An uncle of mine lived in the area of Grand Forks and spent much of his career outside working as a lineman in ND and Northern MN for Northern States Power. While I also have some experience kind of up close and personal off and on over many years with the cold and other conditions in this particular area, I believe with the even wilder and woolier conditions of many decades ago he was a tougher man than I will ever be (though I guess I thus do have some appreciation for your conditions.)
I suspect however long before the disaster nearly a hundred years ago with the Titanic and less popularized eventual events also with Liberty Ships, I think many or most folks basically realized that a whole lot of things get some brittle with cold! I guess about the only thing I would add is planned or unplanned release of pressurized gas through leaks or whatever other breeches from vessels or pipelines, and "decompressive cooling" or "decompression" thereby, can reportedly result in localized spots on pipelines or other containers of even more intense cold (that is some lower than whatever the ambient is). Per some authorities there has been historical concern or knowledge that under certain circumstances this can result in enhanced embrittlement,and more dramatic effects than just small leakage even in pipelines. While at least some former grades of otherwise rather formidable steel are known some subject to effects from the cold, I believe that on weaker plastics and elastomers etc. it can be expected to be even more dramatic.
You have been given some helpful references. I suspect virtually all of us were exposed in some extent to the various "gas laws" (in introductory physics classes etc.), and many more of us even in more specialized at least small pipe and tubing applications as we watch or feel what goes on under our car hoods or our home heat exchanging systems. While the good reference the Big one provided above did at least mention, "However, the general guidance in such case should be to look at the product properties, risk analysis, PRODUCT LEAKAGE" , and will a reduction in pressure at a certain point reduce the temperature to what is considered a low-temperature range." - I supplied the caps) there is apparently not a whole lot of detailed guidance out there concerning such phenomena in larger pipelines. While one reason for this is likely good or better performance in this regard of modern steel pipes, another reason is the detailed analysis of such effects is no doubt quite complicated, involving a rather hairy juxtaposition of hydraulic engineering, thermodynamics, and mechanics of materials that in whole is perhaps straining the ken of most common folk.
