Recently, there is an increasing ne

Recently, there is an increasing need for cost-effective
NDE techniques that can reduce the inspection and maintenance costs in the refinery and petrochemical industries.
As a result, AE techniques offer some potential advantages
for structural integrity assessments of industrial vessels.
Especially in the case of large-scaled vessels, where the
operating stresses have a tendency to activate defect growth,
the AE technique can effectively detect defect activity and
overstressed areas, in contrast to the static conventional
NDE techniques. In addition, it can inspect an entire vessel
at one time without internal access to the vessel, which
provides the potential for inspection cost saving. Nevertheless, there are still some potential problems to be
resolved in the long term. In some cases, emissions were
detected but could not be identified, or structural defects are
entirely missed. In other cases, even dangerous aws were
acoustically indicated as insignificant sources unless they
grew during applied stress conditions. In addition, a disadvantage is that AE detects non-genuine events such as
mechanical impacts or rubbings. In the long term, there
are some main issues that need to be improved for the
successful application of AE and the reliable detection of
structural defects. These will include the formulation of test
procedures, the adequate stressing method and level in
relation to factors such as equipment geometry, material
properties and process parameters, and the signal pattern
recognition analysis to characterize the nature of active
defects.