... for chemical industry, metallurgy, and electric industry.hydrogen≥99.9GB-T3634-1995bottle/cylinderChemical industry, glasses, ... cutting, heating, organic raw materialspropene≥99.5Q/DY-98KGWelding, cuttingpure hydrogen≥99.99GB/T7445-1995bottle/cylinder Raw ... 99.99 GB/T4842-95Bottle Welding shielded welding, stainless steel smelting, container, steel structure manufacture, mold processing, etc. 99.999 ...