Technical Bulletin # P-01
Evaluating Building Piping Systems
For Corrosion, Pitting And Remaining Service Life
THE PROBLEM:
A majority of commercial real estate
properties are now approaching 50 years of service; many have already exceed
that age. While most properties have upgraded or replaced their HVAC,
communication, and electrical services to meet modern demands, few have given
any consideration to the condition of the various types of pipe so critical to
the operation of their facility. Chemical water treatment, relied upon solely
to slow the rate of corrosion, often fails to provide the necessary protection
to ensure extended pipe life.
Test methods such as corrosion coupon
monitoring, spool pieces, and selective metallurgical analysis, will provide
information related to the corrosion rate over a fixed period of time, and for
a specific location. They fail, however, to provide sufficient information on
which a sound and reliable overall piping evaluation can be based. For many
facilities, corrosion monitoring is generally inadequate or ignored, often in
error, or simply nonexistent.
Given the many different forms of
corrosion which can coexist within the same piping system over time, corrosion
coupon or metallurgical testing often fails to present an overall view -
providing instead a general indication of what corrosion has recently taken
place at very specific locations.
THE SOLUTION:
Utilizing ultrasonic equipment and
detailed computer analysis, we can take extensive wall thickness measurements
throughout an entire facility. With a typical building evaluation being
comprised of 720 or more individual ultrasonic tests, we can produce a clear
and reliable evaluation of the interior piping condition - thereby providing
building owners and operators with the information they need to make both short
and long term maintenance and capitol planning decisions.
Unlike most other forms of pipe analysis,
ultrasonic testing is nondestructive, and does not require shutdown or any
special preparations. From our initial wall thickness measurements and a review
of your building history, we can derive valuable information regarding the
present state of each location tested. Information such as:
- Pipe Metal Loss
- Corrosion Rate
- Percentage Of Allowable Loss
- Remaining Pipe Life
- Estimated Retirement Date
- Pass/Fail Recommendation
- Overall Piping Condition
In addition, the information from all
test locations is combined into a series of summary graphs, which provide a
powerful tool for understanding the corrosion activity and trends within any
piping system. Each report provides the following summary graphs:
- Original Pipe Thickness vs. Measured Values
- Corrosion Rates
- Estimated Remaining Pipe Life
- Percentage of Allowable Pipe Loss
- Actual Pipe Loss
- Overall Pipe Status
- Corrosion Rate vs. Pipe Size
- Corrosion Rate vs. Physical
Location
In order to make the results of each
evaluation understandable, ECI presents the data in a clear and readable
format; organizing each report for the professional engineer, management
company, building owner, and layman alike.
All information derived from testing a
typical facility is detailed, summarized, graphed, and evaluated in a full
color 100 page report. Each report also includes background information on the
testing process itself, an explanation of all factors and assumptions
influencing the final results, sample calculations, and a summary chapter of
conclusions and recommendations. Ours has been described by consulting
engineers and building operators as, "the most
thorough and informative pipe evaluation available."
A color coded bar graph for each test
location shows the result of all 12 wall thickness measurements taken for
record, and indicates the level of pitting activity found at each location. The
more even the wall thickness profile across the horizontal axis, the less
corrosion and pitting likely exists. An uneven thickness profile as shown
below, common to most condenser water systems, would quickly indicate a higher
corrosion rate and random pitting conditions.
A 3D bar graph quickly summarizes the
current status of each test location by comparing measured average and minimum
wall thickness values vs. the initial pipe wall and minimum allowed dimensions.
This graph is often viewed as the key piece of information describing the
status of any test location.
Average and worst case corrosion
scenarios offer alternative viewpoints for each set of test data provided - in
this case estimating current thickness, metal loss, corrosion rate, and future
retirement data for a 27 year old, 20 in. diameter extra strong condenser water
pipe, located at the roof level, and having an original wall thickness of 0.500
in. As pitting activity increases, worst case scenario predictions become more
important.
All information relative to each test
location is submitted in a single and concise data page, shown below. An
exploded view of this same data page, with further explanation, can be found
under the heading
Testing Services -
Ultrasonic Pipe Testing at the Testing Services menu.
All accumulated data is then graphed
according to a variety of criteria. The below summary graph shows the
relationship between the average and minimum measured wall thicknesses and the
original pipe wall thickness over 25 different locations tested, and is typical
of the level of detail and accuracy provided in every ECI report.
In this condenser water evaluation (based
upon a separate data set from the above examples), various diameter pipe
between 10" and 3" was tested, thus the rear descending grey base line.
Ultrasonic testing showed a relatively even corrosion rate throughout all pipe
sizes at the locations tested; with mild pitting present as evidenced by the
lower profile of the red minimum pipe thickness value. Actual wall loss is
shown consistent throughout the condenser system.
A far more detailed explanation of our
testing and reporting procedures can be found under the heading
Testing Services -
Ultrasonic Pipe Testing at the Testing Services menu.
East Coast Industries, Inc. offers a
complimentary analysis report for any single pipe location. This provides
potential clients the benefit of being able to evaluate our testing and
reporting methods based upon information derived directly from their own
building property. See Technical Bulletin
# P-04 regarding free limited UT testing.
Testing
Services