1, the flaw detector should evaluate the film. First, put the four indicators well, mark the film neatly and correctly, and classify it as scrap according to the type.
2. Start the first film review. First, find four fusion lines. Small-caliber pipes are oval, and the roots are all inside the circle.
3. Pore image is the most obvious, with dark center and shallow edge, nonmetallic slag inclusion and messy edge.
Biting the edge into a line is also a point, which seems to be broken and often meets. This defect is best determined, and the position is on the fusion line.
5. Impermeability is a big defect. The typical image is linear, the gap is too small and the edge is thick, and the projection part is close to the middle.
6, concave only on the overhead welding surface, the gap is too big is the key, concave opaque to distinguish, concave opaque into an arc.
7. Oblique and flat, without fusion, which is difficult to be found by routine photography. Its position is regular, between the groove and the layer.
8. Both transverse cracks and longitudinal cracks are dangerous. Transverse cracks are mostly on the surface, while longitudinal cracks are widely distributed and slightly wider in the middle.
Extended data
According to GB 3323-87 "Radiography and Quality Classification of Welded Butt Joints of Steel" and JB4730-94 "Non-destructive Testing of Pressure Vessels", the quality standard of radiographic inspection is divided into two parts: photographic quality grade and weld quality grade.
According to the parameters such as the type of radiation source and its energy, film type, sensitizing mode, negative film blackness and the distance between radiation source and film, the photographic quality grades are divided into three levels: A, AB and B, and the quality grades increase in turn. That is, when the latter distinguishes defects of the same size than the former, the thickness of transmission is greater. The photographic quality of welding seam of boiler and pressure vessel is AB grade.
Baidu encyclopedia-radiographic inspection
HowNet-X-ray Inspection Standard for Welds of People's Republic of China (PRC) and the First Ministry of Machinery Industry