The 12# mine steel arch is made of mine i beam, the material of the 12# mine steel arch is Q345B, the Application: It is mainly used in mine roadway, secondary support of mine roadway and supporting support for the tunnel. Specification: T chanel support, arch support Size: 12# Material: Q345B Characteristic: High pressure, long support time, easy to install, etc. 1. The outer edge of the i-steel shall not be more than 2.4% of the width of the legs. 2. The bending deflection of the i-steel shall not be greater than 1.0mm. 3. The degree of eccentricity of i-steel shall not be more than 2% of the width of the legs. Degree of eccentricity = b2-b1/2. 4. The bending degree of the steel shall not be greater than 3mm.