... and use, grades are classified into 3 grades: GMPM.-1G MHLM.-2, GMHYM-3 . 3. Use GMPM. 1 is for the manufacture of electric vacuum ... . GMHI. M, 2, GMHYM. 3 is for the manufacture of tubes, electric light Lead strut, side rods, core lines. 4. Specification and tolerance ... impurities% ≤ 0 005 ≤ 0 005 ≤ 0 005 GMHI. M. 1 2, GMHYM. 3 is a high temperature rare earth lanthanum, yttrium molybdenum, and ...