Over 30 years ago, a major gas producer/transporter specified X42 for sour gas service. Because even then steel manufacturers were making steel on a "one size fits all" basis, they actually recieved X58 equivalent pipe and failed to meet hardness requirements in the HAZ of the long seam and the circ seam welds. They ended up doing a whole lot of heat treating. I advised them that they needed to purchase this steel to a specified chemistry further limiting carbon, manganese, silicon, vanadium/niobium as my company was doing in similar sour service applications. So beware and act accordingly!!