I dont know much about door openers, but do know a lot about steel.
Typical generic black pipe is not made to withstand any sort of mechanical load. It could be virtually any crappy brittle steel. Also 1" pipe will not be 1" OD...it will be larger and probably an oddball size.
Go to a steel yard and buy a piece of 1" OD x .120 wall 1010 HREW tubing. It's common stuff and shouldnt cost more than about $1.50/ft. You may have to buy a $20 stick though.
