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Over the past 10
or more years, the principal of CorrView International has provided ultrasonic
testing services to many of New York City's largest office building properties.
These include the General Motors Building, The World Trade Center, Met Life,
The Pan Am Building, The Daily News Building, Federal Reserve Bank of New York,
The New York Stock Exchange, and Carnegie Hall, among others.
We have provided testing services to most
of the major real estate management firms, and have worked through some of the
largest consulting engineers in support of projects locally, as well as
throughout the United States.
As a result
of this work, we have developed and refined a testing and reporting procedure
that we believe provides to our clients the most comprehensive and useful
piping evaluation report available. We offer this specification below for those
individuals interested in better understanding the scope of work provided by
CVI, or for those looking to specify such a level of investigation under open
bidding conditions.
This pipe testing
specification is also available in Adobe PDF format, WordPerfect, Microsoft
Word, and basic ASCII text from our Documents Download
Page.
Prior to the
actual testing, CorrView International, LLC shall, where possible, conduct a
full walk through inspection of the subject location, and review the operation
of the piping system(s) in question. Specifics such as material type, pipe
size, pipe construction, operating pressure, and general physical condition
shall be determined.
Operating parameters
such as previous mechanical maintenance history, hours of operation, internal
fouling, accumulated deposits, quality of water treatment, etc., shall be
noted. A review of each system layout shall be made based upon existing piping
specifications and blueprints, as well as any supplemental information
available through the engineering department, or professional engineer.
An historical review of any prior leaks,
obstructions, or failures at the subject piping system(s) shall be made with
the engineering department. Areas where a specific concern for the integrity of
the piping exists by building operators and representatives shall be noted as
probable test locations. Visually observed examples of outer pipe corrosion or
leakage shall be highlighted as probable test locations.
Where an on-site walk through cannot be
performed, or judged as not necessary, information shall be gained as best
possible through blueprints, floor plans, or other documents, and from
interviews or information supplied by building property operators to best
illustrate the layout and operation of the subject
property.
Based upon the number of piping
locations to be tested, a general plan of action shall be proposed, and testing
fees quoted. Depending upon specific job requirements and conditions, every
effort shall be made to produce an evaluation comprised of:
- Largest and
smallest piping sizes
- Top and bottom
extremes of the system
- Horizontal
extremes of the piping layout
- Main lines and
distribution piping
- Risers and
horizontal runs
- Welded,
threaded, or clamped pipe
- Areas of no
flow
- By-pass
lines
- Pipe serving
alternating equipment
- Roof level
piping
Every effort
shall be made to reach representative types of piping in order to produce the
most informative report. The client shall provide the personnel necessary to
direct CVI to such areas in a timely manner.
Field testing shall be performed using a
Panametrics 37DL
Plus, 37DL Plus, or equivalent ultrasonic thickness gauging device.
The instrument shall have an on-board waveform display allowing its operator to
instantly evaluate the validity of each and every wall thickness measurement
taken, and have data logging capability.
All wall thickness measurements which do
not show an acceptable waveform pattern shall be discounted, and further
investigation made to identify the cause for the problem. Measurements showing
an acceptable waveform display and indicating an accurate wall thickness value
shall be saved for later download and analysis. Both the wall thickness value
and the accompanying waveform display shall be saved in the memory of the 37DL
Plus or equivalent device for future reference and re-evaluation, if necessary.
Equipment requiring the written recording of thickness values shall not be
acceptable.
The measurement instrument
shall feature "echo to echo" technology allowing the measurement of
coated or painted pipes without scraping, sanding, grinding, or otherwise
potentially removing outer metal from the test surface, or defacing client
equipment. A Panametrics D794 dual crystal element straight probe transducer,
or equivalent, shall be used in order to provide the highest wall thickness
accuracy possible, and to locate interior pitting.
This probe shall have a frequency of 5.0
MHZ and a tip diameter of 7.2 mm. A coupling agent of glycerine or its acoustic
equal shall be used to facilitate the transmission of the ultrasound signal
into the test surface. The appropriate high temperature couplant based upon
operating temperature shall be used for steam, steam condensate, and hot water
piping.
Instrument calibration shall be
performed at the beginning of the test session and at regular time intervals
throughout the investigation. A calibrated test block of the material to be
evaluated and having reference thickness steps above and below the minimum and
maximum anticipated pipe wall thickness to be tested shall be used. The test
block and instrument probe shall be allowed to equalize to the temperature of
the test medium before calibration.
Re-calibration shall be performed
whenever a change in temperature of the medium occurs. Re-calibration of the
instrument and probe shall also be performed after each hour of use, whenever
the instrument is turned off and on, or when pipe of a different diameter and
wall thickness is measured.
A preliminary
review of each test location shall be performed to generalize the condition of
that particular area. A minimum of 12 wall thickness readings shall be taken
and saved to memory for use in the final analysis of the test location. When
possible, those 12 measurements shall be taken at 3, 6, 9, and 12 o'clock
positions around the circumference of the pipe, and at three cross sections
along the length, each separated by approximately 3-4 inches.
Under conditions where the entire pipe
circumference is not available, or where conditions do not allow, measurements
shall be taken at random, but with evenly spaced intervals as best possible.
Measurements shall be identified as being taken at random or based upon the
above referenced standard grid in the final report.
A photograph of each test location shall
be taken in order to illustrate the general test area location and supplement
the written description. All relevant information regarding the location,
operating conditions, observed problems, etc. shall be noted for incorporation
into the final report. All observed piping related problems such as thread
leakage, outer surface corrosion, weld failure, and insulation failure, etc.
shall be noted for incorporation into the final report. A photograph shall be
taken to document the specific test location, or to document a failure event or
condition.
Small 8 in. to 12 in. sections
of insulated or covered pipe surfaces shall be removed in order to provide
access, if necessary. The removal, replacement, and re-painting of any
insulation or pipe covering shall be the responsibility of the engineering or
property management. Asbestos covered pipe will not be tested until properly
abated.
A final written
report shall be produced following the completion of the field testing, and
incorporate all compiled data. No measured data derived from the field testing
shall be discounted, amended, or falsified. Excepting clear examples where
error on the part of the ultrasound technician or test equipment has produced a
false wall thickness measurement, as verified by a review of the saved
waveform, all test data shall be incorporated into the final report.
An attempt shall be made to explain all
data anomalies. The report shall be available within 21 days following
completion of the actual field testing. The report shall be separated into
sections of summary and detailed information in order to suit the information
needs of various potential readers. The final report shall be written in a
clear and easily understandable format, shall be arranged in a logical
progression, and provide a full explanation of all accumulated data and derived
statistics.
Specifically requested
information from the client falling outside the general scope of the report
shall be incorporated into the final report to the best degree possible. An
executive summary shall be produced condensing the most important findings of
the report, as well as any specific highlights of the investigation.
An introductory report section shall be
provided detailing the testing procedure and instrumentation used. It shall
also include a listing and explanation of any assumptions made during the
testing and reporting procedure, as well as any investigative limitations
created by either the testing procedure, pipe medium, physical access,
availability of physical data relative to the pipe, or actions of the client.
Definitions of any specific technical terms and labels used in the report shall
be provided.
A preliminary statistical
summary section shall be provided showing overall measured corrosion rates,
pipe loss, remaining pipe life and retirement dates of all test locations. A
breakdown of the number of locations tested and corrosion statistics per each
piping system tested shall be provided.
Detail for each individual test location
shall be compiled providing all measured and calculated data. Full physical
identification of the pipe and piping service shall be provided. A photograph
of the location shall be included with highlighted indication of the general
test area. All 12 measured ultrasonic test values shall be graphed to provide a
visual representation of the variation at the interior pipe surface.
Test locations shall be organized and
presented in the final report in order to produce the best understanding of
piping conditions. Where an investigation involves multiple piping systems, the
data shall be organized and presented in the report according to each separate
piping system; with all relevant corrosion rate and retirement date statistics
generated for each individually. The report shall be printed in color.
The original wall thickness of the pipe
shall be determined, and estimated to be at industry specification, or above or
below industry specification. It shall be noted as such in the report. The
minimum allowable wall thickness for each individual location shall be
calculated based upon the particular pipe diameter, operating pressure,
construction (E value), material (S value), schedule, and pipe service
provided.
Two alternate corrosion rate
and remaining life prediction scenarios shall be calculated for each test
location. An "Average Case" scenario shall be presented based upon the
average of all measured wall thickness values, and provide estimates for the
following parameters:
- Average wall
thickness
- Average
corrosion rate
- Percentage of
allowable loss
- Remaining pipe
life
- Retirement
date
- Overall pipe
condition
An alternate
"Worst Case" scenario shall also be presented based upon the single
lowest measured wall thickness value found within the 12 measured values, and
shall provide minimum estimates for the same parameters as highlighted above. A
block graph showing the relationship between original pipe wall thickness,
minimum allowable wall thickness, average measured wall thickness, and minimum
measured wall thickness shall be provided for each test location. A comments
section offering any additional information, details, or explanation about the
test location or results shall also be provided.
All data points for each piping system
shall be graphed together in order to show the relationship (or lack thereof)
of the accumulated wall thickness measurements and calculated corrosion rate
and remaining life estimates. Graphs shall utilize both average and minimum
measured wall thickness values and be presented in color in order to clearly
display the relationship between each series of values.
Summary graphs shall be produced showing
the following trends and relationships:
- Original pipe
wall thickness vs. measured values
- Average,
minimum, and maximum corrosion rates
- Remaining pipe
life based upon average and minimum values
- Percentage of
allowable pipe loss
- Actual wall
thickness loss
- Breakdown of
overall piping status
Depending upon
the scope of the testing program, various modeling scenarios shall also be
investigated to show relevant trend comparisons. Modeling comparisons which add
insight and understanding to this report shall be submitted. Possible modeling
comparisons may include:
- Corrosion rate
vs. pipe size
- Corrosion rate
vs. physical floor location
- Corrosion rate
vs. pipe age
- Corrosion rate
vs. horizontal or vertical orientation
- Corrosion rate
vs. pipe material
- Corrosion rate
vs. pipe use
A calculation
shall be made for each test location and set of 12 wall thickness measurements
for the purpose of indicating the level of pitting activity which may exist.
Since any spot check of a piping system is not likely to locate the one lowest
wall thickness value of that area, the standard deviation of all measurements
shall be produced, from which a theoretical minimum wall thickness can be
calculated.
A priority worksheet of all
test locations shall be provided listing in order those locations having the
highest amount of metal loss. This worksheet will offer writing space for
engineering or building personnel to note any corrective actions or further
testing performed at each location. For multiple piping systems, individual
priority listings shall be provided.
A
written summary section shall be provided to review the entire report and
consolidate its contents into its major generalizations. The most significant
findings and deficiencies identified through the investigation will be
highlighted. Recommendations specific to the findings in the report shall be
provided. General recommendations for good corrosion control in HVAC related
piping systems shall also be provided, along with any other relevant and useful
information.
An explanation of all
mathematical calculations used in the preparation of the report shall be
provided in order that interested individuals can verify and reproduce the
calculations of corrosion rate and prediction of retirement date. An appendix
section shall provide all supplemental information relative to the accumulation
of data, and preparation of the report.
Observed problems or other information
noted during the course of the ultrasonic testing investigation shall be
documented. The report shall be clearly written and presented in a bound format
with the primary objective of providing the greatest amount of useful
information about the subject system to the client.
The report shall be made available on IBM
compatible computer format in order to enable the client further manipulation
or modeling of the data, or for other management purposes. At request, all
statistical data of the report shall be supplied in either database format
(dBase IV), spreadsheet format (Excel, Quattro Pro, or Lotus 123), or in
universal language (ASCII), and provided on CD-Rom. Major sections of the
report shall be made available in Adobe
PDF.
The full report shall be archived by
CorrView International, LLC in its original computer format for a minimum
period of five years, or longer if requested. Additional copies of the report
shall be available for as long as the data is on archive, at additional cost.
Follow-up investigations of the same
piping locations shall include test data from the most previous report; with a
series of calculations performed showing differences in wall thickness and
corrosion rate.
Additional information
related to ultrasonic pipe testing, its benefit and capabilities, can be found
elsewhere on this Internet site. See Technical Bulletin
P-7 regarding ultrasonic pipe testing. Excerpts of actual client
reports are available in Adobe PDF format from our
Documents Download
Page. Review a sample
ultrasonic report.
CorrView
International, LLC is interested in developing mutually beneficial
relationships with independent UT professionals throughout United States.
Explore the benefits
of an affiliate UT testing relationship with CorrView International,
LLC.
©
Copyright
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