In Canada, it is typically the railway that has the last say. Check out http://www.tc.gc.ca/eng/railsafety/standards-tce10-236.htm for starters.
Too long didn't read? - 10 ft minimum for uncased crossings
If the site is being drilled already, you are already too late to contain spills from the highest risk operation. Drilling mud used for salt caverns are either brine or invert based. As cavern development moves into the mining stage, the risk of a spill is reduced significantly. There is...
To do 100% NDE on the long seam would be a bit impractical. We have 85 km stockpiled at the coating mill and 15 km is already coated. The coating mill is in a different city from the pipe mill. The pipe mill does 100% NDE on the long seam in the plant and we had third party mill inspectors...
I have some potentially defective 10" pipe that I need to use and need to develop the hydrotest criteria for. I say it is potentially defective because some 12" pipe that we bought from the same mill had some long seam defects that were discovered while hydrotesting. The mill has given us...
I have never considered casing for corrosion protection, but like BigInch mentioned, would use a TapeCoat or similar product. If it is any distance you are below ground, consider having your piping factory coated. For frost protection below ground (consideration where I live), we have had some...