Metal roof, the basic material (aluminum, manganese, magnesium) alloy, grade 3004 (AI Mn Mg), due to the aluminum metal roof is 0.7 ~ 1.2mm thick, moderate structural strength, ease of welding bending, in addition to the standard connection addition to the technical, vents, entrances, etc., in the field of welding. At the same time in different pressure states, can ensure the integrity of the material, in line with GB3880-97 standard or ASTM3004 standard, it is widely used in the construction of the maintenance system.