Page 211 - CW E-Magazine (26-9-2023)

Special Report

and the thermogram of the catalytic
converter is shown in the right and the
left side of the Figure-22, respectively.
The refi nery was subsequently shut
down for off-line inspection. Thoro-
ugh inspection revealed that the top
portion of the shell had bulged and
a small crack developed causing the
leakage. The root cause however was
falling of lining on the internal surface
of the shell(16, 17).

CONCLUSION
Leakages from industrial pressure
Fig. 17: Electromagnetic Spectrum showing wavelength range of IR radiation vessels can damage equipments and
lead to unexpected shutdown. Produc-
tion and manufacturing operations
can be affected by even small leak-
ages. Above all, occupational safety is
compromised if the leaked material is
poisonous or combustible. Leaks in in-
dustrial facilities are not something to
be taken lightly, as exposure to harm-
ful gases and liquids can cause severe
health effects. In case the pressure
vessels contain fl ammable/explosive
gases, the leakage can lead to severe
explosion and fi re hazards. Hence, it
is the responsibility of the engineers to
identify the risks associated with unex-
pected leakages and ensure that the leak
is found at an early stage.
Fig. 18: Principle of measuring radiant heat stress by Thermography
The accuracy of pressure decay test
depends on the size of the leak/part
and is more suitable for small vessels.
Vacuum decay test can assess leakage
rate, but is less sensitive to tempera-
ture variation. Hydrostatic testing is
very commonly used for off-line ins-
pection of leakage in a pressure ves-
sel and leakage fl ow rate can be mea-
sured. However, it requires use of an
incompressible fl uid such as water and
it suffers a drawback that if the pres-
sure vessel develops leak/defect, the
same can no longer be used further. In
the application of tracer gas/sniff test,
Helium (He) is most commonly used
and leak rate can be measured and ex-
Fig. 19: Basic Confi guration of IR Imager pressed as Helium standard leak rate

Chemical Weekly September 26, 2023 211

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