Engineering schools INP

1. Les Controles Non
Destructifs
methodes d’expertise
Fjguillou, Meylan 30 mars 2017

2. References:
“Introduction to Nondestructive Testing - A Training
Guide”, P. E. Mix, John Wiley & Sons.
“NDE Handbook - Non-destructive examination
methods for condition monitoring”, ed. K. G. Bøving,
Butterworths
ASME V code NDT for pressure vessels
Guides UIC/UFIP CTNIIC 2008, Paris
COFREND /BINDT normes, procedures CND
Fiabilite industrielle , Arco /Lyondell , Houston
IS Paris Cours ESSA / IRSN/ CEA/ TWI
The china syndrom us movie 1979
Techniques de l’Ingenieur
09/05/2017 2

3. utilisation de
techniques non intrusives pour
determiner
l‘ integrité des : materiaux,
composants , equipements
structure , appareils ,usines
par une analyse physico
chimique et une mesure
quantitative de leurs
caracteristiques ,
Sans en modifier l’ usage,
durant leurs cycles de vie
Definition des CND
09/05/2017 3

4. Pourquoi Non destructif ?
• Controles des equipement en service
• Equipement souvent trop “precieux”
pour etre detruit
• Equipement reutilisable après controles
• Finalité en gestion de la qualité
• Sans douleur pour l’equipement
• Video support illustration
09/05/2017 4

5. UTILITE des techniques de CND 1
• En conception/construction / reparation
– Controle qualite des elements /pieces d’equipement ex :
Segregation /Acceptation de defauts mineurs
– Conformite aux codes normes , reglementations et regles de
l’art par des controles a toutes les etapes de la construction
– Estimation des caracteristiques physiques, chimique , electro
Mecaniques , thermique de la matiere, des materiaux Vs les
plans et specifications d’origine
– ,Controles quantitatifs , Tri selectif de matiere
– Reception des equipements /aptitude avant leur mise en
service
– Analyses de risques /fiabilite
09/05/2017 5

6. UTILITE des techniques de CND 2
• En Service / Exploitation
– Prevention des risques de pannes , diagnostics
– Outils de diagnostic de l’evolution des modes de degradation
– Plans d’inspection pour la connaissance de l’etat des
equipements des sites Seveso/ Centrales nucleaires , ….
– Estimation de la durée de vie residuelle des equipements
d’une usine process ,analyses de risques
– Espacement des arrets de maintenance ( usines ,avions,
vehicules, centrales,..)
– Surveillance de parametres critiques d’exploitation
– RBI analyse de risques Integrite des Assets
09/05/2017 6

7. UTILITE des techniques de CND 3
• Expertises lors :des Arrets programmés / des pannes
– Etat des lieux , gravité des composants endommagés, zonage
– diagnostic evolutif des modes d’endomagement ou de degradation (
ex : corrosion,fatigue ,fluage, incendies,/explosions, …)
– Analyse des causes de pannes ,Arbre des causes
– Mises a jour des Plans d’inspection/controles pour la connaissance
de l’etat permanent des equipements des sites Seveso/ Centrales
nucleaires , Aerospatiale, genie civil ,medical …
– analyses de risques ,previsions en fiabilite, ex : Estimation
quantitative de la durée de vie residuelle des equipements d’une
unité process , d’un vehicule , d’une centrale nucleaire, usine
petrochimie, avions , trains,navires ,pipelines …
– Espacement des arrets de maintenance ( usines ,vehicules)
– Surveillance de parametres critiques d’exploitation
– Retour d’experience en fiabilité , formation, expertise technique
09/05/2017 7

8. The China Syndrom
• Explication orale a partir d’un resumé du film americain
• TMI three miles island fusion du coeur reacteur ,accident 1979
09/05/2017 8

9. • Detection defauts et Evaluation
• Detection de fuites
• Localisation Determination taille
• Mesures Dimensionnelles
• Caracterisation Structure et Microstructure
• Estimation des Proprietes Mecaniques et Physiques
• Stress (Strain) et mesures de Reponses Dynamiques
• Tri de Matieres et Determination desComposition
Chimique
Fluorescent penetrant indication
UTILITE des techniques de CND 4
09/05/2017 9

10. Principales techniques de CND
• Detection des indications externes de surface ou sous jacents
Visuel/ Endoscopie
Magnetoscopie lumiere noire ou fluorescente
Ressuage rouge ou fluorescent
Etancheite, Epreuves et jauges de contraintes
Courants de Foucault
Protection cathodique et DCVG
Thermographie infra rouge
• Detection des indications internes
Radiographie X et Gamma
Ultrasons , Tofd et Phased array
Emission acoustique et
MFL :saturation magnetique fuite de flux
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11. 09/05/2017 11

12. 09/05/2017 12

13. basique et commode
methode de contrôle .
Outils :fibroscopes,
borescopes, magnifying
glasses and mirroirs.
Robots crawlers pour
observation en lieux
hazardeux ou inaccessible ,
tel tuyaux reacteurs,
pipelines.
Portable video inspection
avec zoom permet
inspection of large
capacites , cars, lignes.
1. Inspection Visuelle
09/05/2017 13

14. 2. Magnetic Particle Inspection (MPI)
2.1 Introduction
• Non destructive methode utilisée en detection de defaut .
• MPI utilise le champ magnetique et les particules magnetiques, tel la
poudre de fer pour detecter les indications dans les composants. La
seule exigence est que le composant controlé soit en materiau
ferromagnetique ex : fer , nickel, cobalt, et certains alliages .
• La methode sert à controler une varieté de produits tel les forgés
moulés, soudés,
• Exemples d’ industries utilisant la magnetoscopie : structures metal ,
auto, petrochemical, centrales electriques , aerospatial industries.
inspection Sousmarines offshore structures ou pipelines.
09/05/2017 14

15. 2.2 Principes de Base
En theorie, la magnetoscopie (MPI) est un
principe relativement simple . On le considere
comme une combinaison de deux techniques non
destructive : magnetic flux leakage testing MFL et
examen visuel .
Considerons un barreau magnetique. Il possede
un champ magnetic , une ligne de force qui
entre ( au Sud) et sort ( au Nord) et sont appelés
poles.
C’est la boussole placée dans le champ
magnetique terrestre
09/05/2017 15

16. Interaction d’un materiau avec un champ
magnetique externe
Si un materiau est placé dans un champ magnetique, les
forces actives des electrons du materiau sont affectés
Cet effet est connu : la Loi de Faraday en Induction.
Magnetique, et la force d’attraction magnetique
Ceoendant les materiaux peuvent reagir differemment à la
presence d’un champ magnetique externe . Cette reaction
depend du nombre de facteurs tel la structure atomique
et moleculaire , des moments magnetiques associés aux
atomes et qui ont trois origines :
L’orbitale de l’electron , le changement de l’ orbite causé
par un champ magnetique externe , et le spin de
l’ electron sur lui meme .
09/05/2017 16

17. Materiau Ferromagnetique Il devient magnetique quand les
dipoles magnetiques du materiau sont alignés. en plaçant le
materiau dans un puissant champ magnetic externe ou en faisant
passer un courant electrique dans le materiau. Les dipoles sont
aligne en partie ou totalement. La puissance du champ en depend
. Quand tous les dipoles sont alignes,on obtient la saturation
magnetique hysteretique. Des lors aucune augmentation de
champ ne causera aucun effet additionnel interne de
magnetisation.
Materiau non magnetisé magnetisémateriau
09/05/2017 17

18. Proprietes Generales des Lignes de champ
• suivent le chemin de moindre
resistance entre les poles.
• pas d’interactions des lignes .
• symetrie d’ intensite .
• la densité decroit en fonction de la
permeabilité du milieu
•la densité du champ decroit avec la
distance .
09/05/2017 18

19. Magnetic Particle Inspection
• Les lignes de flux magnetic pres de la surface
d’un material ferromagnetic tend a suivre le profil
de surface du materiau
• Les discontinuites (cracks or vides) du materiau
perpendiculaires aux lignes de flux lines causent
des compression et des fuites de magnetic flux
lines, i.e. flux leakage
• Les fuites creent des dipoles magnetiques qui
attirent d’autres particules ferromagnetic
09/05/2017 19

20. Si un barreau magnetique se divise en deux , 2 poles
magnetiques se creent a chaque extremite de piece . Si le
barreau est seulement fissuré , un pole nord et un sud se
forment a chaque extremite de fissure
09/05/2017 20

21. Si des particules de fer sont etalées sur une zone fissurée
magnetisée, les particules seront attirées aux dipoles formé aux
bords de la fissure . Cet quantite de particules est plus facile a
observer que la fissure elle meme and ceci est la base du controle
magnetic particle inspection.
09/05/2017 21

22. Les Cracks sous la
surface sont egalement
revelés, les fissures
dans le sens du champ
ne sont pas detectees
Les particules magnetiques
forment un effet de ride plus
large que la fissure , rendant
celle ci plus visible
09/05/2017 22

23. 2.3 Procedure Test MPI
• nettoyage
• Demagnetisation tunnel reduction hysteresis
• Contraste (e.g. white paint for dark particles)
• Magnetisation de l’object, temoin de berthold
• Addition de particulesmagnetiques Illumination
Durant inspection (e.g. UV Hood lampe)
• Interpretation
• Demagnetisation – prevenir de l’ accumulation
particules de fer ou influence sensible aux
instruments
09/05/2017 23

24. L’ efficacité MPI depend de
l’orientation de la fissure vs
les lignes de champ
MPI est peu sensible aux
indications de perte d’epaisseur ,
comme MFL peut l’etre
09/05/2017 24

25. Magnetisation de la la piece
• magnetisation Directe : un
courant passe directement
a travers le composant.
composant entre 2 contacts electriques
pinces en contact avec le composant
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26. magnetisation Indirecte :
par champ externe
magnetique
(a) permanent magnets
(b) Electromagnets
(c) coil shot
09/05/2017 26

27. • magnetisation Longitudinale
• aimant permanent ou
electromagnets
•magnetisationCirconferentielle :
un courant electrique passe dans
la piece
09/05/2017 27

28. Demagnetisation
After conducting a magnetic particle inspection, it is usually
necessary to demagnetize the component. Remanent magnetic
fields can:
• affect machining by causing cuttings to cling to a component.
• interfere with electronic equipment such as a compass.
• can create a condition known as "ark blow" in the welding
process. Arc blow may causes the weld arc to wonder or filler
metal to be repelled from the weld.
• cause abrasive particle to cling to bearing or faying surfaces
and increase wear.
09/05/2017 28

29. particules magnetiques
• iron oxide Pulverised(Fe3O4) or
carbonyl iron powder
• poudre Coloree ou fluorescente
magnetique ameliore la visibilité
• Powder can either be used dry or
suspended in liquid
09/05/2017 29

30. Standards MPI
• British Standards
– BS M.35: Aerospace Series: Magnetic Particle Flaw
Detection of Materials and Components
– BS 4397: Methods for magnetic particle testing of welds
• ASTM Standards
– ASTM E 709-80: Standard Practice for Magnetic Particle
Examination
– ASTM E 125-63: Standard reference photographs for
magnetic particle indications on ferrous castings
• etc….
09/05/2017 30

31. • Rapide , simple et peu couteux
• indication de surfacedirect, visible
• Fiable et precis
• Peut etre utilise sur la peinture
• preparation surface non requis
2.4 Avantages MPI
09/05/2017 31

32. 2.5 Limites MPI
• Seulement pour materiaux ferromagnetiques
• direction entre les lignes de champ magnetique et le
defaut est important
• Les objets doivent etre demagnetises avant et apres
examen
• Le courant electrique de magnetisation peut causer
des brulures ou trempe de metal a la piece
09/05/2017 32

33. Exemples magnetiques indications
Indication of a crack in a saw blade Indication of cracks in a weldment
Before and after inspection pictures of
cracks emanating from a hole
Indication of cracks running between
attachment holes in a hinge
09/05/2017 33

34. Exemples de Fluorescence en lumiere noire Indications
Particules Magnetiques
Magnetic particle lumiere noire
fluorescente , indication de cracks sur un
arbre de vehicule
Magnetic particle wet
fluorescent
indication fissure
dans un roulement
Magnetic particle fluorescent indication de
fissure au trou de fixation
09/05/2017 34

35. 09/05/2017 35
Exemples de Fluorescence en lumiere noire Indications
Particules Magnetiques

36. 3. controle par Ressuage
Popularite du controle attribuée aux
Materiaux divers :
metaux (aluminum, cuivre, acier, titane, etc.),
verres /glass,
Ceramiques
Caoutchouc rubber,
plastiques.
09/05/2017 36

37. 09/05/2017 37

38. • La technique est basee sur le mouillage et la capillarite d’un
liquide a faible tension superficielle repandu sur une surface
controler , en application de la loi de jurin .
• Apres une periode d’impregnation l’exces surfacique de
penetrant est enlevé et un developpeur y est appliqué . Effet
talc ou buvard
• Examen en lumiere blanche( colorant rouge sur talc blanc ) ou
lumiere noire UV methode aaplicable aux materiaux non-
ferromagnetique
• detection de fissures de largeur 2µm
• Standard: ASTM E165-80 Liquid Penetrant Inspection Method
3.1 Introduction
09/05/2017 38

39. 09/05/2017 39

40. Penetrant Types
Dye penetrants
– The liquids are coloured so that
they provide good contrast
against the developer
– Usually red liquid against white
developer
– Observation performed in
ordinary daylight or good indoor
illumination
Fluorescent penetrants
– Liquid contain additives to give
fluorescence under UV
– Object should be shielded from
visible light during inspection
– Fluorescent indications are
easy to see in the dark
Standard: Aerospace Material
Specification (AMS) 2644.
09/05/2017 40

41. 4. Radiographie
Radiography involves the use of penetrating
gamma- or X-radiation to examine material's
and product's defects and internal features. An
X-ray machine or radioactive isotope is used
as a source of radiation. Radiation is directed
through a part and onto film or other media.
The resulting shadowgraph shows the internal
features and soundness of the part. Material
thickness and density changes are indicated
as lighter or darker areas on the film. The
darker areas in the radiograph below represent
internal voids in the component.
Haute tension continue
Electrons
-+
X-ray Generateur ou
Source Radioactive
de Radiation
film
Penetration
des Radiation
dans l’objet
09/05/2017 41

42. 4.1 sources de radiation
X-rays or gamma rays
• X-rays sont des radiations
electromagnetic de courte
longueur onde (≈ 10-8 -
10-12 m)
• Energy des x-ray par l’
equation E = hν = hc/λ
le photon x-ray de
longueur d’onde 1Å a
une energie de 12.5
keV
09/05/2017 42

43. target X-rays
W
Vacuum
Production de rayons X
Les rayons X sont
produits par des
electrons rapides en
collision avec un
metal cible
•source electrons – W
filament de tungstene chaud
d’intensite I
•Haute tension continue V
d’acceleration
(100-400kV) entre cathode
et anode ou cible metal
• anode refroidie via un bloc
de Cuivre contenant le
metal cible .
09/05/2017 43

44. Spectre de rayons X
• Le spectre de x-ray est produit
par le retour a l’orbite d’equilibre
des electrons cibles energisés
par le choc des electrons
rapides incidents
• Le spectre continu et le
spectre de raies.
SWL - short-wave length limit
continu
radiation
characteristic
radiation
kα
kβ
I
λ
09/05/2017 44

45. • All x-rays are absorbed to some extent in passing through
matter due to electron ejection or scattering.
• L’ absorption suit l’equation
where I est l’intensité/energie transmise ;
x epaisseur materiau;
µ coefficient absorption lineaire (element dependent);
ρ densité matiere;
(µ/ρ) coefficient absorption massique (cm2/gm).
Absorption des rayons X
x
x
eIeII
ρ
ρ
µ
µ 





−
−
== 00
I0 Iρ,
µ
x
09/05/2017 45

46. Diverses sources de rayonnement
E Nat ≈ 3 mSv / an

47. 4.1.2 Radio Isotope (Gamma) Sources
Les Rayons gamma sont un des trois source types de radioactivite. It is
the most energetic form of electromagnetic radiation, with a very short
wavelength of less than 1/10 de nano-meter. Les rayons Gamma rays
emis principalement par des radios nucleides avec souvent des
particules alpha or beta .
U bombardement neutronique de la matiere rend celle ci instable et
radioactive par la desintegration du noyau et l’emission notamment de
rayons gamma
Les sources industrielles de Gamma-ray sont Iridium-192 and Colbalt-60.
. Cobalt 60 emet a 1.33 MeV gamma ray,iridium-192 emet à 0.31 MeV
gamma rays.
09/05/2017 47

48. Radio elements
09/05/2017 48

49. Principe de Radioactivité et d’Exposition
• L’énergie de désintégration d’un atome est transmise dans
une onde électromagnétique de haute fréquence sous la
forme de rayonnement radioactif.

50. Seuils de Radioprotection
Débit de doses maxi admissible: décret 2003-096 du 31/03/2003
Public
1mSv/an
Balisage
zone surveillée
Cat B
6mSv/an
zone contrôlée
Cat A
20mSv/an
zone interdite
Source radioactive
Catégorie A : Personnes dont les conditions habituelles de travail peuvent entraîner
le dépassement des 3/10ème des limites annuelles d'exposition
Catégorie B: Travailleurs exposés aux rayonnement ionisants ne relevant pas de la catégorie A
Public: Les travailleurs de catégorie A et B sont soumis à une surveillance médicale spéciale
Zone surveillée : (extrait de la procédure DMG 2102)
La zone surveillée est une zone dont l'accès est réglementé pour des raisons de protection contre les rayonnements ionisants. Le balisage de cette zone surveillée, qui est de
la responsabilité de l’entreprise de gammagraphie, doit être calculé de façon que les autres travailleurs de l’usine ne soient pas susceptibles de recevoir une dose efficace de
1mSv par an.Un débit de dose de 10microSv/h en limite de balisage est acceptable puisqu’il faut 100 h d’exposition pour atteindre cette limite.
09/05/2017 50
Débit de doses maxi admissible: décret 2003-096 du 31/03/2003
Public
1mSv/an
Balisage
zone surveillée
Cat B
6mSv/an
zone contrôlée
Cat A
20mSv/an
zone interdite
Source radioactive
Catégorie A : Personnes dont les conditions habituelles de travail peuvent entraîner
le dépassement des 3/10ème des limites annuelles d'exposition
Catégorie B: Travailleurs exposés aux rayonnement ionisants ne relevant pas de la catégorie A
Public: Les travailleurs de catégorie A et B sont soumis à une surveillance médicale spéciale
Zone surveillée : (extrait de la procédure DMG 2102)
La zone surveillée est une zone dont l'accès est réglementé pour des raisons de protection contre
les rayonnements ionisants. Le balisage de cette zone surveillée, qui est de la responsabilité de
l’entreprise de gammagraphie, doit être calculé de façon que les autres travailleurs de l’usine ne
soient pas susceptibles de recevoir une dose efficace de 1mSv par an.Un débit de dose de
10microSv/h en limite de balisage est acceptable puisqu’il faut 100 h d’exposition pour atteindre
cette limite.

51. 09/05/2017 51
Gammagraphes industriels

52. 4.2 Radiographie sur Film
Top view of developed film
X-ray film
La piece est placee entre la source et
le film. Epaisseur , et densite
attenueront les radiations.
= more exposure
= less exposure
• la noirceur (densité) du film
varie selon la quantite de
radiation qui atteint le film
• Defauts, ex: vides, fissures ,
inclusions, etc., sont detectes
•Tpose =f’( dfoc,ep,mat,film,ac
source) .
09/05/2017 52

53. Contraste et Definition
le contraste est fonction de
l’absorption des rayons par la
matiere
le reglage I,V du poste a rayons
x a spectre continu permet
l’optimisation du contraste ,
alors que les sources de rayon
gamma monochromatiques ne
le permet pas
Contraste
radiographique qualité image is radiographic contrast. Le
contraste radiographique est le degre de difference de densité
entre des zones adjacente d’ un radiogramme.
low kilovoltage high kilovoltage09/05/2017 53

54. 09/05/2017 54
Flou geometrique

55. Definition
Indicateurs de qualite d’image
09/05/2017 55
Exemple
d’indicateur de
qualité d’image (IQI)
normalisé :
AFNOR NF 09-205
Temps de pose :
T=f( d, e, f, s, ρ )
s :intensite source
f :type de film
e :epaisseur
ρ :densite materiau
d : distance focale

56. 4.3 Application
• defauts en epaisseur
• Vision interne d’un objet
• mesures dimensionnelles , ex epaisseurs de pipes
ASTM
–ASTM E94-84a Radiographic Testing
–ASTM E1032-85 Radiographic Examination of Weldments
–ASTM E1030-84 Radiographic Testing of Metallic Castings
Standards:
09/05/2017 56

57. 09/05/2017 57

58. Images Radio
09/05/2017 58

59. 4.5 Exemples 1soudures
Cracking can be detected in a radiograph only the crack is
propagating in a direction that produced a change in thickness that
is parallel to the x-ray beam. Cracks will appear as jagged and
often very faint irregular lines. Cracks can sometimes appearing as
"tails" on inclusions or porosity.09/05/2017 59

60. Burn through (icicles) results when too much heat causes
excessive weld metal to penetrate the weld zone. Lumps of
metal sag through the weld creating a thick globular condition
on the back of the weld. On a radiograph, burn through
appears as dark spots surrounded by light globular areas.09/05/2017 60
4.5 Exemples 2 soudures

61. Gas porosity or blow holes
are caused by accumulated
gas or air which is trapped by
the metal. These
discontinuities are usually
smooth-walled rounded
cavities of a spherical,
elongated or flattened shape.
Sand inclusions and dross
are nonmetallic oxides,
appearing on the radiograph
as irregular, dark blotches.
09/05/2017 61

62. 4.6 Limitations of Radiography
• There is an upper limit of thickness through
which the radiation can penetrate, e.g. γ-ray
from Co-60 can penetrate up to 150mm of steel
• The operator must have access to both sides of
an object
• Highly skilled operator is required because of
the potential health hazard of the energetic
radiations
• Relative expensive equipment
09/05/2017 62

63. 09/05/2017 63

64. 5. Ultrasonic Testing
The most commonly used
ultrasonic testing technique is
pulse echo, whereby sound is
introduced into a test object and
reflections (echoes) from internal
imperfections or the part's
geometrical surfaces are returned
to a receiver. The time interval
between the transmission and
reception of pulses give clues to
the internal structure of the
material.
In ultrasonic testing, high-frequency sound
waves are transmitted into a material to
detect imperfections or to locate changes
in material properties.
5.1 Introduction
09/05/2017 64

65. High frequency sound waves are introduced into a
material and they are reflected back from surfaces or
flaws.
Reflected sound energy is displayed versus time, and
inspector can visualize a cross section of the specimen
showing the depth of features that reflect sound.
f
plate
crack
0 2 4 6 8 10
initial
pulse
crack
echo
back surface
echo
Oscilloscope, or flaw
detector screen
Ultrasonic Inspection (Pulse-Echo)
09/05/2017 65

66. Generation of Ultrasonic Waves
• Piezoelectric transducers are used for
converting electrical pulses to
mechanical vibrations and vice versa
• Commonly used piezoelectric materials
are quartz, Li2SO4, and polarized
ceramics such as BaTiO3 and PbZrO3.
• Usually the transducers generate
ultrasonic waves with frequencies in the
range 2.25 to 5.0 MHz
09/05/2017 66

67. Ultrasons Propagation ,types ondes
• Ondes
longitudinale de
compression
• Ondes de
cisaillement or
transversales
• Ondes de surface
ou Rayleigh
09/05/2017 67

68. • Longitudinal waves
– Similar to audible sound
waves
– the only type of wave
which can travel through
liquid
• Shear waves
– generated by passing the
ultrasonic beam through
the material at an angle
– Usually a plastic wedge is
used to couple the
transducer to the material
09/05/2017 68

69. 09/05/2017 69

70. Characteristics of Piezoelectric Transducers
• Immersion: do not contact the
component. These transducers
are designed to operate in a
liquid environment and all
connections are watertight.
Wheel and squirter transducers
are examples of such immersion
applications.
Transducers are classified into groups according to the application.
Contact type
• Contact: are used for direct
contact inspections. Coupling
materials of water, grease, oils, or
commercial materials are used to
smooth rough surfaces and
prevent an air gap between the
transducer and the component
inspected.
immersion
09/05/2017 70

71. • Dual Element: contain two independently
operating elements in a single housing.
One of the elements transmits and the
other receives. Dual element transducers
are very useful when making thickness
measurements of thin materials and when
inspecting for near surface defects.
Dual element
• Angle Beam: and wedges are typically
used to introduce a refracted shear wave
into the test material. Transducers can be
purchased in a variety of fixed angles or in
adjustable versions where the user
determines the angles of incident and
refraction. They are used to generate
surface waves for use in detecting defects
on the surface of a component.
Angle beam09/05/2017 71

72. 09/05/2017 72

73. Ondes de Surface
• Un angle incident
qui fait refracter
angle de sortie à
90°
• Surface are
influencées par les
defauts pres de la
surface
• parcours le long de
courbes avec peu
de reflexion
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74. 09/05/2017 74

75. 09/05/2017 75

76. 5.2 Presentation données
Ultrasonic data can be collected and displayed
in a number of different formats. The three most
common formats are know in the NDT world as
A-scan, B-scan and C-scan presentations.
Each presentation mode provides a different
way of looking at and evaluating the region of
material being inspected. Modern computerized
ultrasonic scanning systems can display data in
all three presentation forms simultaneously
09/05/2017 76

77. 5.4.1 A-Scan
The A-scan presentation displays the amount of received
ultrasonic energy as a function of time. The relative amount of
received energy is plotted along the vertical axis and elapsed
time (which may be related to the sound energy travel time
within the material) is display along the horizontal axis.
Relative discontinuity size
can be estimated by
comparing the signal
amplitude obtained from an
unknown reflector to that
from a known reflector.
Reflector depth can be
determined by the position
of the signal on the
horizontal sweep.09/05/2017 77

78. The B-scan presentations is a profile (cross-sectional) view of the a
test specimen. In the B-scan, the time-of-flight (travel time) of the
sound energy is displayed along the vertical and the linear position of
the transducer is displayed along the horizontal axis. From the B-
scan, the depth of the reflector and its approximate linear dimensions
in the scan direction can be determined.
5.4.2 B-Scan
The B-scan is typically
produced by establishing a
trigger gate on the A-scan.
Whenever the signal intensity
is great enough to trigger the
gate, a point is produced on
the B-scan. The gate is
triggered by the sound
reflecting from the backwall
of the specimen and by
smaller reflectors within the
material.
09/05/2017 78

79. 5.4.3 C-Scan:
The C-scan presentation provides a plan-type view of the location
and size of test specimen features. The plane of the image is parallel
to the scan pattern of the transducer.
C-scan presentations are produced with an
automated data acquisition system, such as a
computer controlled immersion scanning
system. Typically, a data collection gate is
established on the A-scan and the amplitude
or the time-of-flight of the signal is recorded
at regular intervals as the transducer is
scanned over the test piece. The relative
signal amplitude or the time-of-flight is
displayed as a shade of gray or a color for
each of the positions where data was
recorded. The C-scan presentation provides
an image of the features that reflect and
scatter the sound within and on the surfaces
of the test piece.
09/05/2017 79

80. • Eddy current testing can be used on all electrically conducting
materials with a reasonably smooth surface.
• The test equipment consists of a generator (AC power supply), a
test coil and recording equipment, e.g. a galvanometer or an
oscilloscope
• Used for crack detection, material thickness measurement
(corrosion detection), sorting materials, coating thickness
measurement, metal detection, etc.
6. Eddy Current Testing
Electrical currents are generated in a conductive material by an
induced alternating magnetic field. The electrical currents are
called eddy currents because the flow in circles at and just
below the surface of the material. Interruptions in the flow of
eddy currents, caused by imperfections, dimensional changes,
or changes in the material's conductive and permeability
properties, can be detected with the proper equipment.
09/05/2017 80

81. 6.1 Principle of Eddy Current Testing (I)
• When a AC passes through a
test coil, a primary magnetic
field is set up around the coil
• The AC primary field induces
eddy current in the test object
held below the test coil
• A secondary magnetic field
arises due to the eddy current
09/05/2017 81

82. Conductive
material
Coil
Coil's
magnetic field
Eddy
currents
Eddy current's
magnetic field
6.2 Eddy Current Instruments
Voltmeter
09/05/2017 82

83. • The strength of the
secondary field depends on
electrical and magnetic
properties, structural
integrity, etc., of the test
object
• If cracks or other
inhomogeneities are
present, the eddy current,
and hence the secondary
field is affected.
Principle of Eddy Current Testing (II)
09/05/2017 83

84. 09/05/2017 84

85. • The changes in the secondary
field will be a ‘feedback’ to the
primary coil and affect the
primary current.
• The variations of the primary
current can be easily
detected by a simple circuit
which is zeroed properly
beforehand
Principle of Eddy Current Testing (III)
09/05/2017 85

86. Eddy currents are closed loops of induced current circulating in planes
perpendicular to the magnetic flux. They normally travel parallel to the
coil's winding and flow is limited to the area of the inducing magnetic field.
Eddy currents concentrate near the surface adjacent to an excitation coil
and their strength decreases with distance from the coil as shown in the
image. Eddy current density decreases exponentially with depth. This
phenomenon is known as the skin effect.
Profondeur de Penetration
The depth at which eddy current density has decreased to 1/e, or about 37%
of the surface density, is called the standard depth of penetration (δ).09/05/2017 86

87. Effet de peau
09/05/2017 87

88. 6.3 Resultats
The impedance plane
diagram is a very useful
way of displaying eddy
current data. The strength
of the eddy currents and
the magnetic permeability
of the test material cause
the eddy current signal on
the impedance plane to
react in a variety of
different ways.
09/05/2017 88

89. 3 Types Majeur de sonde CF
• configurations
– Surface
– bobine interne
– sonde encerclante
09/05/2017 89

90. Applications with Internal
Bobbin Probes
09/05/2017 90

91. •Crack Detection
•Material Thickness
Measurements
•Coating Thickness
Measurements
•Conductivity Measurements For:
•Material Identification
•Heat Damage Detection
•Case Depth Determination
•Heat Treatment Monitoring
6.4 Applications
09/05/2017 91

92. •Sensitive to small cracks and other defects
•Detects surface and near surface defects
•Inspection gives immediate results
•Equipment is very portable
•Method can be used for much more than flaw detection
•Minimum part preparation is required
•Test probe does not need to contact the part
•Inspects complex shapes and sizes of conductive
materials
6.5 Advantages of ET
09/05/2017 92

93. •Only conductive materials can be inspected
•Surface must be accessible to the probe
•Skill and training required is more extensive than other
techniques
•Surface finish and and roughness may interfere
•Reference standards needed for setup
•Depth of penetration is limited
•Flaws such as delaminations that lie parallel to the
probe coil winding and probe scan direction are
undetectable
Limitations of ET
09/05/2017 93

94. 7. Emission Acoustique
09/05/2017 94

95. 09/05/2017 95

96. 09/05/2017 96

97. 09/05/2017 97

98. 8. Test d’etancheité
09/05/2017 98

99. 09/05/2017 99

100. 09/05/2017 100

101. 9. Thermographie infrarouge
09/05/2017 101

102. 09/05/2017 102

103. 09/05/2017 103

104. 10 Protection cathodique
09/05/2017 104

105. 11. Applications NDT
• Inspection of matieres
premieres
• Inspection transformation
Processus
• Expertise en Service /
Inspection des dommages
09/05/2017 105

106. Inspection of Raw Products
• Forgings,
• Castings,
• Extrusions,
• etc.
09/05/2017 106

107. • Machining
• Welding
• Grinding
• Heat treating
• Plating
• etc.
Inspection Following
Secondary Processing
09/05/2017 107

108. • Cracking
• Corrosion
• Erosion/Wear
• Heat Damage
• etc.
Inspection For
In-Service Damage
09/05/2017 108

109. Power Plant Inspection
Probe
Signals produced
by various
amounts of
corrosion
thinning.
Periodically, power plants are
shutdown for inspection.
Inspectors feed eddy current
probes into heat exchanger
tubes to check for corrosion
damage.
Pipe with damage
09/05/2017 109

110. Wire Rope Inspection
Electromagnetic devices
and visual inspections are
used to find broken wires
and other damage to the
wire rope that is used in
chairlifts, cranes and other
lifting devices.
09/05/2017 110

111. Storage Tank Inspection
Robotic crawlers
use ultrasound to
inspect the walls of
large above ground
tanks for signs of
thinning due to
corrosion.
Cameras on
long
articulating
arms are used
to inspect
underground
storage tanks
for damage.
09/05/2017 111

112. Aircraft Inspection
• Nondestructive testing is used
extensively during the
manufacturing of aircraft.
• NDT is also used to find cracks
and corrosion damage during
operation of the aircraft.
• A fatigue crack that started at
the site of a lightning strike is
shown below.
09/05/2017 112

113. Jet Engine Inspection
• Aircraft engines are overhauled
after being in service for a period
of time.
• They are completely disassembled,
cleaned, inspected and then
reassembled.
• Fluorescent penetrant inspection
is used to check many of the parts
for cracking.
09/05/2017 113

114. Sioux City, Iowa, July 19, 1989
A defect that went
undetected in an
engine disk was
responsible for
the crash of
United Flight 232.
Crash of United Flight 232
09/05/2017 114

115. Pressure Vessel Inspection
The failure of a pressure vessel
can result in the rapid release of
a large amount of energy. To
protect against this dangerous
event, the tanks are inspected
using radiography and
ultrasonic testing.
09/05/2017 115

116. Rail Inspection
Special cars are used to
inspect thousands of miles
of rail to find cracks that
could lead to a derailment.
09/05/2017 116

117. Bridge Inspection
• The US has 578,000
highway bridges.
• Corrosion, cracking and
other damage can all
affect a bridge’s
performance.
• The collapse of the Silver
Bridge in 1967 resulted in
loss of 47 lives.
• Bridges get a visual
inspection about every 2
years.
• Some bridges are fitted
with acoustic emission
sensors that “listen” for
sounds of cracks growing.
09/05/2017 117

118. NDT is used to inspect pipelines
to prevent leaks that could
damage the environment. Visual
inspection, radiography and
electromagnetic testing are some
of the NDT methods used.
Remote visual inspection using
a robotic crawler.
Radiography of weld joints.
Magnetic flux leakage inspection.
This device, known as a pig, is
placed in the pipeline and collects
data on the condition of the pipe as it
is pushed along by whatever is being
transported.
Pipeline Inspection
09/05/2017 118

119. Special Measurements
Boeing employees in Philadelphia were given the privilege
of evaluating the Liberty Bell for damage using NDT
techniques. Eddy current methods were used to measure
the electrical conductivity of the Bell's bronze casing at a
various points to evaluate its uniformity.
09/05/2017 119