FIELD OF THE INVENTION
The invention relates to a reference block that can be used for standardization of
equipment for ultrasonic testing of tube butt welds. In particuar, the invention
relates to a reference block in tube that has side drilied hole as a reference
reflector instead of a notch. More particular, the invention relates to a process
of manufacturing a reference block for phased array and conventional ultrasonic
inspection of tube butt welds.
BACKGROUND OF THE INVENTION
Uitrasonic testing is one of the non-destructive testing methods for evaluating
the quality of welded components. In ultrasonic testing, reference blocks are
used to standardize the equipment before testing the component. The
equipment parameters are tuned to obtain the required sensitive at desired
area of interest demanded by the product. The sensitivity of ultrasonic testing
depends on the type and size of reference reflector used in the reference block.
Notch is the commonly used reference reflector for ultrasonic testing of tubes.
Side drilled holes, which has better sensitivity than notch, is not used in
preparing reference blocks for tubes because of difficulty in making a side drilled
hole in tube. Having a curved profile, tubes are inspected only with a reference
block having notch as a reference reflector. Notch is not a perfect reflector
because the reflect may come from either bottom of notch or top of the
notch. Especially when phased array ultrasonic testing is to be conducted in
tube, multiple angles will be reflected by the notch causing difficulty in
standardization of equipment. Therefore side drilled holes are preferred for
calibration of phased array ultrasonic testing equipment. The new invention is a

reference block with side drilled hole which can be used for ultrasonic testing of
tube butt welds with improved sensitivity.
US3933026 patent claims ultrasonic calibration block which is manufactured
using EDM process, which will be costly whereas present invention is a block
manufactured by using conventional manufacturing process.
US7617715 patent describes ultrasonic reference block to simulate porosity in
manufactured component. The block uses side drilled holes but on a flat
component. Present invention contains side drilled hole along the curvature of
the tube.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a process of manufacturing a
reference block for phased array for conventional ultrasonic inspection of tube
butt welds which has a side drilled hole acting as a reference reflector.
Another object of the invention is to propose a process of manufacturing a
reference block for phased array for conventional ultrasonic inspection of tube
butt welds which exhibits improved sensitivity than a commonly used notch.
A still another object of the invention is to propose a process of manufacturing a
reference block for phased array for conventional ultrasonic inspection of tube
butt welds, which is made up of tube of same material and same surface
condition that of a surface to be inspected.

A further object of the invention is to propose a process of manufacturing a
reference block for phased array for conventional ultrasonic inspect of tube
butt welds, which is enabled to accurately detect porosity in welded tubes.
A still further object of the invention is to propose a process of manufacturing a
reference block for phased array for conventional ultrasonic inspection of tube
butt welds, which can detect the defects of cylindrical in nature.
These and other objects and advantages of the invention will be apparent from
the ensuring description.
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.
SUMMARY OF THE INVENTION
Standardization of ultrasonic testing equipment to inspect tube welds is done
using a notch as the reference reflector. The severity of reflection from the notch
may be different for various angles. Reflection of ultrasound is possible from top
of me notch and bottom of the notch. This causes difficulty in Time corrected
gain calibration for sectorial scanning phased array ultrasonic testing. Side dnlled
hole acts as a more suitable reflector for time corrected gain calibration. Making
a side drilled hole is very difficult and it requires advanced machining processes.
This invention is a reference block which is made from a tube section of same
material or similar material of what is to be inspected. The tube section is

pressed to flat p.ate in room temperate and a side drilled hole is made from
the side for required dimension. After making the side drilled hole, the flat plate
,s again pressed to form a tube section of its original dimension. The surface
condition is verified to match with the surface of Job. The grain size of the tube is
verified at various stages of manufacture to ensure that the pressing operation is
not changing the attenuation property of the material. The surface condition of
the finished reference block is ensured to match with the surface condition of the
products to be tested.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure la shows a perspective view of the tube section of material same as
material to be testing ultrasonically
Figure lb shows perspective view of plate formed by pressing the tube
section shown in Figure la.
Figure 2 Shows a perspective view of the reference block with side drilled
hole showing first embodiment of invention
Figure 3 Shows front side of the reference block with side drilled hole.
Figure 4 Shows a process flow chart for manufacturing reference block with
a curvilinear side drilled hole for inspection of butt welds in tube.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The steps involved in fabrication of the block is explained in Figure la, lb, 2 and
3 Figure la shows a tube section (1) which is made of same material which is to
be inspected. The tube section (1) is cut along the axis of the tube. The tube
section (1) is then pressed to form a plate which is shown as item 2 figure 1b.

Side drilled hole(Item 3 Figure 1c) is drilled in the flat plate (Item 2 in Figure 1c).
The drilled plate is pressed to form a tube section with diameter equal to that of
the original tube section (Item 4 Figure 1C). Figure 3 shows the cross section of
the reference block which shows the diameter equal to the original diameter of
the tube.

WE CLAIM :
1. A process of manufacturing a reference block for phased array and
conventional ultrasonic inspection of tube butt welds, the process
comprising the steps of :-
providing a tube section having identical material composition that of
tube/pipe butt welds to be inspected;
cutting the tube section along the axis;
pressing the tube section to form a plate;
forming side drill holes on the formed plate; and
rolling the drilled plate to form a tube section having diameter equal to
that of the original pipe section.
2. The process as claimed in claim 1, wherein the hole formed is a curvilinear
side drilled hole.
3. The process as claimed in claim 1, wherein a defect of cylindrical nature is
created in the tube to inspect tube butt welds with improved defect
detection capability.