FIELD OF INVENTION:
The present invention generally relates to an apparatus in radiography testing of boiler pressure parts and structural butt welds or more particularly the subject matter of the invention relates to a method of improvement in geometric unsharpness by reducing the effective size of radioactive source in radiography testing method of butt welded joints.
BACKGROUND OF THE INVENTION:
In the field of Radiography Testing several types of techniques for the identification of defects in materials and welded joints are known in the art. Radiography Testing generate radiograph with useful data about defect (i.e. type of defect, size). Quality of radiograph depends on many factors (i.e. exposure technique, geometric unsharpness, film density, radiographic contrast, etc.). Many times a configuration (high thickness and lower diameter) of a pipe and header butt joint does not satisfy the required geometric unsharpness for panoramic shot radiographic technique, which leads to poor quality radiograph. To meet the requirement of geometric unsharpness in such cases SWSI (Single wall Single Image with offset) or DWSI (Double Wall Single Image) radiographic technique is used, which leads to increase in exposer time of RT and overall product cycle time. Increase in RT exposure time also leads to more radiation hazard for radiation worker.
While performing RT on one of the butt weld (i.e. 323x65mm), where configuration of joint did not satisfy geometric unsharpness (µg) requirement in panoramic shot RT technique for Ir192 source with 3.2mm source size.
But, there is still exists a problem regarding the thickness, as the IR192 source with high thickness cannot be used, which leads to not only increased SFD and increased overall production cycle time but also radiation hazard for radiation worker.

Hence, due to these disadvantages in the prior arts, there is always a need to develop a method for reducing effective size of the light source so that μg can be improved for given configuration of welded joint.
The present invention meets the above-mentioned need.
OBJECTS OF THE INVENTION:
It is therefore an object of the present invention to propose an apparatus for improvement in geometric unsharpness in radiography testing by reducing effective source size of radioactive element.
Another object of the invention is to propose an apparatus for improved quality of radiograph of welded joints for accurately confirming defects, which ensures safety and fitness of welded structures and installations.
A further object of the invention is to propose a methodology for improved radiography testing method of welded joints with panoramic shot or less SFD, which eliminates avoidable RT exposer time of welded joints and reduce the radiation hazard for radiation worker.
SUMMARY OF THE INVENTION:
An apparatus for improving geometric unsharpness (μg) in radiography testing of butt welds in boilers, comprises: a radioactive source with cylindrical shape; a disc or plate acts as an obstruction to radioactive source which further comprises a hole of a small diameter, though which the radiation can pass through.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a schematic diagram illustrating the principle of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment

disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
These and other advantages of the present subject matter would be described in greater detail with reference to the following figure. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
The subject matter disclosed herein relates to a method of improving the geometric unsharpness (μg), wherein the effective size of radioactive source has been reduced by obstructing the radiation of the radioactive source and allowing the radiation to pass from a smaller size hole as illustrated in Figure 1.
According to an implementation of the present subject matter, an apparatus is provided which comprises a cylindrical radioactive source

(1) of 3mm diameter and 2.7 mm length and an obstruction (2) two half valve layer thick MS (Mild Steel) plate having a hole (3) of 1.5 diameter.
Figure 1 illustrates the radioactive source (1) which has cylindrical shape and having diameter of 3mm and length of 2.7m, in accordance with an embodiment of the present subject matter. In the said embodiment, an disc or plate acts as obstruction (2) is provided which has thickness equal to two half valve layer thickness of the radioactive source (1); which comprises a hole (3) of small diameter such as 1.5mm to satisfy the substantial geometric unsharpness (μg). Hence, the radiation has been obstructed through the said plate or disc (2) and allowed to pass through the said hole (3) and thereby reducing the radioactive intensity.
A weld (5) is exposed with the radiation portion though the hole (3).
The radiation intensity is more for radiation passing through the hole (3) compound to the radiation passing through disc.
Though, the size of radioactive source is bigger, but the radiation pass through a small diametered hole (3) and thus making the radiation substantially effective when reaches to the radiograph (4) and hence an improved geometric unsharpness can be achieved.
The radioactivity tests have been performed for different SFD with and without obstruction.
From the results, it can be proved that μg achieved with the apparatus and method as claimed herein after shows improvement by reduction of size of effective source.
By this present invention, the quality of radiograph is improved in given constrained configuration, and also can save the time and reduce the radiation hazard for radiation worker.
Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to

the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system or device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

WE CLAIM:
1. An apparatus for improving geometric unsharpness (μg) in
radiography testing of butt welds in boilers, comprises:
- radioactive source (1) with cylindrical shape;
- a disc or plate (2) acts as an obstruction to radioactive source which further comprises a hole (3) of a small diameter, through which the radiation can pass on.

2. The apparatus for improving geometric unsharpness (μg) as claimed in claim 1, wherein said radioactive source (1) has diameter of 3mm and length of 2.7mm.
3. The apparatus for improving geometric unsharpness (μg) as claimed in claim 1, wherein said plate or disc has thickness of two half valve layer thickness of the said radioactive source (1) i.e, 2.5 mm.
4. The apparatus for improving geometric unsharpness (μg) as claimed in claim 1, wherein the said hole (3) has diameter of 1.5mm.
5. A method for improving geometric unsharpness (μg) in radiography testing of butt welds in boilers as claimed in claim 1, comprises
- selecting a suitable obstructer shape (i.e. disc, plate) with two half
value layer thickness of radioactive source (1);
- selecting a hole (3) diameter in obstructer (2) to meet the
requirement of geometric unsharpness;
- exposing radiograph by keeping source and obstructer hole (3) in
line.
6. The method for improving geometric unsharpness (μg) as claimed in
claim 5, wherein said radioactive source (1) has diameter of 3mm and
length of 2.7mm.

7. The method for improving geometric unsharpness (μg) as claimed in claim 5, has thickness of two half valve layer thickness of the said radioactive source (1) i.e, 2.5 mm.
8. The method for improving geometric unsharpness (μg) as claimed in claim 5, wherein the said hole (3) has diameter of 1.5mm.