oct ewj 24 online - Flipbook - Page 94
Combining Expert Witness Services
and Laboratory Analysis in Engineering
Failure Investigations
by Stephen Pitman, PhD CEng FIMMM, Principal Engineering Consultant, RINA Tech UK Ltd
In any complex plant or equipment failure investigation, where a root cause analysis is needed to show
cause or liability, the support of expert witnesses with
experience in different sectors and industries, backed
by access to advanced laboratories can be key to the
successful outcome of a case.
Failure investigations can require access to experts
from different disciplines combining their knowledge
to offer a complete support package to the client. This
is particularly important in cases that cross traditional
academic boundaries where one expert may not be
able to address all aspects of the failure. For example,
a mechanical failure may well require the combined
knowledge of mechanical engineers, stress modellers
and material scientists to interpret how a structure was
affected by its operating conditions/environment, the
operating stresses and how degradation of the structure may have reduced the available safety margins
causing the failure.
Figure 1: Typical ion chromatograph for anionic contamination on
electronic component
IC analysis for cations can also be used to detect
lithium contamination, due leakage from lithium ion
batteries, an element that can be difficult to detect by
other techniques or for the presence of ammonium
still a widespread cause of water leaks due to stress corrosion cracking of brass valve components (originally
known as season cracking seen in brass ammunition
cartridges stored in stables where high concentrations
of ammonium were present).
Engaging with a company that employs expert
witnesses from many sectors has the benefit of those
experts applying their knowledge from one sector to
solve problems in another. RINA’s heritage combines
expertise from marine, industrial, defence and manufacturing sectors. Techniques developed and applied in one sector are used to aid investigations in
others.
For example, ion chromatography (IC) is a technique
used to detect and quantify ionic contamination originating from the environment in which equipment
operates or from degradation of the materials used in
the equipment’s manufacture. A technique that was
historically used in the electronics industry, to monitor
process cleanliness, with the right knowledge and experience can now be applied to detect and monitor
degradation due to ionic contamination in a wide
range of applications including:
• Finding airborne contamination from neighbouring waste disposal facilities affecting the air intake
system at a data centre.
Figure 2: Ion chromatograph for cation contamination on printed
circuit board
There are many advantages in having direct access to
an in-house laboratory equipped with the analytical
toolkit considered essential for investigating engineering failures. These techniques may include:
• mechanical testing (Tensile/compression, hardness
and impact testing),
• (IC) Fourier transform infra-red spectroscopy
(FTIR) and gas chromatography-mass spectroscopy
(GCMS) to identify materials and organic contaminants, and
• Quantifying airborne contamination and their
effect on insulator surfaces of high voltage equipment
• Measuring contamination on gas turbine blade components to consider whether adequate air filtration
had been used.
• various microscopy techniques to examine fracture
surfaces or material structures at high magnification
(including optical and scanning electron microscopy
(SEM)).
• Detecting moisture ingress due to formation of
adipic acid through hydrolysis of nylon used in casing
of electronic equipment.
EXPERT WITNESS JOURNAL
92
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