IMAGE QUALITY INDICATOR (IQI) OR PENETRAMETER
SELECTION FOR INDUSTRIAL RADIOGRAPHY
HOLE-TYPE IQI
The logic of
selection of hole type IQI is same as that for wire type IQI.
Please go through the below link for the selection of hole type IQI.
Refer Table
T-276; of ASME BPVC Section V;
Based on the nominal single-wall material thickness that you want to
radiograph, select the hole type IQI.
Example:
Suppose we want to radiograph a 7 mm thickness plate using hole type IQI, in film side.
From the table
T-276 the required hole type designation is 12 (6.4 through 9.5 in the table
T-276 in film side)
And in that,
the required essential hole is 2T.
After radiography if the radiography film shows 2T hole then we can say that the radiography procedure is acceptable in terms of sensitivity.
Alternate IQI
If the
required IQI of hole type designation is not available the equivalent hole
type
IQI sensitivity is as per table T-283
For the above
example; if the hole type designation of 12 is not available, we can use hole
type designation of 17 which should show 1T hole or we can use hole type
designation 7 which should show 4T hole in the radiography film.
The below table shows the Hole-Type IQI designation, Thickness and Hole Diameters. This table is from ASME BPVC Section V.
Some interesting facts about Hole-Type IQI
It is
interesting to note that all the Designation Numbers directly relate to the
thickness of the Hole Type IQI except for three, numbers 7, 12 and 17.
See
Table T-233.1
Another
feature of the Designation Number is in reference to the specific hole such as
1T, 2T, or 4T.
The T is the thickness of
a given IQI Designation such Number 15 for example. So the 1 x T hole has a
diameter of 0.015”.
Thus the 2 x T hole = 0.030”, 4 x T = 0.060”.
However this
rule does not hold for the smaller IQI Numbers 5 and 7 which are both identical
to Number 10.
To say it another way,
Numbers 5, 7 and, 10 all have the same diameter of 1T, 2T and 4T holes. See
table T-233.1
Further Suggested Reading:
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