Alstom India Limited Durgapur, WB, 713206 Geometrical Unsharpness : Geometric unsharpness (U g ) is simply the amount of blurriness in a radiographic image due to the finite size of the radiation source or the geometrical configuration of the exposure setup. Calculation of Geometric Unsharpness The formula for calculation of Geometric Unsharpness is as follows Where F: source size: the maximum projected dimension of the radiating source (or effective focal spot) in the plane perpendicular to the distance D from the weld or object being radiographed. e.g. if two dimension of source size is 6 X 8 mm in two perpendicular direction then, F will be 10 mm (max dimension). d: distance from source side of weld or object being radiographed to the film. D: distance from source of radiation to weld or object being radiographed. Following is the image while measuring focal sizes of source of X-Ray. To find out the F for above formula the maximum direction as mentioned in ASME is to be measured which is diagonal of these two directions.
Geometrical Unsharpness : Geometric unsharpness (Ug) is simply
the amount of blurriness in a radiographic image due to the finite
size of the radiation source or the geometrical configuration of
the exposure setup. Calculation of Geometric UnsharpnessThe formula
for calculation of Geometric Unsharpness is as follows
Where F: source size: the maximum projected dimension of the
radiating source (or effective focal spot) in the plane
perpendicular to the distance D from the weld or object being
radiographed. e.g. if two dimension of source size is 6 X 8 mm in
two perpendicular direction then, F will be 10 mm (max dimension).
d: distance from source side of weld or object being radiographed
to the film.D: distance from source of radiation to weld or object
being radiographed.
Following is the image while measuring focal sizes of source of
X-Ray. To find out the F for above formula the maximum direction as
mentioned in ASME is to be measured which is diagonal of these two
directions.
In EN code too they provide 2 measurements in two above
mentioned directions. Hence to calculate F for Ug calculation, it
has to be maximum values from these two perpendicular
directions.
