This Standard specifies the selection and preparation of samples, hairline inspection method, representation and assessment of inspection results, and test report, etc. for the use of etching test method of tower samples for inspection of non-metallic inclusions of steel. This Standard is applicable to the inspection of the number, length, and distribution of hairlines in steel by etching test of tower samples of steel with a diameter, side length, or thickness of 16 mm ~ 150 mm. Other products or specifications may refer to.