FIELD OF INVENTION
The invention generally relates to a device to find the sensitivity at different
depths for a particular method of taking a radiograph. More particularly, the
invention relates to a device for determining whether a Radiography Technique
(RT) is capable of achieving the desired sensitivity.
BACKGROUND OF THE INVENTION
Radiography testing detects internal and surface defects in a component. The
sensitivity of the testing technique is judged / qualified by placing a device called
Image quality indicator (IQI) (for example, as per ASTM E747) on the
component and radiographically exposing the component along with the IQI. The
sensitivity is judged by checking whether an image of a particular specified wire
in the IQI is visible in the radiograph. The sensitivity is dependent on several
factors, namely, distance between the radiation source and the film, radiation
source and job top surface, thickness of the job, distance between the job top
surface and the film, size of the source, thickness of IQI, Diameter of wires in
the IQI. Generally, the parameters are chosen based on its ability to achieve the
required sensitivity such as 2% of job thickness.
In some components, the parameter for example, the distance between the
radiation source and the nearer surface is low due to the job design. In such a
case, the minimum required sensitivity may not be achieved based on the above
criteria of visibility of the wire. However, the sensitivity may be achieved for a
portion of the component in the thickness direction.

As per standard ASTM 747 of American Standard for Testing of materials, a wire
type image quality indicator is widely used for recording the sensitivity of
radiography process. However, it is employed in such a manner that the
sensitivity is identified only for the full thickness of the job, for example, when it
is placed on the surface nearest to the radiation source. Nevertheless, in this
application the device identifies the sensitivity at different portions in the through
thickness direction on the job.
Patent RO 119569 (Bl) discloses a method for obtaining an image quality, used
as main element for estimating the relative sensitivity of a radiographic image.
The device comprises a block with holes drilled at different location and at
different orientations. The method of the invention utilizes a standard Image
quality indicator, and different blocks are employed along with the standard IQIs.
French Patent 2625560 (Al) describes an image quality indicator where slots are
made at two places mutually perpendicular to each other which simulate the
cracks. This invention utilizes a different design of the block including a standard
wire type Image quality indicator.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a device for determining
whether a Radiography Technique (RT) is capable of achieving the desired
sensitivity.

Another object of the invention is to propose a device for determining whether a
Radiography Technique (RT) is capable of achieving the desired sensitivity, which
can identify the achievement or otherwise of the sensitivity for the entire
thickness or for partial portion of the thickness.
A further object of the invention is to propose a device for determining whether
a Radiography Technique (RT) is capable of achieving the desired sensitivity,
which can identify the portion of the component in the thickness direction where
the sensitivity requirements are not met.
A still further object of the invention is to propose a device for determining
whether a Radiography Technique (RT) is capable of achieving the desired
sensitivity, which can be used for a wide range of the thickness of the job which
is to be radiographed.
SUMMARY OF THE INVENTION
Accordingly, there is provided a device for determining whether a Radiography
Technique (RT) is capable of achieving the desired sensitivity, through the entire
thickness of a job. The device in case determines that the employed RT is not
capable to meet the sensitivity requirement throughout the entire thickness of
the job, it can identify at least the portion of the thickness which meets the
sensitivity requirements. The device is enabled to further identify the portion of
the component in the thickness direction where the sensitivity requirements are
not met. The entire process of sensitivity identification can be done by taking a

trial radiograph with the proposed device using the planned Radiography
technique for the job. The radiograph is processed and is evaluated as described
hereinabove.
The radiograph shows an image of the wires and wherever the wire is visible, it
is considered that the sensitivity at that portion of the thickness is acceptable.
Such a process establishes that by employing a particular technique, the
sensitivity requirement will be met or not. If the technique does not meet the
requirement, an alternative RT technique or NDT method has to be adapted.
Thus, a device is provided wherein the sensitivity is evaluated at different portion
in the thickness direction of a job in a planned technique of Radiography.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure -1 - Shows first embodiment of the device according to the invention.
Figure - 2 - Shows the lower member of the device of Figure - 1.
Figure - 3 - Shows the upper member of the device of Figure - 1.
Figure - 4 - Shows a set of wire visible in an image quality indicator (IQI)
according to the invention.
Figure - 5 - Shows a second embodiment of the invented device for higher
thickness jobs.

DETAIL DESCRIPTION OF THE INVENTION
As shown in figure 1, the device comprises :
- a lower member (1) formed of material identical to that of the job or a
material having radiation absorption capability similar to that of the job;
- an upper member (2) formed of a material identical to that of the job or a
material having radiation absorption capability similar to that of the job,
and
- a group of wire sets (3) visible in an image quality indicator (IQI).
The thickness of the members (1, 2) are the same. The lower member (1) has
an angle of 45 degree at the wedge. The material is same as that of the job or a
material which has a similar radiation absorption capability. The thickness (t) of
the lower member (1) should be equal to the thickness of the job or slightly
more than that of the job.
The upper member (2) is a plate with one side having an inclination of 45 degree
wedge in the thickness direction. The material is same as that of the job or a
material which has a similar radiation absorption capability. The thickness (t) of
the block (2) should be equal to the thickness of the job or slightly more than
that of the job.

The IQI set (3) is a group of a four sets of standard wire type Image Quality
Indicator (IQI) placed close to each other and kept inclined. For illustration
purpose, the standard IQI as per ASTM standard is shown. This assembly of IQI
sets are placed over the inclined surface of the wedge as shown in Fig. 1. The
length of the IQI set has to be chosen such that the penetrameter will extend
the full inclined length from top to bottom of the block. Alternatively, three sets
of Standard IQI as per DIN Standard or four sets as per ISO standard can also
be employed. The sets of IQIs can be fastened together by an adhesive tape or
any convenient means.
When it is required to radiograph more than thickness (t) then, two or more
members of the above assembly can be stacked one over the other such that the
location of the set of IQIs are aligned properly as shown in Fig. 5.

WE CLAIM
1. A device for determining whether a Radiography Technique (RT) is
capable of achieving the desired sensitivity, comprising :
- a lower member (1) formed of a material identical to that of the job
machined with an angle of at least 45 degree at the wedge;
- an upper member (2) formed of a material identical to that of the job
machined with one side having an inclination of 45° wedge in the
thickness direction; and
- a set of standard wire Image Quality indicators placed in between the two
wedges with the length of the set being selected to enable a
penetrameter extending the full inclined length of the members.
2. The device as claimed in claim 1, wherein two identical devices are
stacked one over the other, and employed for detecting the sensitivity for
higher thickness jobs.
3. A device for determining whether a Radiography Technique (RT) is
capable of achieving the desired sensitivity as substantially described and
illustrated herein with reference to the accompanying drawings.

The invention relates to a device for determining whether a Radiography
Technique (RT) is capable of achieving the desired sensitivity, comprising a lower
member (1) formed of a material identical to that of the job machined with an
angle of at least 45 degree at the wedge; an upper member (2) formed of a
material identical to that of the job machined with one side having an inclination
of 45° wedge in the thickness direction; and a set of standard wire Image Quality
indicators placed in between the two wedges with the length of the set being
selected to enable a penetrameter extending the full inclined length of the
members.