根据不锈钢管的才子、外径及壁厚计算其每米理论重量，理论外表面积，理论内表面积的小工具。主要供非专业土木建筑人士使用。(A small tool for calculating the theoretical weight per meter, theoretical surface area, and theoretical surface area according to the talent, diameter and wall thickness of the stainless steel tube. It is mainly used by non professional civil engineers.)