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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, communications, elevator, pneumatic, and electrical services to
meet modern demands, few have given any consideration to the condition of the
various types of pipe so critical to their daily operation. Such concerns are
often first raised only after a leak or some other water related problem
occurs.
Chemical water treatment, relied
upon exclusively to slow the rate of corrosion and keep the piping clean, often
fails to provide the necessary protection to ensure extended pipe life. The
various forms of corrosion monitoring available rarely indicate actual pipe
conditions, and cannot offer any estimate on remaining service
life.
A corrosion problem at a fire
sprinkler system, more than just a leak problem or the need to replace pipe,
can actually threaten the lives of many due to that same rust product clogging
the pipe and rendering useless the entire fire protection system. For sprinkler
piping, where corrosion is not generally recognized nor tested, a water leak
can actually be a benefit in signaling a corrosion problem prior to a true fire
emergency.
Test methods
such as corrosion coupon monitoring, x-ray, spool pieces, and selective
metallurgical analysis, will provide some information related to the corrosion
rate over a fixed period of time, and for a specific location. They fail,
however, to provide sufficient information upon 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, a thorough and accurate evaluation means is therefore required.
Read more about
various pipe testing options
available.
Corrosion coupons,
the most commonly used testing method in use, often fail to present an adequate
view of piping status. They provide instead a general indication of the
corrosivity of the water, an estimate of corrosion activity at very specific
test loop locations, and short term results only over a very narrow test
period. They do not, however, indicate the most important information desired -
which is the wall loss occurring at the piping interior itself.
Read more about the
limitations of corrosion coupons.
Considering all
available methods, only ultrasonic testing offers the ability to achieve a cost
effective, wide ranging, and informative piping evaluation. By utilizing
ultrasonic diagnostic equipment and detailed computer analysis, it is possible
to take extensive wall thickness measurements throughout an entire facility.
With a properly performed piping
evaluation being comprised of 500 or more individual ultrasonic tests per
individual piping system, a clear and reliable determination of the interior
piping condition can be produced. In almost all cases, a thorough ultrasonic
investigation will provide building owners and plant 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 a system shutdown or any special preparations. From an initial set of
wall thickness measurements and review of the building or plant history, it is
possible to derive valuable information regarding the present state of each
location tested. Information such as:
- Pipe metal loss
- Corrosion rate
- Percentage of
allowable loss to minimum standards
- Remaining pipe
service life
- Estimated
retirement date
- Pass or fail
recommendation for acceptable condition
- Overall piping
condition
In addition, the
information from all test locations can be combined into extremely informative
summary graphs - each of which will provide a powerful tool in understanding
the corrosion activity and trends within any piping system. Given sufficient
wall thickness testing, it is possible to create graphs allowing the comparison
of:
- 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
- Differences in
supply or return service
- Corrosion rate
vs. pipe orientation
- Differences in
new and older piping
Key to any form
of investigation is the need to be thorough, accurate, conclusive if possible,
and clear and organized in the final presentation of results. Due to the number
of individuals likely involved in the information chain, and having interest in
any piping problem, the report should be understandable to the professional
engineer, management company, building owner, plant operator, and layman alike.
In other words, a spreadsheet full of raw test data for the client to interpret
should never be considered acceptable.
The
below graphic, taken directly from a typical ultrasonic testing report
performed by CVI, illustrates the level of detail provided for each and every
piping area investigated. Each section of this compressed graphic can be
exploded for a better view by simply clicking on that area of the frame.
A graphical
summary of an ultrasonic piping evaluation provides a tremendous volume of
useful information - often tying the entire investigation together in one clear
picture. The below graph shows the relationship between the average and minimum
measured wall thicknesses as compared to original pipe wall thickness over 25
different locations tested. Trending of test results is possible only given
sufficient data points to plot.
In this
condenser water evaluation of a New York City office property (based upon a
separate data set from the above example), various diameter pipe sizes between
10" and 3" were tested - thus the rear descending grey base line of original
wall thickness as pipe size reduces. In this investigation, 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 as very
consistent throughout the condenser system, and suggests that other points, not
tested, will likely exist having similar losses.
Overall,
ultrasonic testing offers the greatest amount of accurate and reliable
corrosion rate and remaining service life information available. It is
unquestionably the major starting point to identifying the severity and extent
of any pipe corrosion problem, and will provide benefit to any follow-up
investigative work. Any further testing is always far more relative and
informative if based upon prior ultrasonic data.
While we believe that the primary benefit
of ultrasonic testing is its ability to produce the most through piping
evaluation, its low comparative cost is also a significant factor. A typical
ultrasonic evaluation cost of $100 per section of pipe offers significant
savings when compared to the costs involved with shutdowns, removing and
replacing pipe, and a metallurgical analysis - often near $4,000 per individual
sample.
For the price of evaluating one
section of pipe through metallurgical lab analysis, ultrasound can often
provide precise and detailed information on 35 different locations, or more - a
tremendous benefit to any building owner or plant operator in need of firm and
reliable information. Review a sample
ultrasonic report.
CorrView
International, LLC provides ultrasonic testing in our local New York area, as
well as throughout the United States. We have a team of qualified and certified
Level II NDT inspectors available to address any pipe corrosion problem
nationwide. With sufficient preparation , we can address corrosion issues
outside the United States as well.
Fees
are in the range of $100-$125 per each general piping location tested, with any
necessary travel expenses additional. Most ultrasonic testing evaluations
involve between 30 and 75 test locations, and provide the highest degree of
information not found elsewhere.
Typical
UT testing costs will range between $2,500 and $6,500 - the equivalent of
cutting out and metallurgically testing 1-2 pipe samples. We recommend
dedicating at least 20 test areas at any one piping system, at exclusively the
condenser water system, for example, in order to provide a representative and
reliable final report. Typically, 20-30 individual locations can be tested
during a normal work day - with our progress generally determined by building
and piping layout, insulation, pipe quality, on-site assistance.
We offer samples
pages of actual ultrasonic test reports in Adobe PDF format from our
Documents Download
Page. A full specification covering ultrasonic field testing and
reporting procedures is also provided for those interested in a better
explanation of our testing work, or for those requiring a firm definition of UT
work they are contracting.
For further
information on ultrasonic pipe testing services, please contact
CorrView
International, LLC.
©
Copyright
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