NDT-Nondestructive Examination

8/10/2019 NDT-Nondestructive Examination

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MATERIAL CLASSIFICATION

Metal

MATERIAL

Nonmetal

Ferrous

Nonferrous

Raw

Product

Raw

Product

Organic

Anorganic


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THE IMPORTANCE OF TESTING

Simple & low risk

Complicated & high risk

QUALITY ASSURANCE !!!


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NONDESTRUCTIVE

DESTRUCTIVE

TYPES OF TESTING

No/minor change to the material being examined

Early warning, no need to shutdown the operation, qualitative &

quantitative information may be obtained

Potentially causes significant change to the material being

examined

Used as statistical sampling basis only, not suited to huge and

expensive structures


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Visual, with or without aidLiquid Penetrant Testing (PT)

Magnetic Particle Testing (MT)

Propagation of Elastic Waves/VibrationUltrasonic Testing (UT)

Acoustic Emission (AE)

RadiationRadiography Techniques (X-Ray, Gamma-Ray)

Electromagnetic FieldEddy Current Testing (ET)

Alternating Current Potential Drop (ACPD)

Alternating Current Field Measurement (ACFM)

TYPES OF NONDESTRUCTIVE TESTING


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TYPES OF DESTRUCTIVE TESTING

Mechanical TestTensile test: weld metal, weld joint, nick break

Bend test: face bend, root bend, side bend

Charpy impact test: V-notch, U-notch, keyhole

Hardness test: Brinell, Vickers, RockwellFracture test: fillet weld

Fatigue Test

Chemical Composition Test

Metallurgical TestFractography

Macrography

Micrography


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TENSILE TEST


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BEND TEST


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CHARPY IMPACT TEST


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Fatigue Test


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Chemical Composition Test

ARL Spectrometer

Niton

X-Ray Fluorescence (XRF)


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Metallurgical Test


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What are Some Usesof NDE Methods?

Flaw Detection and Evaluation

Leak Detection

Location Determination

Dimensional Measurements

Structure and Microstructure Characterization

Estimation of Mechanical and Physical Properties

Stress (Strain) and Dynamic Response Measurements

Material Sorting and Chemical Composition Determination

Fluorescent penetrant indication


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When are NDE Methods Used?

To assist in product development

To screen or sort incoming materials

To monitor, improve or control manufacturing

processes

To verify proper processing such as heattreating

To verify proper assembly

To inspect for in-service damage

There are NDE application at almost any stage

in the production or life cycle of a component.


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Six Most Common NDTMethods Visual Liquid Penetrant

Magnetic

Ultrasonic

Radiography Eddy Current


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Most basic and common

inspection method.

Tools include

fiberscopes,

borescopes, magnifying

glasses and mirrors.

Robotic crawlers permit

observation in hazardous or

tight areas, such as air

ducts, reactors, pipelines.

Portable video inspection

unit with zoom allows

inspection of large tanks

and vessels, railroad tank

cars, sewer lines.

Visual Inspection


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DIRECT VISUAL INSPECTION


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INDIRECT VISUAL INSPECTION


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INDIRECT VISUAL INSPECTION


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However, reliability of visual inspection is

highly affected by human factor since evenan experienced personnel can be fooled by

the presence of scratches or machining

marks into seeing defects which are not

present.

Due to the reasons, there are some aids to

visual inspection which help to revealdefects more readily and consistently.

Li id P t t I ti


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A liquid with high surface wetting characteristics is

applied to the surface of the part and allowed time to

seep into surface breaking defects.

The excess liquid is removed from the surface of

the part.

A developer (powder) is applied to pull the

trapped penetrant out the defect and spread it on

the surface where it can be seen.

Visual inspection is the final step in the process.

The penetrant used is often loaded with a

fluorescent dye and the inspection is done under

UV light to increase test sensitivity.

Liquid Penetrant Inspection


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HISTORY

The oil and whiting method was the

forerunner of modern liquid penetrant testing.The oil and whiting (chalk) method was used

in the early 1900s by the railroads in testing

locomotive parts such as axles, crank pins,and couplers.


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TYPE OF PENETRANT MATERIALS

Water-washable Post-emulsifiable

Solvent Removable

Either a color contrast (visible) penetrant or afluorescent penetrant shall be used with one of the

following three penetrant processes:

P t l ifi bl


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Post-emulsifiable


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Water-washable and Solvent-removable


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LIQUID PENETRANT INSPECTION

(Solvent-removable)


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Indication of Discontinuity


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Kelebihan: Sederhana & relatip murah.

Untuk semua material asalkan permukaannya, tidak berpori dan tidak

menyerap cairan.

Untuk komponen-komponen dengan semua bentuk dan ukuran.

Dipakai untuk quality control dan inline inspectionrutin.

Kelemahan:

Hanya untuk mendeteksi cacat permukaan.

Diperlukan akses untuk pembersihan permukaan.

Dapat mengecoh akibat adanya false indicationsdan nonrelevant

indications.

Tidak menunjukkan kedalaman cacat.

Pembersihan permukaan adalah critical.

LIQUID PENETRANT INSPECTION


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Magnetic Particle Inspection

The part is magnetized. Finely milled iron particles coated with a dyepigment are then applied to the specimen. These particles are attracted

to magnetic flux leakage fields and will cluster to form an indication

directly over the discontinuity. This indication can be visually detected

under proper lighting conditions.


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Direction of Magnetization

Circular Magnetization


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Longitudinal Magnetization

Direction of Magnetization


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MAGNETIC PARTICLE INSPECTION


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1. Material

2. Garis gaya magnet

3. Void/flaw

M ti P ti l C k


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Magnetic Particle CrackIndications


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S iti it f M ti P ti l


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Sensitivity of Magnetic ParticleSystem


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ULTRASONIC INSPECTION

1. Transducer/probe

2. Couplant

3. Material

4. Void/flaw

5. Layar CRT

6. Indikasi permukaan depan

7. Indikasi void

8. Indikasi back wall.


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ULTRASONIC INSPECTION EQUIPMENT


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ULTRASONIC INSPECTION EQUIPMENT


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ULTRASONIC THICKNESS GAUGE


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Kelebihan: Tidak menimbulkan bahaya radiasi.

Peralatannyaportabledan mudah dibawa-bawa.

Dapat dipakai untuk mendeteksi dan sekaligus menentukan letak dan ukuran

internal discontinuitiespada material-material logam dan non logam.

Cacat planar dapat dideteksi dengan mudah.

Keterbatasan:

Diperlukan operator yang terlatih dan trampil.

Pemilihan frekuensi tergantung pada jenis material yang diperiksa.

Diperlukan couplant.

Nonrelevant indicationsdapat terjadi akibat bentuk komponen, cacat-cacat yang

membentuk sudut, dan adanya pantulan.

Tidak dapat dipakai untuk memeriksa material dengan tebal kurang dari 5 mm

(adanya dead zone).



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RADIOGRAPHY TESTING


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RADIOGRAPHY TESTING


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Tabung Sinar X

RADIOGRAPHY TESTING


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RADIOGRAPHY TESTING

Isotop dan Kamera gamma ray


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Kelebihan: Mampu mendeteksi cacat-cacat internal.

Untuk memeriksa material-material logam dan non-logam.

Untuk memeriksa raw material dan hasil las.

Menghasilkan rekaman permanen dari komponen yang diperiksa.

Keterbatasan:

Harga peralatan dan beaya pengoperasian relatip mahal.

Bahaya radiasi.

Waktu set-up lama.

Cacat-cacat planar sulit terdeteksi.

Diperlukan akses dari kedua sisi komponen.

Perhitungan tegangan, exposure time, Source to Film Distanceadalah

critical.

RADIOGRAPHY TESTING


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EDDY CURRENT TESTING


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Applications

Surface crack detection

Non-ferrous metal sorting

Sub-surface crack/corrosion detection

Heat exchanger tube testing

In-line inspection of Steel tubing

Ferrous weld inspection



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EDDY CURRENT APPLICATION


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EDDY CURRENT EQUIPMENT


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EDDY CURRENT EQUIPMENT


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Kelebihan: Immediate assessment of crack depth and length.

Can be used to measure coating thickness.

Can be used to determine physical properties of materials.

Can be used for high-speed automatic inspection.

Keterbatasan:

Non-contacting, but close proximity of probe onto surface is required.

False indication as a result of local variation in permeability or physical

metallurgy, edge effect, and lift-off effects.

Calibration is critical prior to inspection. Low penetration power, limited to near surface flaws.

Applicable only to electrically conductive materials.

ACCOUSTIC EMISSION TECHNIQUE


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Schematic diagram for an acoustic emission technique.

Test Component

PreamplifierBand pass

filter AmplifierMeasurement

circuits

Data buffers

Microcomputer Audio monitor

Visual monitor

X-Y recorder

Sensor


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ACCOUSTIC EMISSION SIGNALS


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ACCOUSTIC EMISSION SIGNALS



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Kelebihan:

Dapat memonitor daerah/area yang luas.

Continuous monitoring.

Teknik yang sensitif untuk memonitor timbulnya cacat pada struktur.

Keterbatasan:

Harga sistem peralatan yang sangat mahal.

Sensor/probe harus in contactdengan struktur.

Diperlukan accoustic couplingdan stressing source.

Interpretasi signal kadangkala rumit sehingga perlu operator yang terlatih.


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LEAK TESTING

LEAK TESTING


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LEAK TESTING

Water pressure test for water ballast pipes of 5 kg/cm2

LEAK TESTING


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LEAK TESTING

Water pressure test for water ballast pipes of 5 kg/cm2

LEAK TESTING


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LEAK TESTING

Hose test for hull butt joint of 300 bars

LEAK TESTING


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LEAK TESTING

Hose test for hull butt joint of 300 bars

LEAK TESTING


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LEAK TESTING

Air pressure test for double bottom of 0.25 kg/cm2

LEAK TESTING


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LEAK TESTING


LEAK TESTING


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LEAK TESTING



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POTENTIAL DROP TECHNIQUE

Probe

D

Contact pointContact point

Uniform potential currents

no crack between the two contact points.


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D

Contact pointContact point

h

Transversal crack

Probe

a crack between the two contact points.

2hD

V

D

V21

2

D

1V

V

h1

2


POTENTIA DROP TECHNIQUE


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Kelebihan:

Assessment of crack depth and length.

Can be used to monitor crack depth during service life of a component.

Accurate measurement is achieved on flat surface.

Keterbatasan:

Contacting technique requiring surface cleaning before testing.

False indication as a result of complex geometry, local variation in

permeability or physical metallurgy, edge effects, and lift-off effect.

Flaws should be oriented perpendicular to the current lines.


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ACFM Principle


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ACFM Principle

z

yx

Uniform current

Orientation of the magnetic fields on the surface of a component.

ACFM Principle


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Qualitative explanation of the nature of Bx and Bz above a defect.


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Noise in the ACFM signal.


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Scanning result of backwall defect in 6-Mo SS pipe.

ACFM Probe


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ACFM Probe

z x

Induction coil

Bz search coil Bx search coil

Pencil probe used with the ACFM technique.

ACFM Probes


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Standard Weld Probe Tight Access Probe Edge Effect Probe

Mini Pencil Probe Micro Pencil Probe Universal Thread Probe

Underwater Application


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Underwater ACFMCrack Microgauge Model U21

Underwater Application

Field Application


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ACFM/ACPD Crack Microgauge Model U9 (Field Use)

Field Application

Laboratory Application


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ACFM/ACPD Crack Microgauge Model U10

(Laboratory Use)

Laboratory Application

Array Probes


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ACFM Crack Microgauge Model U12

(Manual and Array ACFM Probes)

Array Probes

Advantages of ACFM Technique


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Advantages of ACFM Technique

Accurately measures depth and length of defect.

Ability to detect surface, subsurface or remote-surface defects in low

magnetic permeability materials.

Non-contacting technique.

Can inspect over rough surfaces and through coatings up to 5 mm

thick.

Rapid and cost effective inspection can be achieved. No need to calibrate the instrument prior to each use.

Provide data storage for off-line analysis.

Limitations of ACFM Technique


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q

Only applicable for inspecting electrically conductive materials.

Gives better results for flat or smooth surfaces.

Flaws should be oriented perpendicular to the electric field direction.

Materials to be inspected should be demagnetise.


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QUALIFICATION FOR NDT PERSONEL


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NDT-Nondestructive Examination

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