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1. Technical background onguided wave testing (GWT)

2. Mss Equipment and software

operation for GWT3. T-wave pipe testing/inspection

and calibration procedures

4. Data analysis and reportingsoftware operation for level I

5. Other MsS Guided waveapplications and pipelinemonitoring

MsS Training Subject

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Purpose

This procedure constitutes the written practicefor the qualification and certification ofnondestructive examination (NDE) personnal in

accordance with the guidelines of SNT-TC-1A foruse of magnetostrictively generated ultrasonicguided waves for inspection of pipe

This procedure applies to the following NDE

methodsMethod Abbrivation

Magnetostrictive sensor MsS

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Definitions

Certification: Written and practical testimony of qualification

Experience: work activities accomplished in MsS under

direction of qualified supervision including performing the

MsS method and related activities

Qualification: demonstrated skill, training, knowledge, and

experience required for personnel to properly perform the

duties of a specific job.

Training: the program developed to impart the knowledge

and skills necessary for qualification

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APPLICABLE DOCUMENTS

Personnel qualification and certification in

nondestructive Testing American society for

Nondestructive Testing (ASNT)

Recommended practice No. SNT-TC-1A,

1975,1980, 1984, 1992 Editions.

These documents are used as a guide for the

MsS certification to be through ASNT

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RESPONSIBILITY

The director of the department of sensor systems and NDE

Technology (NDE Department) in southwest research institute

shell be responsible for the qualification and certification of

NDE Personnel

A level III individual(s) designated by the director shall be

responsible for the administration of the MsS training

program and for the approval, administration, and grading of

examination.

An MsS instructor shall be responsible

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LEVELS OF MsS QUALIFICATION

MsS Level I Qualification:

A Level I Shall be qualified to perform specific equipment setups,

calibrations and tests, and to record data according to specific

written instructions. The Level I Operator may perform

preliminary evaluation and interpretation of the data for the

purpose of determining the acceptability and quality of data.

The data Acquisition system (DAS) Operator shall be

thoroughly familiar with the scope and limitations of themethod and shall be responsible for on-the job training and

guidance of trainees

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LEVELS OF MsS QUALIFICATION

MsS Level II Qualification:

A Level II Shall be qualified to setup and calibarate equipment and to interpret to

evaluate the results, with respect to applicable codes, standards, and

specifications. The Level II shall be thoroughly familiar with the scope and

limitations of the method for which the individual is qualified and shallexercise assigned responsibility for on the job training of trainees and level I

personnel. The Level II shall be able to prepare written procedures and to

report the results of an examination. In addition to the duties and

responsibilities of the level I operator, the level II shall be qualified and

responsible for interpretation and evaluating results of MsS examinations andreview data with respect to applicable codes, standards, procedures and

specifications. The Level II shall be able to organize and report MsS

Examination

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LEVELS OF MsS QUALIFICATION

MsS Level III Qualification:

A Level III Shall be capable or and responsible for establishing

techniques and procedures: interpretation codes, standards,

specifications and procedures; and designating the particular

examination method, technique and procedure to be used. An

MsS Level III must have a level III MsS Certificate from SWRI.

He shall be capable of interpretation and evaluating results in

terms of existing codes, standards and specifications.

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Physical background on Guided waves: What are guided waves?

Comparision between convnesional UT and Long Range Guidedwave Inspecton.

Guided waves in pipeline

Dispersive characteristics of Guided wave

Selection of Guided wave Modw for Long Range WaveInspection.

Guided wave Systems and probes: Commercial System

Difference of continuous and discrete guidedwave testingprobes

Near Field, Dead Zone, Operating Frequencies.

Contents:

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Background on Long Range Guided

wave Inspeciton.

Introduced for field use in late 1990.

Guided-wave Probe used.

Piezoelectric based- Teletest and Wavemaker

Electromagnetic based MsS System

Guided-wave used. Mode Torsional and Longitudinal

Frequency Typically 10 to 250-kHz.

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Comparisons

Conventional GWT (or LRUT)

Usage Local Spot inspection Rapid surveying of large

areas

Waves Used Bulk Waves

(compressional, shear)

Guided waves

Frequency Range 0.5 to 10MHz Under 250 kHz

Defect Detection Small defects Relatively Large defects

Inspection Range Inches On the order of 1 to 500feet.

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Nature of Guided waves

Guided waves exist in many different forms

Longitudinal, torsional, flexural in pipe

Lamb wave, shear-horizontal wave in plate

Their properties (Velocity, displacement pattern)vary significantly with the geometric shape

and size of the structure and wave velocity

In contrast, bulk waves used in conventional UT depend onlyon the structures material.

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Comparison of Inspection Range

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GWT is Volumetric Inspection

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Prominent Features of Guided-Wave Technology

Rapidly provides comprehensive condition information on

large areas of structure.

Requires minimal preparation

Insulation removal, scaffolding, excavation, coating removal,

etc.

Inspection inaccessible areas remotely

Pinpoints where to use quantitative follow-Up

Reduces inspection cost and enhances over all inspection efficiency

100% of Volume is inspected.

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Particle Displacement in a Pipe

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Guided Wace Modes in Pipeline

Wave Mode wave propagation direction ParticleDisplacement

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Axial Symmetric Modes

Wave Mode wave propagation direction Cross-sectionalView

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Dispersion Curve of 4.5-inch-OD, 0.007 inch-wall

Steel Pipe

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Comparison of Two Modes in 4.5 OD,

0.337 wall steel pipe

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Tone B rst Signal

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Tone Burst Signal

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Effect of Wave Dispersion

Dispersion wave mode- It is wave Packet broadens as thewave Propagate

Time

Amplitude

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Purpose of GWT

Finding defects in pipelinewith highsignaltoNoiseratio (S/N) and with high

spatial resolution (SR)

UT uses tone burst electronicpulse having low-number

of cycles for highspatialresolution (SR)

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Selected Wave Mode of GWT

T (0,1) Torsion Mode

in Pipeline

SH0, Shear horizontal

mode in plate.

Shear Wave mode in

bulk material

These three wave modes are non-despersive and has the same velocity

Di i C f 4 5 i h OD 0 007 i h ll

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Dispersion Curve of 4.5-inch-OD, 0.007 inch-wall

Steel Pipe

Guided wave testing uses T(0,1) mode- Torsional mode or L(0,2) mode at non-

dispersive frequency region.

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Selected Wave Mode of GWT

T(0,1) mode is better than L(0,2) mode-

Not Effected By Liquid Contents in the Pipe

Shot Wavelength at the Same Frequency (i.e High Sensitivity)

No Dispersion at any frequency RangeCan find Axially Oriented Defects

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Selection Criteria for Guided-Wave Mode and

Frequency for Long-Range Inspection

Minimal wave Dispersion

Range of Inspection

Defect Size

Ease of mode control

Minimal complication from other wace modes

Best modes-T(0,1) in pipe

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Commercial Guided Wave Systems

Magnetostructive Technology Is developed at South west Research institute

(www.swri.org)

Is trained and advertised by Guided Wave Analysis LLC

(www.gwanalysis.com)

Piezoelectric Array Technology Is developed at imperial College

Is lincensed to 2 cmompanies

Plant Integrity Ltd (www.plantinegrigy.co.uk) ownedsubsidary of TWI

Guided Ultrasonic Ltd (www.guided-ultrasonics.com)

http://www.swri.org/http://www.gwanalysis.com/http://www.plantinegrigy.co.uk/http://www.guided-ultrasonics.com/http://www.guided-ultrasonics.com/http://www.guided-ultrasonics.com/http://www.guided-ultrasonics.com/http://www.plantinegrigy.co.uk/http://www.gwanalysis.com/http://www.swri.org/

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Same Characteristics of Guided wave Systems

The Same Characteristics

100 % of pipe is inspected

Battery operation of main system

Using torsional and longitudinal mode

Data analysis software

Wave propagation characteristics

Interaction with defects of guided wave

Attenuation at insulation, soil, and high viscous material

No inspection across flanges Non detection of small, isolated defects (Pin-hole type) at long

distances

Defect detection threshold increment after passing elbow.

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Magnetostrictive sensor (MsS) System

for Generating Guided wave

MsS probes

MsSR3030R

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Magnetostrictive sensor (MsS) System

for Generating Guided wave

MsS probes

2-inch-wide

FeCo strip

FeCo Strip attached to the Pipe

by using Shear Couplet

Ribbon Coils Placed over the strip

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Comparison of Guided wave probes

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Demerit of Using Discrete Probes

(Non Axial Symmetric probes)

Generation of Flexural Modes

Existence of Near Field Zone (4 or 5ft)

Easy Flexural Mode generation due to sludge,

internal corrosion, bad contact, tilt or

unbalanced probe.

Poor direction control or bad cancellation

Only operating low frequency guided wave

(usually less than 50kHz)

i l d l i l d

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Torsional and Flexurial Mode

Generation

C i b C i d

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Comparison between Continuous and

discrete probes.

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Flexural Mode Generation

Is due to non balance between probes caused

by Probe itself

Localized corrrosion Bad contact, tilt

Localized corrosion on surface or inside of pipe.

Probe insulation location needs to be locatedat no Sludge or internal Corrosion.

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Poor Direction Control

N N Fil d L th f M SR 3030R

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No- Near Filed Length of MsSR 3030R

System

Near field length

Is defined as the length from the probe to the

position at which the axial symmetric guided wave

covers the whole circumference of pipe withalmost the same signal amplitude.

MsS System

Has no near filed length (0 ft) because the probecovers 360 degree of pipe circumference.

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Short Dear Zone Length of MsS Sysem

Dead Zone Length

Is generated as a result of electric interference

during the high-pulse electric signal transmission

to the probe inside the equipment.

Dead Zone Length of MsS System

Is about 4inches at 128-kHz center frequency

Is 7 inches at 64-kHz center frequency Is about 11 inches at 32-kHz center frequency.

Wh th di t b t

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Why the discrete probe can not

operate at high frequency ?

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MsS Probe

2-inch-wide

FeCo strip

Operate at 16 kHz also.

Operate at 16-, 32-, 45-, 64-, 90-,

128-, 180-, 250-kHz center frequency

2-inch-wide

Ribbon cable

32 kHz

2-inch-wide

FeCo strip

128 kHz

64 kHz

Frequency Adapters

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Interaction of Guided wave with defect

Guided Wave V= f

Where V- Velocity, f- Frequency and- Wave Length

Frequencies: 250kHz 128kHz 64kHz 32kHz 16kHz

Wavelength: 0.5inch 1inch 2inch 4inch 8inch

Defects in pipe Well

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MsS Guided wave system

MsS Probe Is based on magnetostrictive effects

Uses 2-inch-wide ferromagnetic strip (FeCo) and ribbon cable orelectric cables or electric wires

Covers 360 degrees of pipe circumferece.

MsS System Has short dead zone length

Has no near field zone length

Has good direction control

Generates less flexural modes (coherent noise) Operates at high frequency higher than 100kHz.

Operates at wide frequency range (16kHz to 250kHz)

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Summary

The guided wave testing (GWT) Is a method using low-frequency ultrasonic wave for a long

distance

Rapidly provides comprehensive condition information on largeareas of structure (Screening tool)

Has three curve for checking wave modes form studying Uses torsional mode that is non-dispersive.

Can generate using magnetostructive sensor (MsS) or a belt ofpiezoelectric transducers

Uses direction control fro inspection and monitoring.

Needs to know dead zone length and near field length Operates at frequencies 16kHz to 250kHz

Needs to operate wide frequency range for finding differentsizes of defect.

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Why is Torsional Mode Used?

Free From dispersion-related problem-up to the cutofffrequency of T(0,2)

Wave Properties independent of Pipe size-up to Fc

Not Affected by Liquid in the pipe

Less prone to generate Flexural (extraneous) waveModes

Easier and simpler to use than longitudinal modeoperation

Economical for permanent installation for long termmonitoring

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Generation of T(0,2) Mode

Free from dispersion-related problem-up to thecutoff frequency of T(0,2)

If d=/2, the T(0,2) mode is firstly generated Fc=V/ C= V/2d, where d is the wall thickness

For example, 1-inch-thick wall Fc=64kHz

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Non-Dispersive up to Cut-Off Frequency

MsS Torsional Mode Generation and

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detection

Uses thin magnetostrictive strips placed around

pipe and MsS Coils placed over the strips

Strips are either shear-coupled, bonded, or

mechanically coupled to the pipe Residual magnetization is indiced in the strips

(called Magnetic Conditioning)

T-Mode is generated/detected in the stripsthrough Magnetostrictive effects (called

Wiedmann effects)

MsS Probe For T-Mode piping

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p p gInspection

MsS probes

Magnetostrictive Strip Ribbon Coils Placed over the strip

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MsS Principle

Generation- Based on the Magnetostrictive (orJoule, 1847) Effect.

Detection-Based on the Inverse Magnetostrictive

(or Villari, 1865) effect and Magnetic Induction(Farady, 1831)

To Operate MsS, Both DC bias magnetic fields andAC Fields are needed

Relative orientation between the DC and AC fieldsdetermines the type of wave modegenerated/detected.

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MsS L-Mode Generation

HB DC Bias Magnetic Field

HAC AC Applied Magnetic field

HT= HB+HAC +Z

L=WaveHT=HB-HAC - Z

Total Field Strain

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Torsional Mode Generation

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Physical Properties of Strip Materials

FeCo (Heat Treated) Nickel (Annealed)

Saturation

Magnetostriction

60X10-6 35X 10-6

Curie Temparature 17200F, 9380C 6620F, 3500C

Yield Strength 73kSi 15kSi

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Advantages of Iron-Cobalt Strips

Produce stronger signals- about 4 times larger

than signals obtained with nickel

Can be uses for high-temperature applications

Mechanically stronger and, thus, can tolerate

mechanical stresses

Disadvantages- more expansive; less available

commercially

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Properties of FeCo Strips and handling

Requires a sepecial Heat Treatment (HT)

May show discolored areas from HT

Discoloration does not degrade sensor performance

Mechanically strong, but some what brittle

To avoid the irregular cut

Use a good metal shearing tool

Gut in its natural curved shape Do not put the strip in stressed state by straightening it for

cutting.

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Direction control of Guided wave

Achieved by employing twosensors and phased arrayprinciple

A -wavelength separation isused for both sensor placementand MsS transmitter / Receiver

operation.

Nominal T Mode Wavelength in steel pipe

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Nominal T-Mode Wavelength in steel pipe

(V-3260 m/sec)

Frequency (kHz) Wavelength (inch) Quarter Wavelength

(inch)

250 0.51 0.13

128 1.00 0.25

64 2.00 0.50

40 3.20 0.51

32 4.00 1.00

20 6.40 1.60

16 8.00 2.00

10 12.80 3.20

8 16.00 4.00

Direction Control Simulation

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Standard sizes of Ribbon Coil and

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Standard sizes of Ribbon Coil and

Magnetostrictive Strip

Ribbon Coils

Width-2inch

No. of Conductors-40

Magnetostrictive Strips

Width-2inch

Thickness-0.004inch for Iron Cobalt

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Coil Adapters

Designed to turn parallel conductors in ribbon

into an encircling coil

Standard type

Dual Probe 32, 45, 64, 90, 128, 180, and 250 kHz

operation

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Standard MsS Probes

2-inch-wide

Ribbon cable

32 kHz

2-inch-wide

FeCo strip

128 kHz

64 kHz

Probe Installation methods

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Probe Installation methods

Mechanical Dry Coupling

Requires good pipe surface

High temperature application up to about 500 Celsius degree

Shear Couplant

Top of Paint without removing it Relatively smooth surface

Many testing locations per day

Epoxy bonding

Rough Pipe surface or permanent monitoring

High Temparature (up to 200 0C)

Many Testing Locations per day

New Mechanical Coupling Tool

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p g

Mechanical coupling Ribbon Cable

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Strip Preparations

For Pipe 16 inches in OD or smaller, cut the

strips to a length that is slightly less (about

0.25 inch or so) than the pipe circumference.

For Pipes Larger than 16inches in OD, dividethe total required strip length in to 2 ro

segments

Segmented strips make handling and alignmenteasier during the bonding process.

Making Handles for Holding Strip During Epoxy

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Bonding

Cut 2-Wide making type of

about 4 length

Fold the 2-wide masking tapeat nearthe center and attach

itself of 1 length

Attach the both ends ofmasking tape to the strip near

the end

Repeat the above procedureto the other end.

Surface Preparation

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Surface Preparation

Wipe any dirt or loosecorrosion with paper towel

If the surface is rough, use awire brush or sand paper

Paint is okay, if the pantedsurface is smooth

If the paint has blisters or isdetached from the pipe

surface, remove the paintand clean the area.

Reference Line Drawing

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Reference Line Drawing

Place a Wrap-A-Round alongthe pipe circumference andalign it properly

Draw a line along one edge ofthe Wrap-A-Round

Reference Line is necessary to align strips properly

during the bonding process

Install Strip around pipe using shear couplent

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Install Strip around pipe using shear couplent

or Epoxy

Attach 2 widemasking tape onboth sides of strip

Feco Strip

Masking Tape

Pipe

Epoxy Shear Couplant

Ms S Data Comparison

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Ms S Data Comparison(64 kHz Data from 16 OD Pipeline sample at ambient Temp)

M S T t P d

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MsS Test Procedures

Prepare Strips

Bond Strips around Pipe

Magnetize Strips for T-Mode Operation

Place MsS Coil over the strips

Connect MsS to instrument

Acquire Data

Strip Preparation and Bonding

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Strip Preparation and Bonding

Step 1: Cut the strips to right length

Step 2: Make Handles for holding strip during epoxybonding

Step 3: Clean the pipe surface and draw reference linearound the pipe

Step 4: Mix the epoxy and apply it to the strips

Step 5: Bond the strips around the pipe following thereference line and the keep them place bywrapping over the strips with a rubber band untilepoxy cures

P i E S T b

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Preparing Epoxy Squeeze Tube

Install the epoxy in theepoxy squeezer and

attach the nozzle in

front of epoxy tube asshown below.

Mixing and Applying Epoxy

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Mixing and Applying Epoxy Mix/Prepare the adhesive and apply to the contact side of

strips

5-Minite epoxy is only okay for bonding strip in a pipe of 8-

inch or smaller OD

For 10 or larger pipe, use an epoxy having 20 or longer curing

time

Bonding Procedures(f Pi ith 16 OD l )

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(for Pipes with 16 OD or less)

Place and bond the stripsaround the pipe and press them

onto the pipe

While slightly wiggling and

rotating the strips and

squeezing out excess adhesive,

adjust the alignment of strips.

Use masking Tape for Positioning

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g p g

attached strip

Attach 2 widemasking tape on

both sides of

strip

Feco Strip

Masking Tape

Pipe

Bond Procedures for Segmented strips

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(for Large Size pipes)

Mix/prepare the adhesive and apply to the contact side of thestrips

Bond the Strip segment on the pipe and adjust its position so that

one edge of the strips is aligned along the reference lines; whenproperly aligned, keep the segment in place by taping it down at

both ends and a few other locations along its length

Repeat the process using the remaining strip segments

Use Adhesive whose working time is longer than the time needed

to complete the bonding process of all strip segments around the

pipe.

B di P d (C td)

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Bonding Procedure (Contd)

Wrap a rubber strap overthe strips and keep strips

pressed down during

adhesive curing

After the adhesive is

cured, remove the rubber

strap.

Strip Conditioning procedures afterb di i

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bonding on pipe

Place conditioner over strips andmove it around the pipe 2 or 3

times relatively constant speed

abut 1-2 ft/sec); then remove is

from pipe in a continuous motion

Any halt in motion may result in

non uniform conditioning and

degraded MsS Performance.

Ribbon Cable information

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Ribbon Cable information

Place Ribbon calbe on topof attached FeCo Strip

This is one of most

important procedure

Many inspectors fail

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Reflection of Guided waves

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Reflection of Guided waves

Anomaly in pipelines includes corrosion, crack or weld etc..

When guided waves hits a change in cross-sectional area, they reflects

back to word the MsS Probe.

Signal amplitude is proportional to Cross-sectional area of defect

What Determines GWT Signal?

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g

Sr= rSi (ignoring attenuation)

Sr-Detected signal amplitude r- Reflection coefficient of reflector

Si- Transmitted signal amplitude

r-Reflection coefficient; dependant on wave frequency,reflector size (depth, circumferential extent and axial length)and shape

Phase-Dependent on reflector type (weld, defect)

To be meaningful, signal amplitude is converted from voltageto reflection (%)

Attenuation correction

Calibration

Reflection Coefficient (r)

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Reflection Coefficient (r)

Impedance (Z) of Guided waveAVA-Cross Sectional Area

- Density

VVelocity

Reflection Coefficient (r) Calculation

r= Reflection Coefficient

Z1= Impedance of region 1

Z2= impedance of Region 2

Approximate Defect Sizing

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Approximate Defect Sizing

Approximating Defect Sizing

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Approximating Defect Sizing

Approximation of defect sizingDefect size is proportional to reflected signal amplitude

r- Reflection Coefficient Ap Crossection area of the pipe

Ad Cross sectional area of pipe at defect location

Adefect Cross Sectional area of defect

Sr= rSi Y-Axis amplitude should be displayed with reflection coefficient (%reflection)

Y Axis plot of Guided wave data

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The inspection range and threshold sensitivity are setby the signal-to-noise (S/N) ratio in guided wavetesting. Signal to noise ratio (SNR) should be minimum 2 or 1 SNR

for detection

The reflection coefficient or Percent reflection isproportional to signal amplitude.

The reflectivity or reflectance is proportional to thepower of energy.

If a signal has 3 SNR ratio (0.3 volt for signal, 0.1 volt for

noise), its reflectance is 9. If the data are plotted with signal amplitude or reflection

coefficient, its amplitude is propotional to the defect cross-sectional area of pipe.

% Reflection and % CSA

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% Reflection and % CSA

r is the reflection coefficient

% Reflection and %CSA

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% Reflection and %CSA

Reflection of Guided wave in pipe

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Reflection of Guided wave in pipe

Acoustic impedance of Guided wave in pipe

Z = V1A

:Density of Pipe A- Cross sectional Area of pipe

V1: Velocity of the guided wave

Reflection of Guided wave

Zp : Acoustic Impedance at the pipe location with andwithout defects

Zdm : input impedance of the defect

Transmission line Model

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Recursion relation for input impedance of two successive

layers

K Wave Number Thickness of the layer

Defect Matching of a NotchTypedefect for Defect Simulation

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defect for Defect Simulation

Pipe Sample Defect and Guided Wave

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Pipe Sample Defect and Guided Wave

Pipe Sample: New Above Ground Pipeline4.5 inch outer diameter

0.337- inch- thick wall

Defects: 2 Inch width

0.23- inch depth (deepest)

2-to 4- inch length with 0.25 inch step

7.17 percent maximum cross sectional area defect

Guided wave: 64 kHz, 2- Cycle L(0,2) mode wave

Guided wave was directly generated in pipe without anycoupling medium.

Comparison of Experimental andsimulated signals

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simulated signals

Examples of Experimental andsimulated signals

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simulated signals

Calibration methods

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Method 1 Indirect calibration based on geometric signals in

the data (such as end or weld signals) Typical R Value assigned 95 to 100% for pipe end and 10 to 25% for

weld.

Calibration based on weld signal is subject to significant error

Method 2- Indirect calibration- based on the signals from a

reference reflector (hose Clamp)

R is the reference reflector is determined separately

Fairly accurate on small size pipes

Method 3 Direct Calibration

The transmitted signals is measured and used for calibration mostreliable.

Reflection coefficient of Hose Clamp

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Reference

Direct Calibration Procedures

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Attach a short (2) FeCo Strip

along circumference direction

using double-sided tape

Magnetically Condition the strip

Place a short (1) MsS plate-probe on the strip.

Operating in the pitch-catch mode

and using the plate-probe as the

receiver with no direction control,detect the transmitted signal.

Calibrate using the transmitted

signal amplitude as the reference

Wave Reflection from step-Wise wallthickness change in pipe

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thickness change in pipe

Phase-Checking for automatic identification of

fl

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Reflector Type

Phase Relationship (to Incoming Wave) In phase when reflected from a weld

Out of phase when reflected from a defect

MsS data analysis and reporting software usesphase-checking for automatic reflector identification

Welds, attachments Positive (+) Phase

Defects, Pipe Ends Negative (-) phase

Patent Pending

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Presentation Outline

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Structure Program

Pipe Information

Data Acquisition

Different Data Display

Analysis & Report

Select Data

Select Frequency

Calibrate Distance

Calibrate Amplitude Review & Correct findings

Finish Report

MsS Data Acquisition, Analysis and Reporting

software for Pipeline Inspection

Inspection Report

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Answering Where is a defect?

Velocity and calibration

How Big is it

YAxis scale of report

TCG and DAC plot

Threshold Level

MsS Data Acquisition and Reporting

S f f i li i i

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Software for pipeline inspection

Is a complete tool for acquiring data, analyzing data

and generating inspection reports.

Is Composed of Three sections

Pipe information

Data Acquisition

Analysis and Report

Pipe Information

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Cut- off frequency

Weld reflection

Inspection location

information

Inspector information

Pipelines information

Pipeline note

=> Recording of Basic

information.

Pipe Information in Report

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Pipe Information in Report

Data AcquisitionCut-Off Frequency Directory and keyword of filename

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Operating Frequencyy y

Data Reviewing

Data Display

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Analysis and Report

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y p

1. Select Data

2. Select Frequency

3. Calibrate Distance

4. Calibrate Amplitude

5. Review and Correct Findings

6. Finish Report

1. Select Data

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2. Select Frequency

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3. Calibrate distance

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Answering: where is the defect?

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Look at X- axis Scale and signal width for spatial resolution

Velocity of Guided wave

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Estimation with experience

Calculation with Dispersion curve

Approximate Value

Dependence on elastic constants and density of

material Calculation using signal form known geometric

Features (e.g. Weld)

Accurate

Calculation performed by system software

4. Calibrate Amplitude

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Attenuation of Guided Wave

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Attenuation Varies depending on LocalCondition

Degree of Corrosion

Surrounding environment (buried, insulated, coated,etc.)

Average attenuation is used for Data Analysis

Signals from welds are used for this purpose

Attenuation Correction data

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DAC Curve

Plot

TCG Data Plot

Y-Scale of Guided wave Data

The inspection range and threshold sensitivity are set by the

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The inspection range and threshold sensitivity are set by thesignal to Noise (SNR) ratio in Guided Wave Testing

The Reflection coefficient or percent reflection isproportional to detect cross-sectional area of pipe.

The Reflectivity or Reflectance is proportional to the

power or energy

If a signal has 2 SNR Ratio (0.02 volt for signal, and 0.01 volts fornoise)

SNR of reflection coefficient = 2

SNR of Reflectance = 4

Sr = r Si ==> Y-Axis is Amplitude should be displayed withreflectance coefficient (% Reflection)

TCG Data Plot and DAC Curve

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DAC

TCG

Show what we found

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Threshold level of GWT

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Threshold Level is set to Minimum detectable defect

Signal-to-Noise(SNR) Should be the minimum 2 to 1

for Detection.

Threshold Level should be varied according to

distance

Defect size with 5% Cross Sectional Area (CSA)

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Conclusion on threshold Level

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Look at Y-Scale of data plot

Lowe the threshold level (5% to 0.5 to 1%)

Know that 5% CSA is not the same as 5% wall loss

Set threshold level depending on the distance and pipe size

Check the threshold level depending on the pipe outer

diameter

5. Review & Correct Findings

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6. Finish Report

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Contents of MsS Field test

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Examples of pipeline, inspection, and monitoring

Inspection and monitoring procedure and cautions

Capabilities and limitations of the MsS Technology for

Long Range Piping Inspection and monitoring.

Effects of Geometric features in Guided wave

Effects of contents, coatings, and general corrosion

Inspection and monitoring range

Defect size of GWT

Examples of Pipe Inspection Applications

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Piping Systems in oil, gas, and petrochemical facilities

Off shore piping system/ risers

Power generation piping systems

Pipelines at road crossings/leeve penetrations

Pipeline inspection Examples of Road Crossing

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MsS Pipeline Inspection

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Pipeline MsS Testing

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Bridge Crossing Pipeline Inspection

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Long-Term Monitoring using MsSTechnology

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gy

Long-Term Monitoring of High temperaturePipeline

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Monitoring of Buries Gas Transmission Lines

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MsS Guided Wave Monitoring of Pipelinein a Tunnel

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Poor Epoxy Bonding Epoxy is not completed hardened

=> Epoxy need to be mixed through

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using too small epoxy to fill gaps between strip and pipe surface

=> Use enough Epoxy Epoxy is hardened before finishing bonding

=> use epoxy having a longer setting time

Epoxy is not mixed at a cold Temperature

=> Find an epoxy that is not viscous at a cold temperature

(about

0

Celcius degree) Strip is not attached against the pipe

=> Use Rubber band to hold the strip during epoxy curing

Poor Strip Conditioning

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Too Fast or too slow movement

of Magnets => Move Magnetwith a speed of about 1-2 ft/sec

Go Stop Movement of Magnetic

cart

Stop before removing magnet

=> Remove Magnet in a moving

Principle of Magnetic Motors

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Moving magnet magnetizes the ferromagnetic strip behind it alongthe same direction. The highest density is behind the movingMagnet.

Moving with constant speed along the circumference of pipe makesmagnetization be uniform

Example of Good and poor Condition data

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Poor Amplitude level selection I d f th M S t t l th AC ti fil d

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In order for the MsS to operate properly, the AC magnetic filed

(HAC

) must be smaller than the bias field (HB) applied in the

circumferential direction.

Demagnetization of circumferential magnetization

Signal-to-Noise ratio gets worse

Generate Extraneous mode signal

Transmitter Amplitude Level

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For 8 or smaller pipe and low frequency operation (32-kHz or lower) ,set the transmitter amplitude to 25%level

For 8 to 16 pipe and low frequency operation (32-kHzor lower) ,set the transmitter amplitude to 50% level

For 16 and bigger diameter pipe and low frequency

operation (32-kHz or lower) ,set the transmitteramplitude to 100% level

Suggestions of instrument settings in

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data acquisitions

Use TCG function for acquiring data, especially for long range

inspection

Dont cut data that have higher amplitude than the maximum or

minimum scale of Y-Axis

Reduce pulsereputation rate for short and low attenuation pipe

The sampling rage needs to be at least 10 times bigger than the

operating frequency

Suggestions of MsS Probe installation

in pipeline

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p p

It is recommended to install the MsS Probe at least 3ft apart from a big geometric features

Dont install MsS Probes in the middle of 2geometric features

Dont install MsS Probe in the tapered section

Guided wave cannot inspect after passing two 90-degree elbows

Procedure for finding MsS probe

installation Location in field

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installation Location in field Find a big Geometric feature such as flange, valve, T-Joint, and elbow

Weld

Install MsS Probe at fare as possible from Flange or Valve because they

are completely block the wave Propagation

Install MsS probe at close as possible from the target inspection region

Install MsS Probe at good surface area along circumference of the pipe

If pipe has generalized corrosion with many dents, fill in the dent area

with epoxy before attaching ferromagnetic strip

Finding MsS Probe installation

Location in Field

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Capabilities and limitations of the present MsS

Technology for Long Range Piping Inspection

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Technology for Long Range Piping Inspection

Capabilities and limitations of the present MsS Technology for

Long Range Piping Inspection

Effects of Pipeline Geometric Features and other Conditions

on Inspection capabilities

General Capabilities

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Good for detecting and locating defects such as corrosion metal loss

areas, circumferential cracks, and deep (over 70% wall) axial cracks

Can inspect over 500 feet length of piping in one direction for detection

of 2% to 3% defects on straight bare or painted lines (here, % means

defects circumferential cross-sectional area relative to total pipe wall

cross section.

Can roughly estimate defect size; needs more R&D to achieve defect

characterization

Can distinguish between welds and defects

Effects of Pipeline geometric Features andon inspection capabilities

ff

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Features Effects

Flange/Valve Prevents wave propagation forms end point of the inspection range

Tee Causes large disruption, limits inspection range up to that point

Elbow Short radius 900 elbow, causes large disruption in wave propagation,

limits inspection range no farther than elbow region

Long Radius 900 elbow has negligible effect

Bend Has negligible effect if bend radius >3 times of OD

Other wise, bend behaves like elbow

Side Branch Cause a wave reflection and thus produces a signal, no significant

effects on inspection capabilitiesClamp Causes a wave reflection and thus produces a signal, no significant

effects on inspection capabilities with high frequency guided wave

Weld

Attachment

Causes a wave reflection and thus produces a signal if attachment is

large (such as pipe Shoes, can reduce inspection range.

Interaction of Guided wave with defect

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Guided Wave V= f Where V- Velocity, f- Frequency and- Wave Length

Frequencies: 250kHz 128kHz 64kHz 32kHz 16kHz

Wavelength: 0.5inch 1inch 2inch 4inch 8inch

Defects in pipe Well

Interaction of Guided wave with defect

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Guided Wave

V = f

250kHz 128 kHz 64 kHz 32 kHz 16 kHz

V

V

Pipe Wall

Defects

Frequencies

Guided wave inspection for finding generalized corrosion

in an insulated pipeline

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Finding Corrosion defects with high

frequency guided wave

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Finding external pits with GWT

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Merits on High frequency GWT

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High frequency guided wave Is good for inspecting pipeline having pipe support, clamp,

etc with high sensitivity

Has high sensitivity with short wave length for finding

generalized pitting corrosion

GWT with multiple center frequencies (32, 64, 90,

128 kHz)

Allows finding different sizes of defect

Is good for corrosion under insulation (CUI) inspection

Effects of Geometric Features in GWT

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Effects of Pipe SupportExample: Pipe Support having a small pipe on concrete block

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Effects of welded pipe support

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Effects of Clamp on Pipe

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Problem of longitudinal welded support on wave

propagation

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Solution of Longitudinal welded support on

wave propagation

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Effect of contents, coatings and general

corrosion

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Effect of Pipe Contents Gases No Effect

Liquids and sludge have same effect Viscosity (fluid Fraction) depends on different fluids and

temperature

The viscosity of liquids decreases as the temperatureincreases

Liquids of Low Viscosity Almost no effect on the torsional mode

Affects the longitudinal mode test

Liquids of high viscosity (Asphalt or wax) and sludge Heavy viscous liquid or sludge of heavy depends attenuate

the signal and reduce the test range.

Insulation, Coating and Wrappings

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Mineral wool insulation- no effect Operates at 32, 64, 128, and 250kHz

PaintImproves the signal

Operates at 32, 64, 128, and 250kHz

Epoxy Coating Small effect (~ 1dB/m) Operates at 32, 64 kHz

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