Let me cue you into a little known fact nowadays...
In america, nearly all steel production is derived from recycled scrap metal. You cannot get high grade cast iron anymore that is american origin...or wrought iron of high grade. These products require iron ore in large quantities and a process that is not friendly to the environmental gods of the hippy lefties.
Maybe this pipeline requires steel of such a grade that general run of the mill scrap is not sufficient for procurement...just a possibility that popped into my mind.