方管是方形管材的一种称呼，也就是边长相等的的钢管。304方管是带钢经过工艺处理卷制而成。304方管的表面覆盖着各种保护层，将304方管和腐蚀性介质隔开，无缝方矩管就是防止304方管腐蚀有用的方法。

Square pipe is a name for square pipe, that is, steel pipe with equal side length. 304 square tube is rolled from strip steel after process treatment. The surface of 304 square tube is covered with various protective layers to separate 304 square tube from corrosive medium. Seamless square tube is a useful method to prevent 304 square tube from corrosion.

就目前来说，方管-镀锌方管-热镀锌方管-镀锌方管厂-镀锌方矩管厂家-天津镀锌方管厂埋在地下的燃气管道常用的外防腐涂层主要分为五类，有三层PE复合结构，环氧树脂粉末，无缝方矩管采用的都是镁合金对304方管进行保护的，无缝方矩管环氧煤沥青和PE胶带。

At present, the commonly used external anti-corrosion coatings for buried gas pipelines of square pipe - galvanized square pipe - hot-dip galvanized square pipe - galvanized square pipe factory - galvanized square pipe manufacturer - Tianjin galvanized square pipe factory are mainly divided into five categories, including three-layer PE composite structure, epoxy resin powder, seamless square pipe, which adopts magnesium alloy to protect 304 square pipe, seamless square pipe, epoxy coal tar pitch and PE tape.

因为三层PE复合结构，环氧树脂粉末防腐涂层性能优异，所以也是欧美国家埋地管道中的主要防腐涂层，我国人们使用都是根据耐用年限，维护费等全 面的经济因素考虑的，所以将三层PE复合结构防腐涂层作为选择，一般在牺牲阴极保护法中。

Because of the excellent performance of three-layer PE composite structure and epoxy resin powder anti-corrosion coating, it is also the main anti-corrosion coating in buried pipelines in Europe and America. Chinese people use it according to comprehensive economic factors such as service life and maintenance cost. Therefore, three-layer PE composite structure anti-corrosion coating is generally used in sacrificial cathodic protection method.

采用的都是镁合金对304方管进行保护的，304方管因为会在输出的电流过程中遭受到破坏，所以，所选用的镁合金牺牲阳极的设计使用年限是和管道的使用年限相匹配，这样既不会产生浪费，也不会增加维护的费用。

Magnesium alloy is used to protect the 304 square tube. Because the 304 square tube will be damaged in the process of output current, the design service life of the selected magnesium alloy sacrificial anode is matched with the service life of the pipeline, so there will be neither waste nor increase the maintenance cost.