Adding hinges to steel box tube that is going to be powder coated - advice
Why not pre-drill the holes, put the screw in with tape before powdercoat. Then after complete, remove the screw and hopefully it won't crack around the tape. Or, get a removable pin hinge and weld one side to the frame and cover the pin holes. Or, weld a nut inside and cover to powdercoat. Or, use an anchor system, predrill the holes slightly over size. and leave the bottom open so you can relace the hinge, if need be, in the future.