POWER April 2014 - 23

For example, care must be exercised in applying assumptions
for calculating wastage rates. FAC inspection data taken in 2007
at the previously mentioned Midwestern plant were the first such
data obtained since a particular unit went into service in 1972.
The wastage rate was calculated assuming 35 years of service,
and extrapolation showed it had sufficient remaining life to make
it to the 2010 planned outage. It was only after a second failure
was experienced with a component that staff realized new control
valves had been installed in 1998. The original gate valves
had been replaced with trim stacked drag valves, which were subsequently
deemed to have adversely affected flow patterns in the
pipe. This oversight could have been avoided by having accurate
3D intelligent models of the actual plant equipment.
Reducers and expanders account for most of the replaced components.
There are several different configurations of reducers, however,
which make data interpretation and damage prediction difficult.
The transition zone can be a straight taper, curved taper, stepped
taper, or a bulged taper, and the exact point of the thickness transition
varies. It is imperative that costly repair/replace decisions
based on inspection data be associated to the best extent possible
with components in their current state and condition.
To simply illustrate the value of 3D visualization, consider the
case of two water sources merged into a common line. Process
data are included as text. Piping is initially color-coded according
to nominal stream temperatures. Reference data can be readily
available through hyperlinks.
FAC susceptibility values can be accessed to graphically enhance
areas of interest. In Figure 2, the reflected-light temperature colors
are mostly subdued and a red glow is emitted by areas of potentially
high damage rates. The application of both reflective and emissive
color spectra to the geometrically accurate representation of field
piping allows complex theoretical data to be visualized more easily
than through thousands of words of text or tabulated data.
A manager of a utility fleet inspection program noted that " having
3D models of the existing equipment to manage diagrams would
be huge, " for example, knowing if a section of replaced pipe is 1 foot
or 3 feet. Relying on the recall of site personnel or plant documentation
is often inadequate. The fact that 3D visualization technology
distinguishes insulation from piping is also deemed important, and
that each reducer or expander, each fitting, is a distinct entity and
can serve as an access point for associated data.
An engineering services manager for a large nuclear fleet
stated that the highest value point is linking the 3D models to
the computerized maintenance management system's work order
system. Similarly, providing pre-job training and practice briefs
would be helpful.
The manager further noted that nuclear units are very old,
and were designed on drafting tables. No 3D models exist for
most of the plant, and piping inspections are carried out with
2D isometrics. Some drawings have been scanned into AutoCad,
but they are not intelligent. Specific and persistent FAC issues
with feedwater heaters could really benefit from 3D visualization
because the shells have to be regularly checked and the heater
bays are crowded with " lots of stuff. " In addition, many areas of
piping susceptible to FAC are not accessible.
An asset director for multiple gas turbine cogeneration plants
reported, " We have been chasing FAC for 20 years. " This technology
could help convert hand-drawn isometrics to models of the
actual equipment and enable the shift from time/location-based
inspection strategies to condition-based inspection. ■
-Costantino Lanza is with INOVx Solutions, and Jason Makansi
is president, Pearl Street Inc.
April 2014 | POWER
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POWER April 2014

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