The lines in question are not regulated, other than where they leak : )
Low pressure lines or feeder lines are not looked at by the state or FedGov. That, however, is likely to change.
The biggest casulaties are local polititions (the Gov) and folks who buy gas made from the oil.
If you know any welders, tell them to get up here and get tested/certified - there are bucs to made....for a while anyway.
Actually a couple of years ago I ran into this very issue. You are correct. If they leak in "remote" locations then it is regulated. There was an actual tightening of this regulation a few years back, but I don't have this information at my fingertips (DOT OPS Pipeline Safety Regulations, Hazardous Liquids Part 195). Will look for pertinent sections and will post links to the OPS.
I'm in the nuclear industry
I've dealt with MIC in condenser tubing.
MIC can be readily detectable by eddy current testing (both bobbin coil and pancake probes)
What technique was used to look for pitting?
Were these pits located near welds?