PetroChem E-ssentials Newsletter_June_2013

TÜV SÜD | Vol. 7 June 2013
PetroChem | Technical industry e-news updates essential to your operations
E-ssentials
http://www.petrochemintl.com
CONTENTS:
PetroChem Experts to Present at ICPIIT Conference 02
PetroChem Hosts Open House Events During ICPIIT
Conference
02
Nondestructive Testing: A Techniques Primer 03
Using Three-Dimensional Laser Scanning for Above-Ground
Storage Tank Integrity
04
An Overview of Pipes and Tubing Inspection Techniques
06

TÜV SÜD E-ssentials
Vol. 7 June 2013
Page 2
Editorial
DearReader,
WelcometothelatestissueofPetroChemE-ssentials,
thee-newsletterfromPetroChemInspectionServices,a
subsidiaryofTÜVSÜDAmerica.
ThereleaseofthisissueofPetroChemE-ssentials
coincideswiththe2013InternationalChemicaland
PetroleumIndustryInspectionTechnology(ICPIIT)
ConferenceXIII,whichbeginsonJune12thinHouston,
TX.TechnicalexpertsfromPetroChemInspection
Services,includingWilliamBobbittandIdamarieCarden,
willbeamongthefeaturedspeakersandpresenters
there.Ifyou’reattendingtheConference,Ihopethat
you’llfindtimetoattendoneormoreoftheseexcellent
presentations.Meanwhile,seethebriefarticleentitled
“PetroChemExpertstoPresentatICPIITConference”for
moreinformation.
PetroChemwillsponsoraseriesofOpenHouseevents
atourPasadena,TXheadquartersduringtheweekofthe
ICPIITConference.Seeourbriefarticle“PetroChemHosts
OpenHouseEventsDuringICPIITConference”formore
detailsaboutwhatwehaveplanned.Or,contactPatty
Sweetenat281-884-5187.Welookforwardtoseeing
youthere.
SpeakingoftheICPIITConference,I’llbedeliveringone
oftheConferencePlenaryAddressesonthegrowing
acceptanceanduseofnewnondestructivetesting(NDT)
methodsandtechniques.Toprovideourreaderswith
somebackgroundinformationonthissubject,we’ve
reprintedinthisissueour2011article“Non-Destructive
TestingTechniques:APrimer”toaidintheselectionof
appropriateNDTmethodsforspecificapplications.
ContinuingontheNDTfront,eddycurrenttestingand3D
laserscanningaretwoNDTmethodsgainingwidespread
useinrecentyears.Ourarticles“UsingThree-Dimensional
LaserScanningforAboveGroundStorageTankIntegrity”
and“AnOverviewofPipesandTubingInspection
Techniques”discusstheapplicationsandadvantagesof
eachoftheseNDTmethods.
Thanks!
GerhardAbel
President
PetroChemInspectionServices
PetroChem Experts to Present at ICPIIT Conference
Technical experts from PetroChem Inspection
Services will be among the featured speakers and
presenters at the upcoming International Chemical
and Petroleum Industry Inspection Technology
(ICPIIT) XIII Conference, to be held on June 12-15,
2013 at the Crowne Plaza Houston Northwest-
Brookhollow in Houston, Texas.
The ICPIIT Conference focuses on industry
innovations and solutions in the area of
nondestructive testing (NDT). The four-day event
offers technical sessions and exhibits addressing
a range of issues, including pipeline and piping,
pressure vessels, storage tanks, chemical and
refinery plants, equipment for transportation,
inspector certifications, codes, standards,
regulations, and risk-based inspections and
evaluations.
Gerhard Abel, President of PetroChem Inspection
Services, will deliver a Conference Plenary Address
on Thursday morning, June 13th. His address,
“Application of Various NDT Technology and Market
Acceptance of Next Generation Technologies,” will
provide an overview of the NDT technology choices
available to end users.
In addition to Mr. Abel’s address, PetroChem’s
William Bobbitt will discuss “Code Quality
Inspection Through Computerized Radiography,”
in a technical session scheduled for Wednesday,
June 12th, at 3:15pm. And PetroChem’s Idamarie
Carden will discuss “Three-Dimensional Laser
Scanning of Above-Ground Storage Tanks” on
Friday, June 14th at 1:30pm.
Additional information about the ICPIIT XIII
Conference and details about the Conference
technical program are available at https://www.
asnt.org/en/MajorSiteSections/Events%20and%20
Publications/Upcoming%20Events/ICPIIT%20XIII.
aspx.
PetroChem Inspection Services is a Gold Sponsor
of ICPIIT XIII, and will also be exhibiting at the
Conference. If you’re attending the Conference,
please stop by our exhibit booth #31, meet our
petrochemical industry experts, and learn more
about how PetroChem can help you address your
specific NDT testing challenges.
If you can’t make it to ICPIIT, we invite you to view
PetroChem’s product videos at http://petrochemintl.
com/videos.cfm. n
PetroChem Hosts Open House Events During ICPIIT
Conference
PetroChem Inspection Services will host two Open
House events at its Pasadena, TX headquarters
during the International Chemical and Petroleum
Industry Inspection Technology (ICPIIT) XIII
Conference, to be held on June 12-15, 2013.
The Open House events are scheduled for
Wednesday, June 12th, from 11am-4pm, and
Thursday, June 13th, from 3-8pm. Each Open
House event will include informative presentations
on advancements in nondestructive testing (NDT)
equipment and techniques, as well as plenty of
food, refreshments, and entertainment.
PetroChem will provide Conference attendees with
complementary shuttle transportation to its Open
House events from the Crowne Plaza Houston
Northwest-Brookhollow, the location of the ICPIIT
Conference.
PetroChem’s Open House events are an excellent
opportunity to learn more about our wide range of
testing and assessment services and capabilities,
and to discuss your particular challenges with our
technical experts in an informal setting.
For more information about PetroChem’s Houston
Open House, please contact Patty Sweeten at 281-
884-5187 or at Patty_Sweeten@PetroChemIntl.com.n

Vol. 7 June 2013
Page 3
Nondestructive Testing: A Techniques Primer
In the petroleum and hydrocarbon refining and
processing industries, nondestructive testing
(NDT) is an essential tool that can be used to
evaluate materials and systems while maintaining
and preserving costly plant and infrastructure
investments. However, there are a number of
NDT techniques from which to choose, each
utilizing unique technologies that are appropriate
for specific applications. This article provides an
overview of various NDT techniques and their uses.
REAL-TIME RADIOGRAPHY (RTR)
RTR uses low dose x-rays to produce images.
However, unlike conventional radiographic testing,
RTR captures images electronically rather than on
film. This approach all but eliminates the lag time
between initial exposure and the resulting image.
RTR testing units are usually lightweight portable
devices that include a highly sensitive x-ray
imager and a battery-operated x-ray tube, making
them ideal for portable field operation. These
devices are also typically equipped with electronic
recording capabilities that allow for the capture of
still images or video.
RTR is most commonly used for rapid inspection
of pipes, and is capable of scanning anywhere
from 100 to as much as 500 feet of pipe per day,
depending on the application. This speed allows
the inspector to quickly and economically identify
areas of concern that can be further examined
with more expensive testing methods. RTR is a
particularly useful technique in corrosion under
insulation (CUI) surveys, and can identify areas of
wet and saturated insulation.
RTR is also useful for inspecting welding locations
in insulated pipe, and can easily locate welds in
support of positive material identification (PMI)
programs. However, the use of RTR is limited to
pipes and insulation that do not exceed 27 inches
at the tangent.
GUIDED WAVE (GW) ULTRASONIC
INSPECTION
GW ultrasonic inspection involves the use of a
testing unit that generates ultrasonic energy. The
energy is directed down the length of a pipe and
returns to the transducer ring in the testing unit
in a pulse-echo fashion. Any change in the cross
section along the length of the pipe generates
reflected energy (i.e., ultrasonic signals) that can
be analyzed and used to identify areas of wall loss
within a pipe.
GW ultrasonic inspection provides 100% coverage
throughout the pipe’s test length, even when
only limited access is available. Therefore, it
is commonly used for in-service inspection of
otherwise inaccessible piping, such as elevated
piping or piping used at road crossings.
However, as a screening tool for piping, GW
testing provides qualitative but not quantitative
results. Defective areas that are identified using
GW testing require the use of complementary
testing methods or visual inspection to acquire
specific data. Further, a number of variables
affect the range and sensitivity of GW testing. For
example, travelling through bends distorts the
GW signal, making feature or defect classification
unreliable.
Electro-Magnetic Acoustic Transducers (EMATs)
Unlike conventional UT transducers, EMATs create
ultrasonic energy by inducing an alternating current
within a magnetic field. EMAT testing units have
two probes, a pulser and a receiver. The pulser
sends an ultrasonic signal in both directions around
a pipe’s circumference, and the receiver receives
the signals from both directions. Changes in the
UT signal represent changes in the piping material,
such as wall loss.
An EMAT inspection can be conducted on any
piping that is physically accessible, including
dock lines, sleeper racks and elevated piping. It
can detect small, isolated defects down to 1/8
inch in diameter, as well as generalized wall
loss from corrosion or erosion. EMAT also allows
for the rapid screening of long pipe lengths, and
can inspect as much as 1000 feet of piping in a
single shift while providing qualitative results
and identifying defect locations for follow-up
inspection.
PHASE ARRAY (PA) ULTRASONIC
INSPECTION
PA ultrasonic technology electronically modifies
the acoustic probe characteristics of conventional
transducers. PA testing units use multiple elements
in a single housing, excited at specific intervals,
to generate uniform wave fronts at specific
angles. Electronic images are then created from
the received ultrasonic energy, allowing for the
identification of defects and their location.
PA ultrasonic inspection offers high speed
electronic scanning without moving parts, and
can inspect multiple angles using a single,
electronically-controlled probe. Data can be
collected in either manual or encoded modes. Most
ultrasonic techniques for flaw detection can be
applied using PA probes.

Vol. 7 June 2013
Page 4
Using Three-Dimensional Laser Scanning for Above-Ground Storage Tank
Integrity
The use of three-dimensional (3D) laser scanning
technology to evaluate above-ground storage
tanks can provide owners and operators with a
significant amount of information regarding the
integrity of their storage tanks. Compare with other
types of data collection techniques, laser scanning
can generate millions of data points, ensuring
increased accuracy in tank evaluation. In addition,
advanced software can be used to facilitate the
verification of future laser scanning measurements
against baseline data. This article will describe 3D
laser scanning technology, its use in evaluating
above-ground storage tanks, and its benefits.
THE TECHNOLOGY
3D laser scanners typically incorporate a laser
source and a mirror assembly rotating at high
speeds. Light from the laser source is reflected
off the mirror in a programmed sequence, and
then travels until it encounters a targeted object.
However, environmental temperature can impose
limitations on the use of PA ultrasonic inspection,
due to the sensitivity of the small electronic
components and transducer elements used. Other
limitations on the use of PA ultrasonic technology
include the size of the transducer footprint, and
low amplitude responses from energy diffusing or
scattering reflectors, such as material porosity.
TIME OF FLIGHT DIFFRACTION (TOFD)
ULTRASONIC INSPECTION
ToFD is a multi-mode ultrasonic inspection
technique that measures the flight time of
the sound energy through the material under
inspection, from one probe to another. ToFD
ultrasonic inspection is typically used to inspect
welds and base material for flaws, cracks, root
erosion, corrosion and cladding conditions. It can
completely cover a typical butt weld, the heat-
affected zone (HAZ) and the base material adjacent
to the weld from a single position.
ToFD ultrasonic inspection can be performed in
less time than a manual ultrasonic inspection, and
can more accurately evaluate the through-wall
dimension of defects. ToFD inspection devices can
also produce an image that can be archived for
repeat inspection, as a tool for ongoing monitoring
of an identified defect. Perhaps most important, a
ToFD inspection does not interrupt production
compared to other radiographic inspection
techniques.
AUTOMATED ULTRASONIC TESTING
(AUT)
AUT is the automated robotic deployment of
conventional or advanced ultrasonics to produce
consistently articulated and encoded data. AUT
applications include weld and cladding inspection,
corrosion mapping, and inspection for hydrogen
induced cracking (HIC) and stress-oriented HIC
(SOHIC).
AUT-based inspections offer consistently
incremented and repeatable scanning, and
increased speed and accuracy of inspection. These
advantages enhance post-collection data analysis,
including fitness for service calculations. AUT is
also capable of calibration verification.
The limitations of AUT inspection largely reflect
the way in which AUT equipment operates. For
example, AUT systems typically use magnetic
wheels to secure them to equipment under test, so
surfaces must be clear of loose debris. In cases
where non-ferromagnetic materials are being
evaluated, tracks of some sort much be attached
to the material to hold the AUT in place. Finally,
AUT systems typically require power to operate the
electronics and motor controllers, although smaller
AUT systems may be operated with battery power.
Alternating Current Field Measurement (ACFM)
ACFM was originally developed for use on offshore
structures in the North Sea, and has been used in
the United States to inspect pressure vessels for
environmentally-induced cracking. ACFM-based
inspection equipment is capable of detecting and
sizing cracks in most metals, and can be used as
a replacement for conventional magnetic particle
and liquid penetrant testing.
ACFM can be used to inspect a wide range of
materials, including carbon steel, stainless steel,
aluminum, and nickel-chromium-based super
alloys. ACFM inspections do not require extensive
cleaning of inspected surfaces or the removal
of coatings. ACFM-based inspections are also
60-70% faster than conventional inspection, often
allowing rapid, single-pass inspection.
CONCLUSION
Each material and system inspection situation
typically presents a complex set of unique
circumstances and challenges. The proper
selection of an appropriate NDT inspection
technique must be made in that context, and
involves the careful evaluation of the specific
attributes and benefits of each technique. An
experience consultant can provide valuable
perspective and advice when it comes to
identifying the right inspection technology for each
situation.
For additional information about NDT inspection
options, or NDT inspection services offered by
PetroChem. visit www.petrochemintl.com. n
The light is then reflected off of the object and a
portion of the reflected light is picked up by the
scanner. Sensors within the scanner are then used
to compare the emitted light with the reflected
light, allowing the scanner to calculate the precise
dimensions of the object.
Modern laser scanners can collect as many as one
million measurements per second. Therefore, a
complete scan of a targeted object can consist of

Vol. 7 June 2013
Page 5
positioned in and around the tank at different
levels and locations within the scanned area.
Targets are used as guides to merge individual
scans. A minimum of three common targets should
be used to ensure accurate overlap of the scans
when they are merged, but a larger number of
targets will ease the merging process. Internal
and external scans can also be merged, again
requiring a minimum of three common focus points
between internal scans and external scans. The
resulting data is then merged using specially
designed application software, resulting in a true
3D rendering of the tank. Accurate measurements
between objects can then be calculated from the
3D image.
THE ADVANTAGES OF 3D LASER
SCANNING
The data collected from a 3D laser scan can
be used to calculate tank plumpness, “out-of-
roundness,” settlement, and other situations
requiring detailed measurements. Data can be
evaluated or reevaluated after the scan technician
has left the tank site, and can also be evaluated for
other purposes without an additional site visit or
an additional round of measurements. In the future,
3D scanning software applications are expected
to support the production of strapping and
calibration charts in real time, thereby eliminating
delays in tank assessment. In addition, software
enhancements are expected that will provide
accurate floor mapping and exact patch locations,
Figure 1: A 3D Image of a tank externally
THE SCANNING PROCESS
The objective of 3D laser scanning is to ensure
the collection of 100% of the data related to
the outside of the tank and the surrounding
containment area. At a minimum, scans should be
conducted from the north, east, south, and west
quadrants of the tank, as well as from the center
of the tank. The actual number of external scans
required in order to obtain a complete external
survey will depend on the number of obstructions
surrounding a tank, such as pipes, vehicles, and
other objects.
A typical laser scan requires a minimum of five
minutes per scan. Focus points (targets) are
millions of data points. The actual number of data
points that need to be collected will depend on the
scope of the tank inspection and the requirements
of the customer. However, a larger number of
collected data points will yield a higher resolution
image.
3D LASER SCANNING APPLICATIONS
In evaluating above-ground storage tanks, 3D laser
scanning can be used for a variety of different
assessments. The resulting image produced by
the scanner can be used simply to identify the
dimensions or placement coordinates of a tank.
In more complex assessments, laser scanning
can help determine whether a tank has tilted
or deformed over time due to use or internal
pressures. Using application software designed
expressly for the purpose, multiple scans produced
over an extended period can be compared to
identify the speed and extent of tank structure
changes.
Currently, 3D laser scanning is most commonly
used for the strapping and calibration of tanks,
measuring and calculating finite analysis on tank
bottoms, dike volume calculations, and shell
deformations. The images produced by 3D laser
scans enable a complete and thorough evaluation
of a tank bottom. Scan data is stored electronically,
and can be reexamined and reevaluated in the
future. This capability is especially useful when
comparing settlement evaluations and ground
movement of a tank foundation.
Figure 2: A 3D Image of the tank with internal components

Vol. 7 June 2013
Page 6
An Overview of Pipes and Tubing Inspection Techniques
a significant improvement over current manual
mapping methods.
It is important to note that accurate laser scanning
depends on calculating the time it takes reflected
light to return from an object to a scanner. The
effectiveness of the scan is compromised if the
object or area being scanned absorbs light, or if
the laser is refracted at an angle at which no data
can be collected. The distance limitation is 80
meters (approximately 266 feet).
CONCLUSION
3D laser scanning technology offers significant
advantages in the evaluation of above-ground
storage tanks. It can provide a detailed assessment
of a tank shell and tank bottom for deformations
and tank settlement, allowing for a more accurate
finite element analysis of the area. 3D laser
scanning can also be used for tank calibrations
to ensure that measured volumes account for the
full surface of the tank shell and bottom, including
all deformations. Finally, specialty software
applications provide effective and efficient
comparisons between multiple scans, easing the
task of evaluating tank changes over time.
PetroChem Inspection Services provides 3D laser
scanning services and evaluation in support of a
variety of above-ground storage tank applications.
For additional information about our capabilities,
visit our website at http://www.petrochemintl.
com/industry/petrochem.cfm, or contact us at
800-747-4099. n
From heat exchangers, condensers, and boiler
tubes to process coders and chillers, pipes and
tubing are critical components in a wide range of
petrochemical production and refining operations.
As such, the routine inspection and maintenance of
pipes and tubing is an essential task, as it helps to
minimize production shutdowns, reduces the risk
of environmental leaks and spills, and increases
worker safety.
There are a variety of nondestructive testing
techniques available to assess the integrity of
pipes and tubing. Techniques include Eddy Current
Testing, Remote Field Eddy Current testing (RFT),
Magnetic Flux Leakage (MFL) testing, Internal
Rotary Inspection System (IRIS) testing, and
Laser Optical Tube Inspection System (LOTIS)
Testing. The type of testing selected for a specific
application typically depends on the magnetic
properties (ferrous or non-ferrous) of the pipe or
tubing subject to evaluation, as well as the relative
cleanliness of the pipe or tubing.
The following sections summarize each of the
above techniques and their application in field
assessments.
EDDY CURRENT TESTING
Eddy Current Testing uses bobbin type probes to
induce electrical currents into pipe and tubing
materials. As the probe is guided through the
pipe or tubing, material defects, such as cracks,
pitting, and wall degradation disrupt the flow of
the electrical current, thereby signaling a problem.
Advanced eddy current testing systems can filter
out unwanted responses, improving the overall
quality of an inspection.
Eddy Current Testing is typically used with non-
ferrous materials, since they are less permeable
than ferrous materials. However, eddy current
technology is sensitive to a large number of
variables, and can be 3-4 times more efficient than
other inspection methods. These benefits make
eddy current testing a tool of choice for many
inspection applications.
REMOTE FIELD EDDY CURRENT TESTING
Remote field Eddy Current Testing uses a special
type of amplifier and probe that produces the
higher power fields required for the testing of
pipes and tubing made of ferrous or carbon steel
materials. Because remote field eddy currents
are transmitted through the wall of the pipe
or tubing, it is capable of detecting defects on
both the inside and outside diameters, although
accuracy decreases as the cross section of the
tube increases.
Like Eddy Current Testing, remote field eddy current
testing is less dependent on the cleanliness of the
pipe or tubing. However, remote field eddy current
testing is slightly less efficient than conventional
eddy current testing, since the speed at which
testing is conducted must be as constant as
possible in order to obtain the most accurate data.
MAGNETIC FLUX LEAKAGE TESTING
Magnetic flux leakage testing uses a strong
magnet inside the inspection probe. When

Vol. 7 June 2013
Page 7
DISCLAIMER
Allreasonablemeasureshavebeentakentoensurethequality,reliability,andaccuracyoftheinformationinthisnewsletter.However,TÜVSÜDisnotresponsibleforthethird-partycontent
containedinthisnewsletter.TÜVSÜDmakesnowarrantiesorrepresentations,expressedorimplied,astotheaccuracyorcompletenessofinformationcontainedinthisnewsletter.Thisnewsletter
isintendedtoprovidegeneralinformationonaparticularsubjectorsubjectsandisnotanexhaustivetreatmentofsuchsubject(s).Accordingly,theinformationinthisnewsletterisnotintended
toconstituteconsultingorprofessionaladviceorservices.Ifyouareseekingadviceonanymattersrelatingtoinformationinthisnewsletter,youshould–whereappropriate–contactusdirectly
withyourspecificqueryorseekadvicefromqualifiedprofessionalpeople.Theinformationcontainedinthisnewslettermaynotbecopied,quotedorreferredtoinanyotherpublicationormaterials
withoutthepriorwrittenconsentofTÜVSÜD.Allrightsreserved©2013TÜVSÜDAmericaInc.
Your PetroChem contacts worldwide:
|| PetroChem | Technical industry e-news updates essential to your operations ||
Europe
TÜV SÜD Chemie Service GmbH
Phone: +49 214 30-62653
Email: beate.seiss@tuev-sued.de
Web: www.tuev-sued.de/technical_installations/chemical_service
Americas
PetroChem Inspection Services, Inc.
Toll-free: 1-800-747-4099
Fax: 281-884-5199
Email: info@tuvam.com
Web: www.petrochemintl.com
traveling through a section of pipe or tubing, the
magnetic probe detects wall defects and other
discontinuities due to variations in flux distribution
generated by the probe. Magnetic flux leakage
testing is best used on ferrous or carbon steel
materials, and is less effective with aluminum
pipes and tubing.
INTERNAL ROTARY INSPECTION
SYSTEM TESTING
Internal rotary inspection uses an ultrasonic
beam to scan the entire length of a tube’s internal
service, monitoring echoes from the tube’s front
and back walls to produce precise measurements
of the tube wall thickness. However, measurement
precision is compromised when inside or outside
diameter deposits are present, or when pipes or
tubing are not extremely clean. For this reason,
internal rotary inspections are typically preceded
by “soda blasting” of the pipe or tubing targeted
for inspection.
Internal rotary inspections often take two to
three times longer than comparable remote field
Eddy Current Testing. In addition, internal rotary
inspections are not as sensitive as other inspection
methods to certain types of degradation, such
as cracking. It is recommended that degradation
and other anomalies identified by internal rotary
inspection be verified and confirmed with other
inspection methods before repair or replacement of
pipe or tubing is undertaken.
LASER OPTICAL TUBE INSPECTION
SYSTEM TESTING
A final method for inspecting tubes and piping is
laser optical tube inspection. This technique uses
light generated by a laser probe to create a digital
image of the tube, which can then be evaluated
and analyzed. However, the accuracy of a laser
optical tube inspection depends on a high degree
of tube cleanliness, and requires that the tube be
free of moisture. Otherwise, deposits and moisture
will compromise the quality of the data collected.
As such, laser optical tube inspection is the least
efficient of the inspection methods discussed here.
COMPUTER-BASED TOOLS TO ENHANCE
INSPECTION TECHNIQUES
Computer software used to process data generated
by the inspection methods discussed above has
advanced significantly in recent years, increasing
the overall value of pipe and tubing inspections
and also driving further improvements in
inspection methods. Now, large volumes of data
can be captured, stored, and evaluated, even at
the site of inspection, allowing for more detailed
examinations in real time. Data from multiple
inspections can also be more easily compared
and correlated, allowing the inspector to identify
trends and potential condition problems in advance.
Additionally, inspection reports can be quickly
generated, using standard templates or customized
report formats.
CONCLUSION
Today’s nondestructive testing and inspection
methods have significantly improved the practice of
pipe and tubing inspection, making the inspection
process more efficient as well as more accurate.
Combined with advanced software applications,
pipe and tubing inspection technologies have
reduced inspection-related production downtime
and increased the value of the overall inspection
process. These benefits support operator
efforts to improve the reliability of operations
and to minimize risks to worker safety and the
environment.
PetroChem Inspection Services is a leading
provider of nondestructive testing services for the
inspection and evaluation of pipes and tubing used
in petrochemical production and refining facilities.
For additional information about NDT capabilities,
visit our website at http://petrochemintl.com/
nondestructivetestingservices. n

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