1.1 This specification covers three grades of zirconium and zirconium alloy seamless and welded tubes.1.2 Unless a single unit is used, for example corrosion mass gain in mg/dm2, the values stated in either inch-pound or SI units are This specification covers the three grades of zirconium and zirconium alloy seamless and welded tubes. The tubes are furnished in three grades as Grade R60702 which is an unalloyed zirconium, Grade R60704 which is zirconium-tin alloy, and Grade R60705