by Karen Fox, CRL, Level 2 Electrical Thermographer, Level 1 Airborne Ultrasound, IRISS Inc.
Overview
Infrared thermography is a widely accepted preventive maintenance technology
both for land-based facilities as well as maritime applications. Furthermore, we know
that planning and carrying out regular equipment maintenance is better than no
maintenance at all. Electrical Equipment and electromechanical assets like
motors, especially on ships where both vibration and airborne contamination can
be problematic is often susceptible to sudden, unexpected failure. Maintenance and
repair is not an easy task on a vessel at sea, and every three to five years, cruise lines
send their ships into dry dock for both major aesthetic upgrades and renovations, as
well as for routine maintenance upgrades. In addition, the pressure of the NFPA 70E
requirements, as well as corporate safety initiatives, have propelled the maintenance
and reliability engineers to implement more restrictions on their condition-based
monitoring programs for energized equipment. Planned Maintenance System (PMS)
is now available on every ship, which includes, but is not limited to, infrared
thermography and ultrasound testing for bus bars, transformers, Power
Distribution Panels, pumps, switchboards, MCC, circuit breaker panels, bearings,
motors, steam traps and more.
Analysis of Current Inspection Program
A large cruise ship builder approached IRISS after completing their research and
determined that their fleet of ships should retrofit Infrared Windows as an alternative
method of conducting safer, standards-compliant inspections.
The reliability of the main systems and the subsystems, as well as critical
electrical equipment was identified, and the IRISS VPT-75 three-inch diameter
round windows were installed into dry transformer panel covers in the engine room.
It was determined that more frequent inspections of energized equipment could be
attained by retrofitting Infrared Windows for routine inspections of the equipment
which did not trigger elevated levels of PPE required per NFPA 70E, thus also
reducing inspection time and maintenance costs. The team decided to integrate
infrared thermography into the PMS as a first line of defense, and thermal imaging is
used to capture baseline images and trends on the electrical equipment.
With the Infrared Windows installed, there is no requirement to remove panels or
wear cumbersome arc flash rated suits, hoods and face shields. In
addition, inspections were now performed on electrical equipment that had
previously been considered “uninspectable” due to overly high arc flash incident
energy levels for which the personnel did not have appropriate PPE.
The above photo shows a dry step-down transformer with the VPT-75 installed.
The Process
In this case, the step-down transformer equipment was identified, and the correct
size and placement of the Infrared Window was determined. When the ship was
brought into scheduled dry-dock, the equipment was completely de-energized to
make sure it was safely isolated, locked out and tagged out. Once de-energized,
the electricians removed the covers, and the Infrared Windows were retrofitted.
Approval to re-energize and operate the equipment was obtained, and locks and
tags were removed. The electricians confirmed the equipment was operating at
normal load levels and allowed sufficient time for the equipment to become
thermally stable. Infrared thermography was then performed on the equipment, and
any issues were noted. Inspections are now scheduled on a semi-annual basis,
and spot checks are performed whenever there is any suspicion of a problem due
to other warning signs being picked up by the maintenance and operations staff.
Results
A huge ROI with savings in time and money was achieved with the
implementation of IRISS transparent patented polymer Infrared Windows. This
allows more frequent inspections, and additionally, NFPA70E safety compliance
was also achieved. Even though many of the practices are similar in the marine
industry to those of land-based thermography, there are different potential problems,
concerns and safety issues that most land-based thermographers would never
think of or encounter. Thermography for the marine industry is just as important and
vital to overall reliability as it is to our land-based clients.
