FIELD OF INVENTION
The invention relates to an Ultrasonic test device having an UT means and a
probe. More particularly, the invention relates to a device for setting the
calibration sensitivity level of an ultrasonic testing means by adapting a probe.
BACKGROUND OF INVENTION
Ultrasonic testing is a well-established non-destructive testing method for
evaluating the quality of raw material, semi-finished and finished products.
One of the steps in the prior art testing method is : setting the amplifier gain for
testing by using a standard reference reflector made of material same as that of
the test piece or material with similar acoustic properties. The reflector is usually
one of the following : (1) flat bottom hole, (2) side drilled hole, (3) notch, (4)
back wall as a reflector. The reflector is of different sizes selected according to
the application standard.
These reflectors in the form of blocks are manufactured according to the
standards of ASME Sec V, BIS The standards require that the reference reflectors
be manufactured such as to have accurate dimensions in respect of diameter,
flatness, parallelism and perpendicularity with close tolerance since the reference
amplifier gain settings are very much affected by the above dimensions. Thus,
the manufacture of flat bottom hole reference reflectors involves drilling a hole

keeping the flat surface parallel to the top surface on completion of the drilling.
The flatness is to be ensured within a close tolerance which requires
considerable effort and precise measuring instruments.
Ultrasonic testing for detecting the defects is based on the principle of reflection
when a different material is encountered. During ultrasonic testing, the
ultrasound waves are injected into the material and whenever a different
material is encountered in its path, a refection takes place. The reflected sound
energy is dependent on the area of the reflector, its physical property and the
incident energy. For a particular material, the physical properties are constant,
and keeping the incident energy constant for particular testing, the area of the
reflector causing the reflection is quantified by measuring the reflected sound
energy which is proportional to the height of the echo displayed on the UT
equipment. Hence for qualification, this echo height is used in comparison with a
standard reflector surface namely a flat surface in a Flat bottom hole in a block
as per the international standards such as ASME E 127.
In the above mentioned block, the reflecting surface is made by drilling or
Electro discharge machining and since the reflecting surface is inside the block, it
is difficult to ensure the required flatness, parallelism to the test surface,
diameter and surface finish of the reflector. Additionally, if a specific surface
condition (such as surface overlay, dissimilar weld, special process welds such as
friction weld) is to be used as a reflecting surface, it would not be possible to do
so in the blocks as per above standard, It is also not possible to introduce a
defect or surface of a natural defect as a reflecting surface, In additions, a
specific metallurgical property cannot be introduced in the block as per the
standard.
To ensure that the surface of the reflector face is representative of the actual
discontinuity encountered during testing is not possible in the present
arrangement.
Hence there is a requirement for developing a single block which eliminates the
disadvantages of prior art.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose, a device for setting the
calibration sensitivity level of an ultrasonic testing means by adapting a probe.
Another object of the invention is to propose a device for setting the calibration
level of an ultrasonic testing means by adapting a probe, which comprises a
material same as that of the job.
Yet another object of the invention is to propose a device for setting the
calibration sensitivity level of an ultrasonic testing means by adapting a probe.,
which considers the effect of metallurgical and other related conditions likely to
affect the ultrasonic material properties in the representative reflector.
A still another object of the invention is to propose a device for setting the
calibration sensitivity level of an ultrasonic testing means by adapting a probe,
which ensures that the metallurgical conditions for example, the surface heat
treatment, surface overlay, dissimilar material welding, special welding processes
such as friction welding, flash butt welding, induction pressure welding found in
the actual job is reproduced in the reference reflector accurately.
A further object of the invention is to propose a device for setting the calibration
sensitivity level of an ultrasonic testing means by adapting a probe, which can be
manufactured with widely available machine tools so that they can be
manufactured accurately and with ease.
SUMMARY OF THE INVENTION
Accordingly, there is provided a device for setting the calibration sensitivity level
of an ultrasonic testing means by adapting a probe, comprising a single
cylindrical block with a cylindrical projection from one end, and concentric to the
front, the single cylindrical block being configurable with different heights (L) and
with different step diameters (d). The height (H) being fixed, the block having at
least three faces (A,B,C), a probe (P) disposable on the second face (B) on which
the ultrasound being injected through the ultrasonic testing means; a display
device displaying the sound wave (Y) when the sound traveling in a straight path
from the second face (B), and gets reflected by the third face (c); the display
device further displaying the second wave (z) when the reflected sound travels
from the third face (c) and gets reflected by the first face (A); and the ultrasonic
testing means is enabled to set a reference amplifier gain by adjusting an echo
height to 80% of the full screen height of the display by varying the amplifier
gain of the UTI-means. The echo height being the height of the indicated display
of the second wave (z), if is directly proportional to the area of the reflecting
surface caused by the reference reflector of the diameter (d).
At the outset of the description, which follows, it is to be understood that the
ensuring description only illustrates a particular form of this invention. However,
such a particular form is only an exemplary embodiment and the teaching of the
invention is not intended to be taken restrictively.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Shows an embodiment of a device according to prior art.
Figure 2 - Shows an embodiment of the device according to the invention.
Figure 3 - Illustrates an embodiment of the invention implementing the defect
detection.
Figure 4 - Illustrates another embodiment of the invention where the device is
configured with different surface overlay.
Figure 5 - Illustrates a third embodiment of the inventive device with a surface
of natural defect.
Figure 6 - Shows a further embodiment of the inventive device with embedded
defect.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE
INVENTION
The device comprises a single block (1) produced of a material identical to that
of the job material having a projection of known metal distances (L + H) The
block (1) illustrated here, is of round shape but it is possible to make blocks of
different shapes also. The projection can be manufactured us various ways for
example, a reflecting surface, which can be a) of required shape, b) size, c)
required surface finish, d) required material, e) required metallurgical conditions,
f) surface of the actual defect. Alternatively, the projection can have an actual
defect itself so that the testing will truly assess the defect size and nature. The
projection H is to be more than the wavelength of sound in the material.
The device material has the same heat treatment and other metallurgical and
acoustic properties as that of the job (not shown) under test.
The UT probe is initially set on the top surface (side A B) of the block (1). The
probe is moved forward and backward till the echo from the reference reflector
i.e. the projection is maximized. Then the gain control is adjusted to bring the
echo height to 80%. The amplifier gain setting is used as a reference setting for
further testing of the job. These and other objects and advantages of the
invention will be apparent from the ensuing description.
The face B of the device shown in figure 2 Can also be inclined at various angles
for angle beam examination such that the ultrasound beam is incident at a
direction perpendicular to the surface A of the projection in the device.
As shown in figure 3, a probe (P) is placed on the face B of the block and the
ultrasound is injected into it. The sound travels in a straight path and is reflected
first at the surface C and is displayed (Y) on the display screen. The sound
travels further and is reflected from the surface A and is displayed (Z) on the
display screen.
The height of the indicated display (Z) is directly proportional to the area of the
reflecting surface caused by the reference reflector of diameter 'd'. This echo
height is adjusted to 80% of the full screen height of the display by varying the
amplifier gain in the UT equipment. This sets the reference amplifier gain in the
equipment and the equipment is now set for testing. While testing, the height of
any signal in the display from a suspected defect is measured. The measured
height is proportional to the surface area of the reflecting defect and this height
is used for sizing of the defect.
To suit the block according to the job to be tested, the surface A is prepared with
a different heat treatment or overlay or surface of a natural defect which will
give a very accurate comparison for testing the actual job.
Figure 4, Figure 5, Figure 6, each illustrates the block with different reflecting
surfaces such as overlay, Surface of natural defect, and embedded natural
defect.
WE CLAIM
1. A device for setting the calibration sensitivity level of an ultrasonic testing
means by adapting a probe, comprising :-
- a single cylindrical block (1) with a cylindrical projection from one end,
and concentric to the front, the single cylindrical block (1) being
configurable with different heights (L) and with different step diameters
(d), the height (H) being fixed, the block (1) having at least three faces
(A,B,C),
- a probe (P) disposable on the second face (B) on which the ultrasound
being injected through the ultrasonic testing means;
- a display device displaying a first sound wave (Y) when the sound after
traveling in a straight path from the second face (B) gets reflected by the
third face (C);
- the display device further displaying a second wave (z) when the reflected
sound after traveling from the third face (c) gets reflected by the first face
(A); and
- the ultrasonic testing means is enabled to set a reference amplifier gain
by adjusting an echo height to 80% of the full screen height of the display
by varying the amplifier gain of the UTI-means, the echo height being the
height of the indicated display (z) which is directly proportional to the area
of the reflecting surface caused by the reference reflector of the diameter
(d).
2. The device as claimed in claim 1, wherein the height, step and diameter
of the cylindrical block (1) varies between 100 to 300 mm, and 2 to 5 mm
respectively.
3. The device as claimed in claim 1 or 2, wherein the height (L), step (H),
and diameter (d) of the block (1) is 100 mm, 6 mm, and 2 mm
respectively.
4. The device as claimed in claim 1, wherein the device is enabled to detect
embedded defect in the job, wherein the embedded defect can be gas
inclusion, slag inclusion, lack of fusion, crack, lamination, and wherein the
device is capable of detecting defects for the sizes ranging from 1 to 4
mm.
5. The device as claimed in claim 1, wherein the height of any signal in the
display during the testing from a suspected defect is measured which is
used for sizing of the defect.
6. The device as claimed in claim 1, wherein the first surface (Face A)
having different metallurgical property compared to the body, for
example, a different weld deposit or anisotropy property.
7. The device as claimed in claim 1 or 2, wherein the first surface (A) has
different surface heat treatment, surface overlay, dissimilar weld, special
process welds such as friction weld, flash butt weld, induction pressure
welds on the face A.
8. The device as claimed in claim 1, wherein the device is configurable with
widely available machine tools.
9. The device as claimed in any of the preceding claims, wherein the shape
of the device is such that the same is enabled to measure accurately the
defects to a close tolerance with respect to flatness, perpendicularity,
parallelism, roundness, area of reflector.