Sample Report - Tank Testing
The goal of every ECI tank inspection is
to thoroughly answer the question(s) which first prompted the inquiry, and to
provide a clear evaluation of remaining service life. Due to the size and
critical role of many tanks in day to day mechanical operations, many operators
of older buildings have the interest to identify their current corrosion
status. For others, it is a leak or some other evidence of a corrosion
condition, which prompts special investigation.
Our evaluation provides a full
explanation of the testing procedure used, basic testing theory, background
information, calculations, assumptions, unknowns, and other significant
details. Each tank is reported upon within a separate section or heading - with
each section providing an executive summary, overview, raw test data, and
calculations for average and minimum corrosion rates, wall loss, percent of
allowable loss, pitting activity, and retirement dates, etc.
A sample of the most important
information provided for each tank tested, the detail and calculation pages, is
represented below. Due to the limitations of reproducing an accurate copy of
the actual 8-1/2 x 11 page within this frame, we have broken out the page for
an expanded view. Simply move the mouse over any area and click to view it in
greater detail. Click the expanded image to return to this page.
While some individuals may never read a
status report past the basic summary pages, in fact, most of our clients take a
keen interest in the details of our findings. For that reason, ECI presents a
comprehensive set of detail sheets for each location tested. These detail pages
provide all data and statistical calculations associated with our investigation
in a compact, well organized, and understandable format. The following two
pages are actually the most important of each report.
While the corrosion rates at different
surfaces rarely vary to any significant degree, separate retirement date
calculations are necessary due to different starting wall thickness values.
Therefore the data presented in the above summary page is expanded in further
detail for the shell and heads, or the bottom and side walls. Pitting activity
will also vary at different interior surfaces, and especially at top and bottom
locations, thereby demanding further more detailed calculations.
For every ECI ultrasonic tank testing
investigation, data is presented showing:
- Original Wall Thicknesses
- Minimum Allowed Wall Thicknesses
- Average And Minimum Wall Thickness
Measurements
- Actual Wall Losses
- Estimated Corrosion Rates
- Percentage Of Allowable Loss
- Estimated Remaining Service Life
- Overall Test Result Status
- Calculations Based Upon Average, Minimum,
And Lowest 5 Measurements
By performing hundreds to thousands of
wall thickness measurements at each tank location, ECI can produce a
representative profile of the interior tank surface. While it is obvious that
even a few thousand wall thickness measurements would never cover every square
inch of a tank surface, we have found that it does provide a good visualization
of conditions when graphed in three dimensions, and will provide an indication
if whether more intense investigation is necessary.
A high number of thickness measurements
also increases the probability of discovering random pitting conditions which
may be present, and/or corrosion trends due to varying liquid levels.
In the below illustration, taken from a
different set of data for a domestic cold water storage tank, we can very
clearly show a line of deterioration across the horizontal axis of the subject
tank. Here, testing was performed every 3 in. along the horizontal axis, and 4
in. around the shell circumference - for a total of approximately 1,850 wall
thickness measurements. The view of the graph is looking at the left and right
side halves of the tank respectively, with the downward perspective showing the
tank surface interior. The pink to violet coloration shows the greater amount
of wall thickness existing above the high water mark.
A 90 degree side wall profile of the same
above data, shown below, more clearly illustrates the corrosion penetration
into the tank wall. Perspective here is looking downward from the inside of the
tank toward the exterior wall. Furthermost corrosion penetration is at
approximately 0.200 in. from the outside of a tank originating at 5/15 in. or
0.3125 in. The top portion of each shell half is again shown in the pink to
violet shades toward the center of the graph.
Below, a 90 degree side wall profile of
the tank heads shows the exact same corrosion profile as found at the tank
shell - confirming the varying water level as the source of the corrosion
loss.
For each ECI ultrasonic testing report,
data is graphed in order to present the best possible understanding of its
condition. This often includes views for:
- Shell And Heads Of Round Tanks
- Side And Bottom Of Square Tanks
- Side And Bottom Of Cooling Tower Pans
- Side And Elevated Profile
- Underside Profile
Overall, every ECI tank investigation offers a
tremendous amount of information and value. Whether planning the purchase of a
new property or the renovation of an old one, whether responding to a suspected
corrosion problem, planning future capitol projects, or just fulfilling the
interest to know current equipment status - East Coast Industries, Inc. can
provide the answers.
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