Understanding NRT- Reading 1- 2 of 2- Radiogaphic Testing A
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
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Wire Penetrameters<br />
ASTM Standard E747 covers the radiographic examination <strong>of</strong> materials using<br />
wire penetrameters (IQIs) to control image quality. Wire IQIs consist <strong>of</strong> a set<br />
<strong>of</strong> six wires arranged in order <strong>of</strong> increasing diameter and encapsulated<br />
between two sheets <strong>of</strong> clear plastic. E747 specifies four wire IQIs sets, which<br />
control the wire diameters. The set letter (A, B, C or D) is shown in the lower<br />
right corner <strong>of</strong> the IQI. The number in the lower left corner indicates the<br />
material group. The same image quality levels and expressions (i.e. 2-2T)<br />
used for hole-type IQIs are typically also used for wire IQIs. The wire sizes<br />
that correspond to various hole-type quality levels can be found in a table in<br />
E747 or can be calculated using the following formula.<br />
Where:<br />
F = 0.79 (constant form factor for wire)<br />
D = wire diameter (mm or inch)<br />
L = 7.6 mm or 0.3 inch (effective length <strong>of</strong> wire)<br />
T = Hole-type IQI thickness (mm or inch)<br />
H = Hole-type IQI hole diameter (mm or inch)<br />
Charlie Chong/ Fion Zhang
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