Page 209 - CW E-Magazine (26-9-2023)

Special Report

vessel leakage detection is expected to
be achievable more reliably(12, 13).

Different applications of AE testing
of pressure vessels for leakage/crack
detection in continuous chemical pro-
cess industries are shown in Figures-14
&15. Figure-16 describes pictorially
how the AE transducers are placed
and distributed on the surface of a
hemispherical pressure vessel for con-
ducting the test. Typical results repre-
sentation of the test with defect loca-
tion is shown on the right side of the
figure. (12).

Infrared thermography
Infrared Thermography is a non-
destructive, intrusive, non-contact
mapping of thermal patterns on the
surface of the objects. It is usually used
to diagnose thermal behaviour and,
thereby, to assess the performance of
plant and machinery of a continuously
running process plant. This technique
is also called as Infrared (IR) Thermal
Imaging and may also be used to de-
termine the integrity of materials, and
processes including any leakage in a
pressure vessel. The instruments used
for thermography are available in
numerous configurations with varying
degree of complexity. The thermal maps
produced by infrared thermal imaging
instruments are called ‘Thermograms’.
To understand and interpret thermo-
grams, the thermographer must be fami-
liar with fundamentals of temperature
and heat transfer, infrared radiative
heat flow and performance of infrared
thermal imaging instruments(14, 15).

Radiative heat transfer takes place
in the IR portion of the spectrum, from
0.75-µm to about 100-µm. Figure-17
depictselectromagnetic spectrum show-
ing wavelength range of IR radiation.
Depending on the temperature of the
surface of most of the process indus-
try equipment/pressure vessels, it can
Fig. 14: AE Inspection of Pressure Vessels be observed that 1-µm to 20-µm wave

Chemical Weekly September 26, 2023 209

Contents Index to Advertisers Index to Products Advertised