Material specification!. Material specification!. Mariela25 (Industrial) (OP) 18 Jan 17 15:01 Hi! I have a doubt about the schedule of a carbon steel universal joint. the technical features says it's 3000 psi/ Schedule 40. How are this two things related?. I'll apreciate your help! RE: Material specification!. MikeHalloran (Mechanical) 18 Jan 17 19:24 Pressure rating and Schedule number apply to pipe. If the joint yokes were machined from pipe, I'd worry about using them, since there may be welded seams where you don't want them, and mechanical properties are not guaranteed to the same standards. More likely, somebody's database is screwed up, and you can't trust getting the correct specs on any item from that supplier. Mike Halloran Pembroke Pines, FL, USA RE: Material specification!. Mariela25 (Industrial) (OP) 30 Jan 17 17:01 Thanks for your help!.