Magnetostrictive Sensor(MsS) System · Magnetostrictive Sensor(MsS) System For Guided Wave Testing...

Guided Wave Analysis LLC http://www.gwanalysis.com Tel: 1-210-842-7635 email: [email protected]

Magnetostrictive Sensor(MsS) System

For Guided Wave Testing of Pipeline

Guided Wave Analysis LLC supports clients with

Sales and Rental of MsS Guided Wave System,

Training, and Consulting

For information or inquires:

Log on to http://www.gwanalysis.com

Email to [email protected]

Guided Wave Analysis LLC http://www.gwanalysis.com Tel: 1-210-842-7635 email: [email protected] 2

The main purpose of establishing Guided Wave Analysis LLC (GWA) in 2007

is to spread MsS technology worldwide through training and consulting in order to

ensure proper use of the MsS technology. The technology incorporated in the MsS

System was developed by Southwest Research Institute® (SwRI®), a Texas nonprofit

corporation.

The MsS System was commercialized primarily for inspecting and monitoring

pipeline. It is used to generate a non-dispersive guided wave for long-range ultrasonic

inspection and monitoring through rapid surveying of pipes to detect internal and external

corrosion. The application areas of the MsS system are to inspect and monitor:

- Piping systems in oil, gas, and petrochemical facilities

- Offshore piping systems/risers

- Power generation piping systems

- Road crossings/levee penetrations

- Elevated or complex piping systems with limited clearance

- Buried pipelines

GWA sells and leases MsS Systems to NDT service companies, research institutes,

and universities, and supports these clients with consultancy, data analysis, supply of

accessories, personnel training, and on-site training and demonstration. The experience and

knowledge obtained from client support are used for upgrading MsS technology through

research and development at the Sensor Systems and NDE Department in SwRI®.


The MsS System is a device that electromagnetically generates and receives

ultrasonic waves in the material for long-range guided wave testing. It is composed of a

laptop computer, the MsSR3030R instrument, and MsS probes as shown in a photo below.

The MsS software in the laptop computer controls parameters of the MsSR3030R, acquires

data through a USB port, analyzes data, and generates inspection report. The MsSR3030R

instrument generates tone-burst electric pulses to the MsS probes and detects induced voltage

generated when the ultrasonic guided wave passes through the probe.

The MsS probe is an ultrasonic transducer consisting of ferromagnetic strips (0.10 mm thick)

and ribbon cables (less than 4 mm thick) as shown in the photo. The ultrasonic wave is

generated in the thin strip and coupled to the pipe through dry coupling, shear couplant, or

epoxy bonding.

MsS Sector Probe

The MsS sector probe is 4– to 12-inch-long,covering only section of pipe circumference, and

is used for medium range (5 to 20 ft) high-resolution inspection. It is used for inspecting pipe

support or pipe shoe area, wall penetration pipe, soil-air and concrete-air interface of pipe,

and 16-inch-OD or bigger diameter pipe including plate. Because the sector probe covers

only section of pipe, its sensitivity is very high, not depending on the pipe size.

MsSR3030R

MsS probe


MsSR 3030R System

Two channel transmitters and receivers for controlling the wave propagation direction

120 V or 240 V AC, 50/60 Hz, power or internal battery operated; The internal batterysupplies power to both equipment and computer for operating more than 2 days innormal operation with more than 50 inspection locations

Wide frequency range operation: 5 kHz to 250 kHz

The system has band pass filter at 16, 32, 45, 64, 90, 128, 180, and 250 kHz

The MsS probe can be installed with 25 mm or higher clearance aroundthe pipe and 75 mm clearance along the pipe.

The MsS probe can be installed if the pipe is accessible more than 60 percent around thepipe circumference. The heat tracer lines do not need to be lifted.

Two operation modespulse-echo mode: normal guided wave inspection and monitoringpitch-catch mode: guided wave inspection of high-attenuation pipe

Time-corrected gain (TCG) function that increases signal-to-noise ratio of long-distancesignal

Probe is very light (less than 0.8 kg for 24-inch pipe testing probe)

Light instrument (12.5 kg)

Software functions

- Sorting out false calls due to multiple reflections

- Multi-frequency data analysis for finding different size of defects

- Spectrogram data display for showing frequency response of indication

- Automatically finding indications


MsS Guided Wave System can inspect a pipe of any diameterincluding plate (usually 0.25- to 80-inch outer diameter)

The total cross-sectional wall along the pipe is inspected. (Volumetric inspection)

Ability to detect corrosion wall loss and cracks in aboveground, buried, and insulated pipe.

Inspection range in straight above ground pipeline is typically 50 meters on either side of the MsS probesand can be up to 200 meters in ideal conditions.

Sensitivity can be as good as 1% cross sectional loss in good condition of pipe (but the threshold can beset from 0.5 to 5 % depending on the distance from the MsS probe and pipe condition).

The generated signal with MsS probe is 56 dB (600 times) higher than the coherent noise of unwantedmodes.

MsS probes can be attached to a pipe with dry coupling, epoxy bonding or ultrasonic shear couplantdepending on pipe surface condition.

Inexpensive MsS probes can be permanently installed to pipeline at difficult-to-access location for long-term pipe monitoring.

Continuous probe covering the whole circumference of pipe- Excellent direction control- Zero near-field length

MsS probe has short dead zone length- 11 inch with 32 kHz probe- 8 inch with 64 kHz probe- 5 inch with 128 kHz probe

A pipe of up to 300 oC surface temperature can be inspected and monitored without taking it out ofservice if the MsS probe is bonded at a temperature less than 125 oC.

A pipe of up to 500 oC surface temperature can be inspected without removing heat tracer lines with MsSdry coupling (mechanical coupling) tools.

User-friendly analysis software reduces false calls and helps making inspection report.

Once the probe is installed, the inspection or monitoring can be done 20 or 30 locations a day withinstalled probe. It is cost effective and best for condition-based monitoring.

High-sensitivity pipe inspection with high-frequency (50 ~ 250 kHz) probe

Long-range pipe inspection with low-frequency (5 ~ 50 kHz) probe.


The guided wave is structure-borne ultrasonic waves that propagate along the structure

confined and guided by its geometric boundaries. As shown in the Figure 1, the guided wave in

the pipeline propagates along the pipe axis and reflects from any local cross-sectional area change

such as corrosion defects. The GWT is a technique for finding defect location with the arrival

time and the velocity of guided wave and estimating the defect size with the signal amplitude.

The GWT uses low-frequency of from 5 to 250 kHz in order to have a long wavelength that is

usually longer than the pipe wall thickness and to less attenuation for long-range inspection

How can inspector perform the Guided Wave Testing?

The MsS equipment for guided wave testing or long-range ultrasonic testing is compact

and easily operated by inspectors in facilities. Like ordinary ultrasonic thickness measurement

tool, inspector can carry it to the pipe and quickly test the pipe using MsS probe and shear

couplant. The surface preparation of guided wave testing is the same as that of ordinary ultrasonic

inspection except that we need to access to the whole pipe circumference for long-range

inspection. If MsS sector probe is used, the guided wave inspection of pipe is the same as the

ordinary UT thickness measurement in preparation and procedure. The only difference is that the

guided wave testing check defects along the axial length of pipe instead of wall thickness

direction.


The big advantage of guided wave testing is that the ultrasonic guided wave travels along the

axial length of pipeline with low attenuation. Other NDT testing such as UT, RT, and ET is spot

measurement tool with which the tested area is limited to the probe installation location. Because

the axial symmetric guided wave, torsional mode, fills the pipe cross-sectional area and

propagates though the axial direction, the guided wave testing screens 100 % volume of pipe wall

for cross-sectional area change such as corrosion and erosion. The volumetric inspection of

piping significantly reduces the location for follow-up inspection.

The guided wave propagates through the pipe wall so that the followings are advantages:

1. Long-length of pipeline can be inspected giving comprehensive condition information in a

short time.

2. Inaccessible locations can be inspected: soil-air interface, concrete-air interface (if the

concrete is not bonded to the pipe), wall penetration, buried pipeline, road crossing

pipeline, etc.

3. Long length of pipeline can be screened with several access locations for installing the

guided wave probe and for follow-up testing if indication is found. It significantly reduces

preparation time and labour for installing scaffold of high-elevation pipeline, removing

insulation of insulated pipeline, and excavating buried pipeline.

4. The high temperature (up to 500 °C) pipeline can be inspected or monitored during

normal operation without removing heat tracer lines.

The weld in pipeline plays important roles in long-range guided wave testing. It is big reflector

ranging from 10 to 30 percent depending on operating frequency, and weld bead height relative to

wall thickness. It is a reference estimating defect size in cross-sectional area and a reference for

phase checking of signal. For a good condition of pipeline, the phase is used for differentiating

defect from geometric features. The weld is also used for determining inspection range of guided

wave testing. Because the weld is a big reflector, we can calculate the inspection range with the

signal-to-noise ratio of weld signal. The weld signal is especially useful for inspecting buried

pipeline for measuring inspection range and estimating defect size.


The most difficult question to answer in guided wave is the inspection range. How far can your

system inspect? It depends on capability of guided wave system (how strongly generates torsional or

longitudinal mode and how much reduce the generation of flexural modes), defect size, and attenuation

(operating frequency, geometric features of pipe, corrosion condition, pipe coating, insulation, depth of

burial, and the nature and degree of compaction of the surrounding soil).

The inspection range and defect sensitivity depends on the probe including guided wave system,

operating frequency, and attenuation due to geometric feature or insulation. With strong generation of axial

symmetric mode, MsS GWT system can detect 2 to 3 % defects located at about 150 meter after passing 18

girth welds in a 16-inch OD aboveground straight gas transmission pipeline [Pipeline and Gas Technology,

August (2006), pp 28-31].

The attenuation is higher with increasing wave frequency and soil depth. Coating and

insulation also increases the wave attenuation to be higher than in bare or painted pipe. The below

data were plotted to show the soil effect of wave propagation. The top plot shows the data of 20-

kHz torsional mode from 4.5-inch-OD bitumen coated pipe without soil cover. The bottom was

acquired after 3.2-ft soil cover. The attenuation was significantly increased due to guided-wave

energy leakage to soil.


The following shows the photo and data of MsS guided wave tested for 16-inch OD

aboveground straight gas transmission pipeline. The guided wave can detects about 2.5- percent

cross-sectional area defect (marked with couplet in the bottom graph) located at about 493 ft after

passing 18 girth welds. Please see that MsS data have high spatial resolution compared to other

guided wave systems. With the below inspection we can inspect over 500 ft length of piping in one

direction for detection of 2 to 3 % defects on straight bare or painted lines.


The guided wave system using MsS probe has much merit compared to those using discrete

piezoelectric transducer belts. The following is the list to check before purchasing guided wave system.

The data in the parentheses are specifications of MsS system.

1. Operating frequency [5 kHz to 250 kHz]

2. Price of the system is reasonable compared to other guided wave systems.

3. Additional maintenance cost is very low compared to other guided wave systems.

4. Defect detection sensitivity [Sensitivity is very high with sector probe and high-frequency

operation]

5. Sum of dead zone length and near field length [It is 4 inch with 128 kHz]

6. Inspection range [about 500 ft along one direction for aboveground painted pipeline for finding 2 or

3 percent cross-sectional area defect]

7. Weight of equipment [about 12.5 kg]

8. Weight of probe [0.8 kg for 24-inch pipe probe; we don’t use crane to lift the guided wave probe]

9. High signal-to-noise ratio [Less flexural mode generation than any other guided wave systems]

10. Broad band operation [We can test 5 to 250 kHz with one strip installation]

11. High spatial resolution by using high frequency and low number of cycles [We use 1 or 2 cycles for

GWT]

12. Finding defect around the pipe circumference [we use sector probe]

13. Inspection locations per day [We can usually inspect 5 to 30 locations per day depending on pipe

size and accessibility]

14. Signal repeatability [MsS system generates high-repeatable data for guided wave monitoring with

360-degree covering probe.]

15. High temperature application [MsS probe can inspect up to 500 C using mechanical coupling tool]

16. Size of probe [MsS probe is very thin and thus can be installed on the pipe having about 0.4-inch

gap between pipes.]

17. Training [The MsS technique is trained by Level III in GWT who is also ASNT NDT Level III in

UT and ET and has more than 13 years experience in GWT with 13 US patents about guided wave

application]

18. Continuous support and responsibility [We support clients with continuous training]

19. Honesty [We are honest to client. We support client based on our experience of inspection service,

research, development, training, data analysis service, guided wave software development, and

consulting.]

20. Other application area [MsS system can be used for plate, buried rod, cable, boiler tube, condenser

tube, heat exchanger tube, tube angle, and angle beam.


The high-frequency operation of MsS guided-wave system includes much merit compared to GUL and Teletestsystems in piping inspection and monitoring. MsS system operates at wide frequency range of 5 kHz to 250 kHzwith pure torsional wave mode. The high-frequency operation allows finding smaller defects in short (less than 30ft along one direction) distance for insulated pipeline in refinery, chemical and petrochemical facilities. It also hasless interaction with attached geometric features such as clamp and pipe support exampled in the below.

Example 1: Clamp on pipe

The following figure shows inspection report plot in dike penetration region (top graph), photo of a clamp (leftbottom), and amplified plot of clamp signal (right bottom). The inspection report was made with 64- and 150-kHztorsional mode data. The clamp signal at about 2 m was shown with 64-kHz data. The video signal in the dottedline was plotted at the right bottom with rf signals. The clamp signal is strong at 32 kHz data, and it decreases asthe frequency increases as shown in the amplified plot. The clamp signal at 150 kHz is not shown because theguided wave signal at high frequency has less interaction with the clamp. If there is no defect in pipe clamp, nosignal is reflected from it. Therefore, 150-kHz signal can indicate a defect under the clamp if the reflection fromthe clamp is strong at 150-kHz data. The following field testing shows that the inspection range at 150 kHz islonger than that at 32 and 64 kHz if the pipeline includes tightened U-clamps. If the inspection was performed atonly low frequency, the trailing signals of clamp makes a false call or makes difficult to find defect at the clamp orbehind it.


Example 2: Unwelded pipe support

The following figure shows inspection report plot (top graph), a photo of pipe support (the left bottom), and

amplified plot of pipe support signal (the right bottom). The big pipe was supported by a small diameter pipe on

concrete block. The signal from a pipe support is shown at 32 and 64 kHz. But the pipe support signal at 128 kHz

does not show because the guided wave signal at high frequency has less interaction with an attachment. If there is

no defect in pipe support, no signal is reflected from it. Therefore, 128-kHz signal is much easier than low-

frequency signal in finding defect in pipe support.


Example 3: Welded pipe support

The following figure shows inspection report plot (top graph), photo of welded pipe support in the insulation(left bottom), and amplified plot of pipe support signal (right bottom). The inspection report was made with 128-kHz torsional mode data. The welded pipe support has strong interaction with low-frequency guided wave asshown in the amplified plot of pipe support signal (right bottom). The amplified plot was marked with red-dottedline in the inspection report plot. The 32-kHz torsional data shows the strong trailing signal following the pipe sup-port signal. If this inspection was performed at less than 60 kHz, the big trailing signal at low frequency causes afalse call. Therefore, high-frequency inspection of pipeline is necessary for testing a pipeline having welded pipesupport.

The trailing signal is strong if the circumferential length is less than about 5 times of operating wavelength. Be-cause 128-kHz torsional mode has 4 times shorter wavelength than that of 32 kHz, 128-kHz torsional mode doesnot interact with the pipe support and its signal is much better in finding any defect at the region following a pipesupport.


Example 4: Pitting Corrosion under Insulation

The following photo shows CUI (corrosion under insulation) guided wave testing. The MsS probe

was installed after removing the insulation and tested at 32, 64, and 128 kHz. But the small surface cor-

rosion was sensitive to high frequency of 128 kHz (Wave length is 1 inch). We found pitting corrosion in

the elbow region and verified by client after removing the insulation.


The guided wave testing uses low-frequency ultrasonic wave that is transmitted to the

pipeline. Once the ultrasonic wave is generated in the pipeline, its propagation or interaction

with defect or geometric features does not change if the frequency and wave mode is the

same. Therefore, MsS system can inspect any pipeline that other guided wave systems can

do because we have stronger guided wave generation and wider frequency range than other

systems. The application piping structures are; piping systems in oil, gas, and petrochemical

facilities; offshore piping systems/risers; power generation piping systems; road crossings/

levee penetrations; Elevated or complex piping systems with limited clearance; and buried

pipelines.


Guided wave inspection is performed on fixed inspection intervals prescribed by

governmental regulations that are sometimes not in line with the maintenance requirements. Since

guided wave is a surveying tool, the guided monitoring is required to do in-service testing before

a planned shutdown. Ample time is then available to plan the necessary maintenance work long

before the actual shutdown takes place. Therefore, total downtime for the installation is reduced.

The MsS System has a number of advantages compared to GUL Wavemaker and Teletest

in guided wave monitoring. Since the MsS system is based on the magnetostrictive sensor (MsS),

the benefits of long-range guided wave monitoring with MsS system are:

- MsS probes are much cheaper than piezoelectric ring probes.

- The probe is light (less than 0.5 kg for 24-inch-OD pipe), so that the installation work is

easy at high level.

- Easy to install in structures for monitoring

- No limitation of pipe size exists because the MsS probes are directly made at on site

with material.

- Only a 25-mm clearance is needed around the pipe in permanent monitoring.

- MsS probes work well at high temperature pipe up to 300°C.

In MsS guided wave monitoring, the MsS probe is permanently installed at a corrosion-

sensitive region of structure; baseline data are obtained; the structure is periodically tested; and

the periodic data are compared with the baseline data to identify structural changes with time.

The merits of MsS guided wave monitoring compared to inspection are:

- Quickly obtain new data with the installed probes

- Data is acquired from the same location of probes

- Small changes in condition can be readily detected with comparison of baseline data

and periodically monitored data

- Finds defect initiation and growth in geometric features such as weld, support,

attachment, etc.

- No need to remove insulation or excavate soil for the probe installation except the first time

- Allows in-service testing in high temperature or high elevation line.

- Gives ample time for maintenance works and reduces total downtime


The inspection report of MsS guided wave testing includes four pages— Result table, Analyzed

data plot, Rectified RF and Spectrogram plot. The result table includes basic information of test

location and inspectors, inspection summary, and information of all indications.


The analyzed data plot consists of two sets of video data acquired at two different frequencies or

two different locations, all indications in the result table, DAC curve plot. The data analysis was

performed with DAC-compensated plot in which DAC curve is compensated in the video data.


The third page includes rectified RF and spectrogram data plots acquired at 20-, 32-, 64-, and

128-kHz center frequency. The surface corrosion of pipe can be easily observed in 128-kHz data

with noise-like signal following the initial pulse due to surface scale.


# Training and Certification

The MsS guided-wave inspection training covers the principle of guided waves and theirpropagation in pipeline, guided-wave generation using MsS probe, MsS probe installation, MsSequipment operation, data analysis and reporting. The MsS guided-wave inspection trainingincludes 3 certification levels:

Level I Certification: Requires 5-days’ training course with passing a written and practicalexamination. Level I operators can test pipelines according to written instruction. The Level I cananalyze data with the help of guided-wave inspection report software and report the findings forstraight exposed pipe and above ground insulated pipeline.

Level II Certification: Requires guided-wave testing experience of 9 months or 630 hours in5 to 27 months with passing a written and practical examination. Level II operators can analyzeburied pipeline data, monitoring data and data tested in specialized pipeline with multiplefrequencies. The Level II should understand the guided-wave interaction with defects or geometricfeatures at different frequencies.

Level III Certification: Developers of MsS technology have this qualification.

# Data Analysis

Surveying with guided waves often requires interpretation of complex signals. GWA hasmuch experience in data analysis and report, and uses Matlab software for professional dataanalysis. The data analysis service of GWA has following procedure:

1. A client sends at least 5 sets of data to GWA for making report format and estimatinganalysis time of each data set.

2. GWA sends the client sample reports and the estimate cost of analyzing and reportingdata.

3. The client approves it and sends GWA all data to be analyzed and reported.4. GWA loads all inspection reports in GWA ftp site and client fetch them.

We are professional in guided wave data analysis and clients will be satisfied with our service.

The MsS system is used to inspect and monitor many different kinds of piping systems, andthe general inspection report software sometimes takes more time and effort to analyze for a specialpiping application such as road crossing, storage tank leg, short buried piping, and off-shore piping.GWA will help our client through programming software tailored to our client’s requirement forhandling a special application. Also, the report format in the inspection report software can betailored to our client’s requirement.


# Field Trip

The experts in GWA will make trips into the field for hands-on training and demonstrationsof field techniques. Field trips to inspection sites are helpful to companies starting guided waveservice and GWA helps clients on the preparation of accessories, MsS probe installation, selectionof probe installation location, decision of inspection range, and data analysis and reporting.

# Consultancy

MsS system has many application areas for detecting corrosion or cracks with guided waveinspection and monitoring. Some application requires testing with multi frequencies to get moredefect information, and using more than one pair of probes to achieve longer inspection range inhigh attenuation pipe. GWA helps the client in the following ways:

- Visit client for on-site installation of MsS probes- Analyze and report of inspection and monitoring data- Make guided wave inspection/monitoring procedures for special application- Program a tailored software for special application- Demonstrate the MsS system to clients- Train clients to transfer upgraded MsS technology including probe installation procedure, new

probe, and upgraded software.

MsS technology has many proven and potential application areas when it is properly used.The GWA experts will work with clients to use the MsS technology in their special applications.

If our client’s application cannot be solved with the current state-of-the-art of MsStechnology, GWA will connect you to the development team at SwRI® to solve it through furtherresearch and development.


Guided Wave Analysis LLC

7139 Callaghan Road

San Antonio, TX 78229

United States of America

The MsS system for guided wave inspection, monitoring, and research is commercially available to

inspection service providers, research institutes, and universities. For more information or inquiries

about the MsS system and its accessories, please email [email protected].

Technical support inquiries such as consulting of difficult inspection situations, data analysis,

additional training of new member, or on-site demonstration should be directed to

[email protected]

For information about renting MsS system, please email to [email protected].

For inspection service inquiries with MsS System, please email [email protected].

Person to ContactSang Y. Kim, Ph.D.MsS Guided Wave Testing Level IIIASNT NDT Level III in ET and UTPhone: 210-842-7635Email: [email protected]

Magnetostrictive Sensor(MsS) System · Magnetostrictive Sensor(MsS) System For Guided Wave Testing...

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