[en] The paragraphs of JIS Z 3105 revised in 1977 are explained, and the problems that were examined by the special committee before the JIS Z 3105 is put in force are reviewed. The JIS Z 3105 consists of a general rule, a method of radiography, a method of classification of the radiographs, and recording. The main problems which were examined are as follows: The radiation penetration testing method of a circumferencial welding portion of a tube was included in the old specifications JIS Z 3105 (1973), but it is excluded in the new specifications, because another specification JIS Z 3108 was established. The gradation meters of D1, D2, D3 and D4 types are added to the gradation meters of the existing A and B types. A restriction in accordance with both focusing dimension and thickness of the welded material is provided between a distance between the focal point and the penetrometer and a distance between the penetrometer and the film. Radiograph concentration of parts other than the penetrometer discrimination and defects of a testing part are specified in accordance with thickness of the base metal. Inclusion of copper and copper oxides are added to the blowholes, the inclusions, cracks, bad penetration and bad fusion as defects for classifying gradation. The gradation of the revised JIS is classified into four grades in lieu of the old three grades. (Iwakiri, K.)