Ndt Methods.doc

5/24/2018 Ndt Methods.doc

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Visual Testing ( VT )

Penetrant Testing ( PT )

Magnetic Particle Testing ( MPT )

Ultrasonic Testing ( UT )

Radiography Testing ( RT )

Eddy Current Testing ( ECT )

Leak Testing ( LT )

Accoustic Emission Testing ( AET )

Thermal Infra Red ( TIR )

Neutran Radiographic Testing ( NRT )


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REQUIREMENTS OF NDT PERSONNELQUALIFICATION

SNTTC1A - Recommended Practice for Non-destructiv

Testing Personnel Qualification and Certification

ASNTCP189 - ASNT Standard for Qualification and Certificatio

Of Non-destructive Testing Personnel.

ASNT - American Society For Non-destructive Testing Personnel.

ISNT - Indian Society For Non-destructive Testing Personnel.

LEVEL OF QUALIFICATION

Level I - Operator

Level II - Inspector / Interpretor

Level III - Authorise to write a NDT procedure and Training &

Certification of NDT Personnel.


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LIQUID PENETRANT TEST ( LPT )

History - Oil & Whiting Method For Rail Road

Principle - Capillary Action of Penetrant&

Blotting Action of Developer

Application - To detect the discontinuities (e.g. Cracks,Seams, Laps, Lamination & Porosity etc.) open to thesurface in non porous materials.

Equipment

.Cleaner - Solvent or Water

. Penetrant - Oil base with Dye

. Developer - Chalk powder

Addition of the above Linen cloth, Cotton waste orabsorbent paper for cleaning purpose.


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BASIC STEPS INVOLVED IN LPT

.SURFACE PREPARATION / PRE- CLEANING

.PENETRANT APPLICATION

.EXCESS PENETRANT REMOVAL

.DEVELOPER APPLICATION

.DEVELOPING TIME

.EXAMINATION & EVALUATION

.RECORDING

.POST-CLEANING

TECHNIQUES(Visible or Fluorescent dye)

I) Water Washable

II) Post Emulsification

III) Solvent Removal


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Properties of Developer

- Blotting Action

- Contrast Background

Properties of Penetrant

-Wetting ability

-Surface Tension

-Capillary

-High fluidity

-Flash point

-Temperature stability

-Visibility

-Volatility

-Corrosive property

i) Sulfur free - for In base alloy

ii) Halogen free - for Austenitic SS and


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TESTING OF PENETRANTS

.Chrome Sensitivity Panel

.Aluminum Comparator Block

.Fluorescence Comparison Test

.Visibility

.Drying Test

LIMITATIONS OF DPT

- Can not give the indication for depth.

- Poor repeatability of test.

-Retest should be done with same type of

penetrant only.

- Not suitable for porous material.

- Not applicable for hidden defects.


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LIQUID PENETRANT STANDARDS

ASME SEC-V (ARTICLE - 22)

SE-165-91

Standard Practice for Liquid Penetrant InspectionMetho

SE-1209-91

Fluorescent Penetrant Examination using water washablprocess.

SE-1219-91

Standard Testing Method for Fluorescent PenetraExamination using Solvent removable Process

SE-1220-91

Standard Test Method for visible PenetrantExamination usingsolvent removable


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PRINCIPLE

Uses Electro-Magnetic Waves of very short wavelengths (X - rays and Gamma Rays) to penetratematerial and the transmitted energy records theimage of discontinuity of the material on the film.

APPLICATIONS

Used on any material, metal & weld to detectsurface of internal detects. Film provides apermanent record.

LIMITATIONS

High Initial cost and potential safety hazard topersonnel.


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SOURCE OF RADIATION

i. Electrically energised equipment. The rays

are called x-rays.ii. Radioactive material. The emitted rays arecalled Gamma Rays.

In x-ray machine the energy level and output can bevaried.

In GammaEquipment the energy level is constant for aparticular type of source and output is constant for andindividual source.

Higher the energy level, greater is the penetratingpower.

HALF LIFE - Strength of source reduces with the timeand when it becomes half of the actual

strength, its known as half life.

Isotopes Half life

Iridium 192 74 days

Thulium 170 128 days

Cobalt 60 5.3 yrs.

Cesium 137 33 yrs


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SENSITIVITY

It is a measure of the ability to detect thesmallest dimension of discontinuity in theradiograph.

Sensitivity is a function of "Definition" and"Contrast".

DEFINITION DEPENDS ON

i. Geometric Un-Sharpness(Penumbra Effect)

ii. Film Grain Size

CONTRAST DEPENDS ON

i. Energy Levelii. Inherent Contrast of Filmiii. Fog Level of Film

iv. Scatter Radiation.


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DENSITY

It is a measure of degree of darkness of film. It is

expressed in 10 Base Log Scale.

DENSITY LIMITS

x-rays - 1.8 to 4.0Gamma Rays - 2.0 to 4.0

ROENTGEN

It is the amount of ionising radiation whichwould produce one Electro static unit of charge ina cubic centimetre of air at standardtemperature (00c) and pressure (760mm Hg)

CURIE

It is a measure of radioactivity or strength osource. It is defined as 3.7 x 1010 Dis-integrations

per second.


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RADIOGRAPHIC TECHNIQUE

1. SINGLE WALL TECHNIQUE

i. Single Shot Technique.ii. Panoramic Technique.

2. DOUBLE WALL TECHNIQUE

i. Double Wall Single Imageii. Double Wall Double Imageiii. Double Wall Superimposed

GEOMETRIC UNSHARPNESS (Ug)

Ug = f x td

where,f = Focal spot size of source of radiation

t = Thickness of object.D = Distance between source of radiation

and the object.


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Ug Limits as per ASME Section V, Article 2

Thickness Range Maximum Ug

Upto2" Thickness 0.020"2" to 3 0.030"3" to 4" 0.040"4" and above" 0.070"

PENETRAMETER

1. WIRE TYPE

I) ASTM STANDARD

II) DIN STANDARD

2. HOLE TYPE

INDUSTRIAL FILMS

I) SLOW SPEED

II) MEDIUM SPEED

III) HIGH SPEED


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RADIOGRAPHIC STANDARDS

ASME - SECTION - V (ARTICLE - 22)

SE94Standard Practice for Radiographic Testing.

SE186Standard Reference Radiographs for Heavy Walled(2" to 4 1/2") Steel Castings.

SE280Standard Reference Radiographs for Heavy Walled(4 1/2" to 12") Steel Castings.

SE - 446Standard Reference Radiographs for Steel Castingsup to 2" Thickness

SE747Standard Method of Controlling Quality ofRadiographic Testing using wire penetrameter.

SE - 1025

Standard Practice for Hole Type image qualityindicators used for Radiography.

SE1079Standard Practice for calibration for Transmission


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Magnetism - A part is magnetized when some or allof the molecules within the parts are aligned.

N S

Random orientation Aligned moleculesof molecules ( Magnetized)n- Magnetized )

CLASSIFICATION OF MATERIAL

.Diamagnetic - Very difficult to magnetized e.g.Hg, Au, Zn, Bi

.Paramagnetic - Accept only slight magnetism

e.g. Al, Cu, wood, Pt , Sullphate

.FerromagnetismCan be magnetized stronglye.g. Fe, Co, Ni,


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MAGNETIC PARTICLEINSPECTION

PRINCIPLE

Uses electrical current or permanent magnetto create a magnetic field in a specimen,andflux leakage occurred at discontinuity.

Magnetic particles cumulate on flux leakageand indicate the discontinuity.

APPLICATIONS

Used on metal which can be magnetised

(Ferromagnetic) to detect surface or sub-surface discontinuities. Simple to use andportable for field testing.

LIMITATIONS

Cannot be used on metals, which cannot bemagnetised.


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CLASSIFICATION OF M.P. TEST METHODS

A. CIRCULAR MAGNETIZATION

1. DIRECT INDUCTION

i. HEAD SHOT METHODBy passing current through the material.

ii. PROD MAGNETIZATION

Where size and location does not permit tuse Head Shot or Central Conductor method

2. INDIRECT INDUCTION

By placing a current carrying conductor into thspecimen.

B. LONGITUDINAL MAGNETIZATION

1. COIL OR SOLENOID METHOD

When the length of specimen is several time

its diameter or cross section - this method used by placing it length wise in the field.

2. YOKE TYPE

It is a horse shoe magnet made byelectrically energising it or by the use of a

permanent magnet.


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YOKE TECHNIQUE

i. Direct Current Yoke

ii. Alternate Current Yokeiii. Permanent Magnet Yoke

MPT METHODS

1. Based on Magnetic Particle type

a) Visibleb) Fluorescent

2. Based on Magnetic Particle Application

a) Dry

b) Wet

CHECKING OF YOKE

LIFTING POWER

i. DC Type & Permanent Min.Weight - 40 Lbs.

( At Max. Pole Spacing )

ii. AC type Min.Weight - 10 Lbs.(At Max. Pole Spacing )


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Eight low carbon steel pie sections, Furnace brazed together

1 in. Non Ferrous handle

of any convenient length

Artificial flaw (All segment interfaces) 1/32 in. max.

Brazed weld or mechanically attach Non-ferrous trunnions

Copper Plate 0.010 in. 0.010 in. thick

1/8 in.

ASTM Magnetic Particle Field Indicator

MAGNET PARTICLE STANDARDS ASME SECTION V (ARTICLE 25)

SE-709Standard practice for Magnetic Particle

Examination


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PRINCIPLE

Uses ultrasound wave to penetrate material, indicating

discontinuities on Oscilloscope Screen.

APPLICATIONS

Used on metals, ceramics, plastics, etc. to detectsurface and internal discontinuities. When automated,

indications are recorded on paper, it provides apermanent record. Also used for measuring thickness.

LIMITATIONS

Moderately high initial cost. Interpretation of test

results requires highly trained personnel.


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TYPE OF ULTRASONIC WAVES

1. LONGITUDINAL (OR COMPRESSION) WAVES

2. TRANSVERSE (OR SHEAR) WAVES

3. SURFACE WAVE

4. PLATE ( LAM B ) WAVES

PROPERTIES OF ULTRASONIC BEAM

1. Travel in a straight line.

2. Reflect and refract from the boundary of different

acoustic media.

3. .Attenuate while passing through a media.

4. The extent of attenuation depends on

- Absorption ( dependent on grain size )

- Diffraction or spreading (dependent on wavelength and probe diameter )

5. Velocity in a media depends on the density &elastic constants. The values for differentmedia's are given in the following chart.


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TECHNIQUES

1. Contact Testing2. Immersion testing

DATA PRESENTATION

1. `A' SCAN METHOD

This method is commonly known as Pulse EchMethod. Time versus Amplitude display showon Cathode Ray Tube.

2. `B' SCAN METHOD

This method displays cross sectionalview.

3. `C' SCAN METHOD

This method displaysplanview and comparablto radiographic image.

NOTE:-More than 90 % of total Ultrasonic Examinations arcarried out by "A" Scan Method.


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METHODS

.PULSE-ECHO

.THROUGH TRANSMISSION

.RESONANCE

TYPES OF PROBES

I. SINGLE CRYSTAL NORMAL BEAM PROBE.

II. SINGLE CRYSTAL ANGLE BEAM PROBE.

III. TWIN CRYSTAL PROBES.


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"DAC" CURVE

Same size of defect or reference reflector atdifferent distance/depth give's different signalamplitude because of attenuation of ultrasonicbeam in medium. As such defect Amplitudecorrection Curve has to be drawn as shown in fig.

T/2

T/2

SDH 2.4 mm


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ULTRASONIC STANDARD

SA - 388Recommended practice for Ultrasonic testing aninspection of heavy steel forging.

SA - 435Standard specification for straight beam ultrasonexamination of steel plates.

SA - 577Standard specification of ultrasonic angle bea

examination of steel plates.

SA - 578Standards specification for straight beam ultrasonexamination of plain and clad steel plates of speciapplication.

SA - 609Standard specification for longitudinal ultrasoninspection of carbon and low alloy steel casting.

SA - 745Standard practice for Ultrasonic examination of austenitsteel forging.

SE - 213Standard practice for ultrasonic inspection of metal pipand tubes.

SE - 797Standard practice for thickness measurement by manu

contact ultrasonic method.

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Ndt Methods.doc