I don't work w/ pipe at all, but keep in mind an employer can add or ask for any additional test they want to make sure the person can perform the expected job. This sounds like that type of situation, maybe this is a typical connection that they do all the time, or maybe its a connection they do very rarely but they want to make sure that if they need it done, that the guy can do if needed.
Sounds like the company has its act together.
It always has amazed me how many outfits will give a test that does not closely (or sometimes even remotely) match production work, hire a guy, pay him to foul up several days or even weeks worth of production materials, run him off, only to go though the same ordeal with the next guy who shows up.
IMO there is nothing more important that an organization does than hiring. Yet for some outfits it seems to recieve a low priority.