According to the shape, size, location and protection conditions of the cast steel parts, choose the appropriate transmission method. In the case of implementation should be given priority to single-wall transillumination, in the single-wall transillumination can not be implemented before allowing the use of double-wall transillumination method. In practice, single-wall external transmission method, internal transmission eccentric method, internal transmission centre method, double-wall transmission method is usually used for liquid air separation plant valve inspection.
When the internal diameter of the cast steel part is large, the internal penetration centre or internal penetration eccentric method is used.
When the bore diameter of the smaller cast steel parts using double-wall transillumination, and at least once in each of the two mutually perpendicular direction transillumination.
Cast steel parts variable cross-sectional transillumination technical measures
Double film technology
When the thickness of the workpiece varies greatly and two films with different sensitivities are used, the film with the higher sensitivity should be suitable for the transillumination of the thicker part of the workpiece and the film with the lower sensitivity should be suitable for the transillumination of the smaller part of the thickness of the workpiece. When the thickness of the workpiece does not vary considerably and two films of the same sensitivity are used, a single film should be used to evaluate the area of small thickness, and two films should be used to evaluate the area of large thickness when superimposed.
Appropriate increase in transmittance voltage technique
For liquid air separation plant valve cross-sectional thickness changes are relatively small, especially when the cross-sectional thickness is continuously changing, can be used to appropriately increase the transillumination voltage technology for transillumination, improve the thickness tolerance.
Compensation techniques
For liquid air separation plant valve cross-sectional thickness variations or shaped workpieces, compensation technology should be used for transillumination.
By using the above technical measures, Dear Air Separation can ensure the quality of the valve body radiographic inspection negatives, thus ensuring the small air separation units, large air separation units and liquid air separation plants detection rate of valve body casting defects.
