He doesn't understand boiler codes and that's dangerous. Get a licensed boilermaker to handle it.
Skipping that step is begging for a dangerous blowout.
Our crew was stuck on a job because we needed a specific pressure valve gasket. The shipping slip said it would arrive by 10 AM, but the driver got lost and didn't show until after 3 PM. When he finally got there, he handed over a box labeled for plumbing fixtures instead. We all just stared at it and then burst out laughing because what else could you do.
My uncle still has his old oxy-acetylene setup from the 80s, and he showed me how they did EVERY cut by hand. These days, most shops use CNC plasma tables that punch out shapes in minutes. The accuracy is INSANE compared to eyeballing it with a torch. Makes you appreciate both the old skills and the new speed.