镀锌方管的镀锌分层以及弯曲强度：热镀锌方管合金层与纯锌层、钢管基体融为一体。故其耐腐蚀能力强。锌层是电镀层，锌层与钢管基体独立分层。锌层较薄，锌层简单附着在钢管基体上， 镀锌方管容易脱落。故其耐腐蚀性能差。镀锌方管在新建住宅中，禁止使用冷镀锌钢管作为给水管。

Galvanized layering and bending strength of galvanized square pipe: Hot-dipped galvanized square pipe alloy layer is integrated with pure zinc layer and steel pipe matrix. Therefore, it has strong corrosion resistance. Zinc layer is an electroplating layer, and zinc layer is separately stratified with the steel tube matrix. The zinc layer is thin, and the zinc layer is simply attached to the steel tube matrix. The galvanized square tube is easy to fall off. Therefore, its corrosion resistance is poor. Galvanized square pipes are prohibited to be used as water supply pipes in newly built residential buildings. 热镀锌方管弯曲试验公称口径不大于50mm的镀锌钢管应作冷弯曲试验。弯曲角度为90°，弯曲半径为外径的8倍。

The bending test of galvanized square pipe with nominal diameter less than 50 mm should be carried out by cold bending test. The bending angle is 90 degrees and the bending radius is 8 times of the outer diameter.