Mechanical Technology

Mechanical Technology — November 2015

• Phase angle analysis

of motor voltage and current as an

alternative to accelerometers.

• Wireless hybrid three-axis sensors

for vibration; multi-

spectrum acoustics; and temperature.

Similar developments have been taking place in methods for

periodic on-line assessments. Some interesting examples are:

• Radio frequency detection and analysis

for electrical

discharge current (in bearings, seals, gearboxes, etc.);

partial discharge; and arcing.

• Acoustic stress wave analysis

for condition assessment of

wooden poles (integrity of pole and anchoring).

• Infra-red gas analysis

• Ultrasonic detection

for assessing valves; heat exchang-

ers; and steam traps.

The point being made here is that this is a rapidly developing

field and it is quite possible that many unexpected failures,

which would previously have been described as ‘acts of God’

can now be predicted with high levels of confidence – and

not necessarily at high cost, either.

The common thread amongst these is that the technologies

are intended to be used while the asset is in normal service

and without affecting production. This is becoming more and

more important to organisations everywhere, for three main

reasons: to avoid loss of production; in the interests of safety;

and to avoid incidents of repeated infant mortality.

For the purposes of condition monitoring as discussed

here, tests are excluded. In this context a test is understood

to be

a process whereby a stress is imposed on the object

under test and the response to the stress is observed or

measured

. The object may need varying degrees of disas-

sembly but is usually isolated for the test and certainly not

in service. On the other hand, an assessment is passive in

nature by detecting, measuring and analysing signals avail-

able from the object by various means while it is on-line and

in normal service.

This is not to say that tests are not important, just that

they are not an option available to the reliability engineer for

assessing the health of assets in service. Note that here also

technology is making great strides and must be evaluated

when considering shut down inspections.

I would like to finish 2015 with a word of caution.

There is a very real danger that the technophiles in our

ranks (and I admit to being one of them) will become overly

enamoured with the cleverness and intricacies of truly amaz-

ing new technology, cunningly conceived and executed to

solve some real world problems that we think we may have.

However, the risk is that we (or our organisations) do not suffer

from those particular problems. It’s just that we would like to

think they do, so we can have the challenge and enjoyment

of getting our teeth stuck into something new and exciting.

The problem is that unless there are tangible benefits to

the organisation, this will not lead to favourable recognition

and sustained management support, and rightfully so.

Therefore, keep in mind the fundamental rule of physi-

cal asset management, that is: have a clear understanding

of the goals of the organisation and keep every decision in

total alignment with those goals. With that satisfied, taking

advantage of the capabilities of new technology can be both

stimulating and rewarding indeed.

Think of it as unexplored territory to prospect for new

opportunities in 2016.

⎪

Proactive maintenance

⎪