Seamless, capillary, thin walled palladium alloy pipe mfr. - by drawing in stages to critical size with intermediate anneal

Seamless capillary thin-walled vacuum-tight pipes are mfd. from Pd-based alloys by drawing and reducing a pipe billet by stages so that each time the cross sectional area of the billet walls decreases by 60-80%. Each drawing stage is followed by an anneal at 830 plus-or-minus 30 degrees C. After decreasing the thickness of the pipe walls to 0.24-0.30 mm the billet is agains drawn and reduced by stages, each time decreasing the cross section area of the walls by 28-50% and then annealing at 750 + 20 degrees C after each drawing stage. The pipes are employed as diffusion membranes, selectively permeable to hydrogen (isotopes) and serve as the working elements of diffusion filters for superfine purification of hydrogen isotopes. The pipes will withstand a vacuum of 10-3-10-4 mm Hg and remain vacuum-tight after 1000 hrs. of operation in hydrogen-contg. media.