

The thinnest practical wall thickness is chosen to minimize the raw material cost of the HDPE liner. The physical limitations of the HDPE extrusion process are often the determining factor in allowable wall thickness. The industry interactive HDPE liner generally has a Dimensional Ratio of 41.

Thank you all for the response.

I believe various polymeric liners (for many purposes) have been pulled up inside e.g. stronger metal piping for some decades now. While I cannot claim to be an expert in these sort of dual pipe matters that have some perceived advantages, I have read enough to know these can involve some quite complicated considerations. I am also aware that some folks with Shell Canada (with some years of experience up to that time) wrote a quite extensive technical article, "Liner enhances pipeline integrity" based on their experience that appeared in the June 2004 PipeLine and Gas Technology periodical. While this article made the point, "Ensuring integrity of the lined pipeline needs to start during construction of the lined pipe system, and continue throughout the operating life of the pipeline", I also noticed many specific aspects of design and QA/QC planning (e.g. of the plastic piping) prior to construction had apparently evolved to that time and were mentioned in this article. While most of the special piping provisions mentioned had to do with the plastic permeation phenomena, annulus pressure and various needs and means of venting to avoid liner inversion/buckling (all that may not have been obvious to many at least some early practicioners), many other complex issues, concerns and suggestions/provisions were covered. I have noticed since that time a few additional issues of possible interest, reportedly results of maybe even less obvious specific permeation phenomena have also occurred that can be read in the papers I've seen now online at and
. I hope this additional information is helpful.

All have a Merry Christmas and/or very Joyous Holiday Season!