NDT HANDBOOK

Non-Destructive Testing
Inspector's
'v
Handbook
Visual Inspection (VT)
Liquid Penetrant Inspection (PT)
Magnetic Particle Testing (MT)
Ultrasonic Testing (UT)
Eddy Current Testing (ET)
RadiographicInspection (RT)

Preface
This referencebook was designed for use in the field and to support onthe-jobtraining. It should not be
Lised as a standardor referred to as a stand-alone document. This book covers basic formulas,charts, and other
NDT related information.
Dedication
To allthe people who have influencedmy naval career and where I am today in the NonDestructive field.
Thank you. I originally startedthis project as a self-knowledgeapplication and began receiving commentsfrom my
fellow colleagues requesting a copy. I soon realized that this would prove to be an invaluabletool for general
infomation in our field. I have received support from both military and civilian personnel and have taken a sample
of their suggestionsand compiled them for you, the end user. I wanted to take personal credit for this project and
realized it would not benefit the NDT field as a whole. Instead, I encourage you, the end user, to change,
manipulate, or configurethis book for yourself. In closing, "Share the Wealth with Others."
Last Revision Date
20 April 2002
Contact Information
Keoke526@hotmail.com
ndthandbook.zapto.org
Disclaimer
Thisbook is not intended for sale or any monetary benefit to the editor.
Inspector's Handbook

Table of Contents
Scope of Standards..............................................................................................................................................iv. .
.................................................................Chapter 1- General Information I d
..............................................................................................................ScheduleDesignationsof Pipe Sizes
.Copper Tubing Wall Thickness.....................................................................................................................1 1
...........................................................................................................................................Decimal to Inches 1 1
.............................................................................................................................TemperatureConversions -1 1
Fraction to Decimal Equivalent..................................................................................................................1-2
Decimal to Second Conversion.....................................................................................................................1-2
......................................................................................................................Numerical Place Value Chart 1 - 2
Elements of a Nondestructive Examination Symbol....................................................................................1-3
Elements of a Welding SyrnboL....................................................................................................................1-3
....................................................................................................................................Examples of Grooves 1-4
..................................................................................................................................Basic Joints (Welding) 1-4
.................................................................................................Order ofPerformingArithmetic Operations 1-5
....................................................................................................................................Ratio And Proportion 1-6
....................................................................................................................................Calculationof Area 1 - 7
Weld Area Calculation..................................................................................................................................1-7
.......................................................................................................................Common Symbolsand Terms 1-7
...............................................................................................................Solutionof Right-angled Triangles 1-9
................................................................................................................... .Basic Illustration of a Weld 1 10
.......................................................................................................................................WeldingProcesses - 11
.................................................................................................. .Backing Ring Common Defect Locations 1 12
.......................................................................................... .Consumable Insert Common Defect Locations 1 12
............................................................................................................Primary ProcessingDiscontinuities 4
Finish Processing Discontinuities................................................................................................................
..............................................................................................................................Dial Indicating Calipers 1-15
...............................................................................................................................................Micrometer 1 -15
.................................................................................................................Thread Terminology (fasteners) 1 -16
.............................................................................................................................Tap and Drill Size Chart: 1-16
.................................................................................................................Julian Date Calendar (Perpetual) 1-17
..............................................................................................................JulianDate Calendarp a p Year) -1-18
Chapter 2 .Visual Inspection......................................................................2-1
...........................................................................................................Common Definitionsand Examples 2 - 1
Chapter 3 .Liquid Penetrant Testing..........................................................3-1
Common Terms and Definitions..................................................................................................................-3-1
Prorated Maximum Number of Indications ..................................................................................................3-6
Areas of Circles.............................................................................................................................................3-6
Penetrant Wetting Characteristics.................................................................................................................3-7
Chapter 4 .Magnetic Particle Testing.........................................................4-1
.............................................................................................................CommonDefinitionsand Examples 4. 1
..................................................................................................LongitudinalMagnetizationMath Formula 4F7
..................................................................................................Prorated MaximumNumber of Indications -.............................................................................................................................................Areas of Circles 4
CommonTypes of Magnetization................................................................................................................4-9
Inspector's H m m k

..........................................................................................................................Theory: "RigheHand Rule -4-9
........................................................................................................................................Hysteresis=Curve -4-10
..............................................................................................Magnetic ParticleField Indicator(Pie Gage) 4- 11
. ....................................................................* & Chapter 5 Ultrasonic Testing 5-1
...................................................................................................................Common Terms and Definitions 5-1
............................................................................................................................CommonMath Formulas 5-12
.............................................................................................................Calibration Chart.UT Shearwave 5- 13
FPADSCRhD..............................................................................................................................................5-14
.............................................................................................................................................Velocity Chart 5-15
Chapter 6 .Eddy Current Testing ...............................................................6-1
...................................................................................................................Common Terms and Definitions - 1
Two Types of Electrical Current ...................................................................................................................6-6
Conductivity and the IACS...........................................................................................................................6-7
Right Hand Rule............................................................................................................................................6-7
Magnetic Domains ........................................................................................................................................6-9
Depth of Penetration................................................................................................................................... 6-12
Limitations of Eddy Current Testing .........................................................................................................6-18
Advantagesof Eddy Current Testing...................................................................................................... 6 18
Summaryof Properties of Eddy Currents ...................................................................................................6-18
Eddy Current Relationshipof Properties ............................................................................................6 - 18
...........................................................Chapter 7 .Radiographic Inspection 7-1
Common Definitions and Examples ............................................................................................................-7-1
..........................................................................................................Structureof the Atom and an Element 7-8
.............................................................................................................................Componentsof an Isotope 7-8
Characteristics of A Radioactive Element .................................................................................................... 7-8
Two Types of Radiation................................................................................................................................7-8
History of Radiography.................................................................................................................................7-9
60' Coverage for Pipes and Location Marker Measurements....................................................................7-11
Common Math Formulas ....................................................................................................................... 7 12
Magic Circles .......................................................................................................................................7 1 5
SingleWall Exposure I Single Wall Viewing for Plate ...........................................................................7-15
SingleWall Exposure1SingleWall Viewing for Pipe.............................................................................7-16
Double Wall Exposure 1Double Wall View (superimposed)...................................................................7-16
Double Wall ExposureI Double Wall View (offset) .............................................................................7-17
Double Wall Exposure 1SingleWall View ...............................................................................................7-17
KILLER CARL...........................................................................................................................................7-18
Penetrameter Material and GroupNumbers..............................................................................................7-18
Penny T-Hole Maximum Density.....................................................................................................7 19
2% PenetrameterQuality ConversionChart (X-RAY ONLY)...................................................................7-20
Basic Componentsof an X-ray Tube..........................................................................................................7-25
Types of ScatterRadiation.......................................................................................................................... 7-25
. .Radiographc Fllm Interpretation................................................................................................................7-25
. . ................................................................................................................Radiographic Film Interpretation 7-26
...................................................Probable Causes and CorrectiveAction for Automatic Film Processing 7-50
................................................Probable Causes and CorrectiveAction for Processed RadiographicFilm 7-51
Inspector's Handbook iii

Scope of Standards ..
NSTP 271 REQUIREMENTSFOR NONDESTRUCTIVETESTINGMETHODS - -
This document covers the requirements for conducting nondestructivetests (NDT) used in detenninin(
presence of surface and internal discontinuities in metals. It also containsthe -mum requirements necessary .qualifLnondestructivetest and inspection personnel, procedures, and nondestructiveequipment. This document
does not contain acceptancecriteria for nondestructivetest. This document does not cover all of the requirements
for performing nondestructivetests in an underwater environment.Nondestructivetests in an underwater
environment shallbe performed as specified in NAVSEA S0600-AA-PRO-070.
NSTP 248 REQUIREMENTS FOR WELDING AND BRAZING PROCEDURE AND PERFORMANCE
QUALIFICATION
This document contains the requirements for the qualificationof welding and brazing procedures, welders,
welding operators,brazers and brazing operators that must be met prior to any production fabrication. It includes
manual, semiautomatic,automatic and machine welding and brazing of ferrous, nonferrous, and dissimilarmetals.
The qualificationtests required by this document are devisedto demonstratethe adequacy of the welding or
brazing procedures and to demonstratethe abilityof welders, brazers, welding operatorsand brazing operatorsto
produce soundwelds orbrazes.
NSTP 278 REQUIREMENTSFOR FABRICATIONWELDING AND INSPECTION,AND CASTING
INSPECTIONAND REPAIR FOR MACHINERY,PIPING, AND PRESSUREVESSELS
Thisdocumentcontainsthe welding and alliedprocesses (exceptbrazing) and casting requirements
including inspection for the fabrication,alteration, or repair of any item or component of machinery, piping, and
pressure vessels in ships of the United StatesNavy.
MILSTD 2035 NONDESTRUCTIVE TESTING ACCEPTANCE CRITERIA
The acceptance criteriacontainedherein are for use in determining the acceptability of nondestructive t. -(NDT)discontinuitiesin castings,welds, forgings, extrusions, cladding, and other productswhen specifiedby the
applicableNaval Sea Systems Command (NAVSEA)drawing, specification, contract, order, or directive.
NSTP 1688FABRICATION,WELDING AND INSPECTION SUBMARINEAPPLICATIONS
This document containsminimum requirements for fabrication and inspectionof submarineand non
combatant submersiblestructures, including shipbuildingpractices, specificationsfor materials, weldjoint design,
workmanship,welding, inspection, and record requirements.
MILSTD 1689FABRICATION,WELDING, AND INSPECTION OF SHIPSSTRUCTURE
This standard contains the minimum requiremeas for the fabrication and inspection of the hull and
associated structures of combatant surface ships. The requirements for shipbuilding,materials, welding, welding
design, mechanicalfasteners, workmanship, inspection, forming, castings and records are included. It also applies
to those submarine structureswhich are not high-yield strengthsteels.
MILSTD 22DWELDED JOINT DESIGN
This standard covers welded joint designs for manual, semi-automatic, and automatic arc and gaswelding
processes for use onmetalsand weldments, as applicable, when invoked by a fabricationdocument. The welded
joint designs shownherein represent standardjoint designsused in welded fabrication and are not intendedto be
all inclusive.

NSTP CHAPTER 074-VOLUME 1WELDING AND ALLIED PROCESSES
This chapter furnishesboth the minimum mandatory requirements (indicatedby the word shall) and
guidance information (indicatedby the words should or may) necessary for welding, brazing, inspection, and
safetywhen used for ship maintenance, repair, and alteration.
-NSTP CHAPTER074-VOLUME 2 NONDESTRUCTIVE TESTING OF METALS QUALIFICATION
AND CERTIFICATION REQUIREMENTS FOR NAVAL PERSONNEL (NON-NUCLEAR)
This chapter is M s h e d to ensure achievementof uniform and reliable nondestructivetests on naval
materialsand components,implementationof the training, qualification, and certificationprograms described in
this chapter shouldbe followedprecisely.

Decimal to Inches
inches 112 = decimal
decimal 12 = inches
Temperature Conversions-
Fahrenheit= (915 * C) +32
Celsius=(F- 32) * 519
Copper TubingWall Thickness

Fraction to Decimal Eauivalent 1 I Decimal to Second Conversion I
I PLACE) I
Numerical Place Value ChartI
F o r E x a m p l e 2 , 2 6 2 . 3 5 7 . 6 1 9 8 4 4
2
THOUSANDS
bI UNITS I 1 ILI
2
3
5
MILLIONS
100,MK)
TEN
THOUSANDS
THOUSANDS
HUNDREDS
TENS
1,000,000
E
10,000
1,000
loo
10
D
1
C
1
A
6
HUNDREDTHS
9
8
4
TENTHS
I
1/10 I 0.1
1/100
THOUSANDTHS
TEN
THOUSANDTHS
HUNDRED TEN
THOUSANDTHS
MILLIONTHS
0.01
111,000
1110,000
1H00.000
111,000,000
0.001
0.0001
0.00001
0.000001

Elements of a NondestructiveExamination Symbol
Elements of a Welding Symbol
NUMBER OF EXAMINATIONS LENGTH OF SECTION TO BE
EXAMINED
REFERENCE LINE
-EXAMINE IN FIELD
SPECIFICATION OR OTHER
REFERENCE EXAMINE-ALL-AROUND
TAIL ARROW
GROOVE ANGLE: INCLUDED ANGLE OF
FINISH SYMBOL COUNTERSINK FOR PLUG WELDS
ROOT 0PENING:DEPTH OF FILLING FOR PLUG
GROOVE WELD SIZE AND SLOT WELDS
DEPTH OF BEVEL; SIZE OR STRENGTH FOR LENGTH OF WELD
CERTAIN WELDS PITCH OF WELDS
-FIELD WELD
SPECIFICATIONOR OTHER
NOT USED)
REFERENCE (OMITTEDWHEN T WELD-ALL-AROUND
TAIL ARROW
NUMBER OF SPOT, SEAM, STUD,
PLUG. OR PROJECTION WELDSA
RADIATION DIRECTIONEXAMINE ALL AROUND
Plugor Spot or Back or Flange
Fillet Slot Stud Projetiin Seam Backing Surfacrng Edge 1 Corner
FIELD EXAMINATION
/
L
GROOVE
Basic Weld Symbols
Square
--LL--- -
i
Scad
--.
-7r-
Weld all
around
V
-v---A-
FieldWeld
/--
i
Mvel
- --1'T--
Melt
~hrough
-Tee
U
--Y----A--
Consumable
Insen
(Square)
J
--Y----K-
Backing
or Spacer
(Recrangle)
Flare-V
-I/_-
-2x--
,Contour
Flare-
bevel
--LC-
--rc-
Flush
or Flat Convex Concave

Examples of Grooves
square SingleJ Single Bevel
SingleVee Double Bevel SingleU
Basic Joints (Welding) I
I Lav
' / I corner / /
w e Tee

Order of PerformingArithmetic Operations
When severalnumbers or quantitiesin a formula are connected by signs indicatingthat additions,
subtractions,multiplications, or divisions are to be made, the multiplicationsand divisions should be carried out
1,%st, in the order in which they appear,before the additions or subtractionsare performed.
Examples: 10+26X7-2=10+182-2=190
18+6+15X3=3+45=48
12+14+2-4=12+7-4=15
When it is required that certain additions and subtractionsshouldprecede multiplication's and divisions,use
is made of parentheses 0 and brackets n.
These indicatethat the calculation inside the parentheses or brackets shouldbe carriedout completeby itself
before the remaining calculations are commenced. If one bracket is placed inside of another, the one inside is first
calculated.
Examples: (6-2)X5+8=4X5+8=20+8=28
6X(4+7)+22=6X 11-22=66+22=3
2+[1OX6(8+2)-4]X2=2+[1OX6Xl0-4]X2
=2+[600-4]X2=2+596X2=2+1192=1194
The parentheses are consideredas a sign of multiplication;for example, 6(8 +2) = 6 x (8 +2).
The line or bar between the numeratorand denominatorin a fractionalexpressionis to be consideredas a
division sign. For Example,
In formulasthe multiplicationsign(X) is often left out between symbolsor letters, the values of which are to be
multiplied. Thus
ABC
AB=AXB,and-= (AXBXC)+D
D

Ratio And Proportion
The ratio between two quantitiesis the quotient obtainedby dividingthe first quantityby the second. For
example, the ration between 3 and 12is '14, and the ratiobetween 12and 3 is 4. Ratio is generallyindicatedP - *
sign (:); thus 12 :3 indicatesthe ratio of 12to 3. d
A reciprocal or inverseratio is the reciprocalor the original ratio. Thus, the inverseratio 5 :7 is 7 :5.
In a compound ratio each term is the product of the correspondingterms in two or more simpleratios.
Thus when
then the compound ratio is:
Prop is the equality of ratios. Thus,
The firstand last tenns in a proportion are called the extremes;the second and thirds, the means. The
product of the extremesis equalto the product of the means. Thus,
If third terms in the proportion are known, the remaining term may be found by the followingrules:
1)The firstterm is equalto the product of the secondand third terms, dividedby the fourth term.
2) The second term is equal to the product of the first and fourth terms, divided by the third.
3) The third term is equal to the product of the first and fourth terms, dividedby the second.
4) The fourthterm is equalto the product of the second and third tenns, dividedby the first.

Calculationof Area
Square/Rectangle = Length * Width
Circles -- w2
Triangle = Height * Base * 1/2
Sphere -- 4m2
Weld Area Calculation
Structural Welds = Length * Width (measured)
Piping Welds = Circumference(OD*7t) * Width
Socket Welds = L x W
L = ((OD at A + OD at B) / 2) *7t
W = Width of the weld is measured.
Common Symbols and Terms
3.1415
Diameter / 2
Inside Diameter
Outside Diameter
Less Than (ie 6 ~ 9 )
Greater Than (ie 9>6)
Equal To or Less Than
Equal To or Greater Than
Plus or Minus
InspectaPs Handbook

Change percent ( % ) to decimal (0.0).
Move decimal point 2 spaces to the left and drop the percent sign.,
Example: 2% = 2.0% = -02 d
Change decimal (0.0) to percent ( % ) . ..
Move decimal point 2 units to the right and add the percent sign.
Example: .43 = 43%
Change a fraction to a decimal.
Divide the numerator by the denominator.
Example: 1/2 = 1 divided by 2 = .5
Tm = Material Thickness, thickness of the thinner member
excluding reinforcements.
Ts = Specimen Thickness, thickness of the thinner member
including reinforcements.
Minimum Weld Throat Thickness = .7 x Tm
Based upon 1T X 1T

Solutionof Right-angled Triangles

Basic Illustrationof a Weld
FILLET LEG
SIZE OF WEW
1qxctoP"sHandbook

Welding Processes ha
ELECTRODE COVERING
Shielded Metal Arc Welding (SMAW)
An arc weldingprocess, which melts and
b,ins metals by heating them with an arc
oetween a covered metal electrode and the
work. Shielding gas is obtained fromthe
electrodeouter coating, often called flux. METALAND SLAG
Commonly referred to as "stick" welding. SOLIDIFIEL)SLAG
SHELDINGGASIN ON
WELD
CURRENT CONDUCTOR
WIRE GUIDE
DIRECTION AND CONTACT
Gas Metal Arc Welding (GMAW)
OFWELDING An arc welding process, whichjoins metals by heatingthem
GAS NOZZLE with an arc. The arc is between a continuously-fedfiller metal
(consumable) electrodeand the mrk piece. Shieldinggas is
supplied from an external source of inert gas, normally argon,
helium, or a mixture of the two. Commonlyreferred to as
"MIG" welding.
joins metalsby heatingthem with an arc
WIRE GUIDE 6. between a continuous,consumableelectrode
CONTACTTUBE wire and the work Shielding is obtained from a
flux containedwithin the electrode core.
Depending upon the type of flux-cored wire,
added shieldingmay or may not be provided
from externallysuppliedgas or gas mixture.
tungsten electrode, which shouldnot become part of the
L
*ompletedweld. Filler metal is normally used when welding.
Jsually helium or argon, or mixture, is used for shielding gas.
Inspector's Handbook 1-1 1

Backing Ring Common Defect Locations
CRACKING
OVERLAP SLAG/OXIDEINCLUSIONS i

u
UNDERCUT TUNGSTEN INCLUSIONS
POROSITY INCOMPLETE (LACK OF) FUSION
I CRACKING
BURN-THROUGH
ConsumableInsert CommonDefect Locations
/
INCOMPLETE (LACK OF) PENETRATION
SLAGOR UNDERCUTAT THE ROOT
TOES
CRACKING
OVERLAP SLAG/OXIDEINCLUSIONS
UNDERCU
INcLuSroNS INCOMPLETE (LACK OF) FUSION
POROSITY
I CRACKING
BAD FITUP
SLAGBETWEEN BACKING
RING AND PIPE ID
u
CONCAVITY MELT-THROUGH
BURN-THROUGH INCOMPLETE (LACK OF) FUSION 4
UNDERBEAD CRATERS CENTERLINE CREASE
OVERLAP CRACKING
UNDERCUT AT THE#OO&OTTO#
BACKING GAS LOS A% MPLETE (LACKOF) PENETMTION
CRACKING
MELT-THROUGH

Hot Tear
Primary Processing Discontinuities
IDifference in cooling rates between thin sections
and thick sections
1 surface
I
Location
Surface
Caused By
Lack of h i o n between two interceptingsurfaces
of metal as it flows into the cast
Process
:L
Casting
I Porosity
IEntrapped internal gasses
Discontinuity
Cold Shut
BlowHoles
Cavity
Microshrinkage
Inability of external gassesto escape h m the
mold
Forging
I
IFlatteningand lengtheningof discontinuities
L sdgem (bar found in parent material
( Subsurface I
Lack of enough molten metal to fill the space
createdby shrinkage
Improperlydesigned mold causingpremature
blockage at the mold gate
Surface
I Laminations(flatplate)
Lengthening of surfacecracks found in parent I Surface
I
Subsurface
Subsurface
Lap
Burst
Flatteningand lengtheningof discontinuitiesin
parent material I Subsurface (
F r I L a C k o f Fusion IIncomplete weld I Surface
(inner and outer)
Folding of metal in a thin plate on the surface of
the forging
Forging at impropertemperature
Surface
Surfaceor
Subsurface
Seams
pipe
IPresent in the parent material (roundbar stock)
Laminations
Gouges
Seamless
Pipes and
Tubes
ISizing mandrel dragging
Present in the parent material (sheet or parent
material)
1- Seams
Subsurface
Slugs
Present in parent material ( Surface 1
Porosity ( Present in parent material
,
Metal buildup on piercingmaterial
Inner
Surface
Inspector's Handbook 1-13
I
I
w
1
Galling (cracks) Impropermetal flow through the die Surface

I Heat Treating
FinishProcessing Discontinuities
Explosive
Forming
Process
Grinding
Welding
StressCracks
Discontinuity
Cracks
Cracks and Tears
Crater Cracks (star,
transverse,and
longitudinal)
Caused By
Excess localized heat created between the
grinding wheel and the material
StressCracks
Location
Surface .-/
- -
Porosity
Slag Inclusions
TungstenInclusions
I
Lack of Penetration
Lack of Fusion
Undercut
Overlapping
I
Extreme deformationoverstresses the material I surface
I
~ -
Stressbuilt up by improper processing-unequal
heating and cooling
Improper use of heat source
Surface
Surfaceor
I Subsurface I
Entrapped gasses
Stressesbuilt up by the weld contraction(if
material is restrained)
Surfaceor
I Subsurface
Surface
Excessive current used during GTAW
Incomplete cleaningof slag fiomthe weld
betweenpasses
I Subsurface I
Surfaceor
Subsurface
Improper welding technique Surfaceor
I Subsurface I
Improperwelding technique Subsurface 1
Improperwelding technique I surface (
Weld overlapsparent material -not b e d I surface
I
I Bending Cracks
I
- -
Overstress of material
I Machining 1 Tears IWorkingwith dull tools or cutting too deep 1 Surface
I
I Pz?,"I Cracks
1 Electroplating
I Cracks
Inspector's Harrdbook
Relief of internal stress
Relief of internal stress
Surface
Surface

Dial IndicatingCalipers
1.VerifLthe caliper's calibration date is current, and clean all dirt fiom measuring faces. Performuser
calibration ondial indicator, ensure reading is zero, and tightenthe bezel clamp as needed.
2. Adjust measuring faces, contactpoints, to fit item being measured.
3. Apply f m pressure to fine adjustingroll and ensure measuringcontacts are in contact with the material
being measured.
4. Apply lock screw and read measurement in place if practical. If not, remove caliperscarefullyto prevent
false measurements.
Micrometer
PART TO BE MEASURED
GRADUATIONS
TO BE READ
FRAME
READING LINE
1.Verifj.that the micrometer's
calibration date is current, and cleanall
dirt from measuringcontacts. VEPN~ER
C
.000/
G I R H R T / O N S
IS
2. Attach ball if measuringcurved
surfaces.
3. Adjust micrometerto fit the item s-L fCYrC
being measured, do not spin frame to -too 4%vo.Olb
GRRDVRT/O/YS
adjust the micrometer.
4. Slipthe micrometer overthe areato be measured by placingthe anvilf d y againstthe material and slowlyturn
the thimble clockwiseuntil spindle is firmly against the material. Then turn the ratchet three clicks to be sure equal
pressure is applied.
5. Take reading in place, or set the lockingnut and remove fiomthe item. Determinereading on scale and note
w
accordingly. Do not forget to minus the ball measurement if used.

AXIS
PITCH
DIAMETER
Tap and Drill Size Chart
7
THREAD
1 SIZE
CREST
R m

"w
L'
L
Day
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Dec
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
Nov
305
306
307
308
309
310
311
-312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
Oct
274
275
276
277
278
279
280
281-
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
Sep
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
(Perpetual)
Aug
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
July
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
Date Calendar
June
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
Julian
May
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
Apr
091
092
093
094
095
096
097
098
099
100
101
102
103
104
105
106
107
108
109
110
111
112
I13
114
115
116
117
118
119
120
Mar
060
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
Feb
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
Day
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
. 31
Jan
0 0 1
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031

1-18 Inspector's Handbook
Day
1
2
3
4
5
6
7
8
9
I 0
I 1
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Jan
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
Feb
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
060
Mar
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
Apr
092
093
094
095
096
097
098
099
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
Julian
May
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
Date Calendar
June
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
(Leap
July
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
Year)
Aug
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
Sep
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
Dec
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
Oct
275
276
277
278
279
280
281
282
283
284
285
2 8 6
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
Nov
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
i
C
1 *
2
3
4
5
6
7
8
9
I 0
I 1
12
13
14
15 '
l b ,
v
17
18
19
20
21
22
23
24
25
26
27
28
29
30
3 . 4

Chapter 2 -Visual Inspection
Common Definitions and Examples
r Aligned rounded indications
i/ Four or more indications in a line, where each is separated
fromthe adjacent indication by less then 1/16inch or D, whichever
is greater,where D is the major diameter of the larger of the adjacent
indication.
Arc strike
Any localized heat-effected zone or changein the contour of
the surfaceof the finished weld or adjacent base metal resulting from
m atc or heat generatedby the passage of electricalenergybetween
the surfaceof the finished weld or base metal and a current source,
such as welding electrodesor magnetic particle inspectionprods.
Burnthrou~h
A void or open hole that extends through a backing ring, strip, fused root, or adjacent base metal.
Burst
A rupture causedby forging at improper temperatures. Bursts may be either internal or externalto the
surface.
Cold shut
The result ofpouring metal over solidifiedmetal.
/
Trackor tear
+ A linear rupture of metal under stress.
Craterpit
An approximatelycircular surfacecondition exceeding into
the weld in an irregular manner caused by insufficient filler metal at
theweld stop.
Defect
One or more flawswhose aggregate; size, shape, orientation,
location, or properties do not meet the specified acceptancecriteria
and are rejectable.
Discontinuity
Any interruption in the normal physical structure or
configurationof a part, which will cause a detectable indicationor
signal when nondestmctively examined.
Evaluation
A review, following interpretationof the indicationsnoted, to determine whether they meet specified
cceptance criteria.
L

False indication
An indicationthat is interpretedto be causedby a condition other than a discontinuityor imperfection.
Heat checks
Fissures or tears in the weld heat affected zone of material containinglow meltingpoint.
Indicatic
I
ure of quality characteristicfrom its intended condition.
Ln
Zvidence of a discontinuitythat requires interpretationto determine its significance.
ete fusion I,ack of completefusion of someportion of the metal in a
Weldjolnt with adjacent metal. The adjacentmetal may be either
base metal or previously deposited weld metal, or consumable insert.
Incompletepenetration
Lack of penetration of the weld through the thickness of the
joint, or penetrationwhich is lessthanspecified.
Interpretation
The determination of whether indicationsare relevant,
nonrelevant, or false.
Lap (forginas)
Folding of metal on the surface of the forging, usually occ ' u
when some of the forgingmetal is squeezedout between the two dies.
Linear indication
An indication in whichthe lengthis equalto or
greaterthanthree times the width.
Melt through
A convexor concave irregularityon the surfaceof a backing ring or strip, fusedroot, or adjacentbase metal
resulting from fusion completely through a localized region but without developmentof a void or open hole.
Non-linear rounded indications
Indication whose length is less thanthree times its width.
Nonrelevant indications
An indicationthat is causedby a condition or type of discontinuitythat is not relevant.

Oxidation
A condition resulting from partial or completelack of inert gas shieldingof a surfacewhich is heated
ring weldingresulting in formation of oxide on the surface. This condition may range fiom slight oxidation
idenced by a multicolored or tightly adheringblack film to the extreme of a very rough surfacehaving a
crystalline appearance.
Porosity
Gas pockets or voids in weld metal or castings.
Quenchcrack
A crack formed as a result of the& stressesproducedby
rapid cooling fiom a high temperature.
Root surfaceconcavity
A depression on the root surfaceof a weld which may be due
to gravity, internalpurge, or shrinkage.
Root surface centerlinecrease or shrinkage
An intermittentor continuousperipheral centerline concavity formed on the root surface.
Root undercut
A groove in the internal surfaceof a base metal or backingring or strip alongthe edge of the root of the
weld.
Shrinkage
Void, or voids, that may occur in molten metal due to
contractionduring solidification.
s&
Non-metallic solidmaterial entrapped in the weld metal,
between weld metal and base metal, or in a casting.
Tungsten inclusion
Tungsten entrapped in the weld deposit.
Undercut
A groove melted into the base metal at the toe of the weld and left unfilled by weld metal.
Unfusedchaplet
A metal supportused in the castingprocess, which has not
fused with casting material.
Weld spatter
Metal particles which deposit on the surface of the weld or
adjacent base metal duringwelding and which do not form a part of
theweld.

Chapter 3 - Liquid Penetrant Testing
CommonTerms and Definitions
Alkaline
L Any solublemineral salt or mixtures of salt capable of neutralizing acids.
Angstrom Unit (A)
A unit of length equal to lo8cm and used to expresswavelengths of light; i.e., electromagneticradiation.
Background
The surfaceupon which an indication is viewed. It may be the natural surfaceof the test article or it may be
the developercoating on the surface. This background may containtraces of unremoved penetrant (fluorescentor
visible), which, if present, can interfere with the visibility of indications.
Background Fluorescence
Fluorescent residues observed overthe general surface of the test article duringfluorescent penetrant
E h
Term used colloquially to designate the liquid penetrant inspectionmaterials into which test articles are
immersed during inspectionprocess.
Black Li~ht
Light radiation in the near ultraviolet range of wavelengths (3200 to 4000 A), just shorterthan visible light.
Black Light Filter
L A filter that transmits black light while suppressingvisible light and hard ultravioletradiation with
wavelengths less than 3200 angstroms.
Bleedout
The action of the entrappedPenetrant in spreading out from surface discontinuitiesto form an indication.
Blotting
The action of the developerin soakingup the entrappedpenetrant from d a c e discontinuities to form an
indication.
CapillaryAction or Capillarity
The tendency of liquidsto penetrate or migrate into small openings such as cracks,pits, or fissures.
CarrierFluid (Vehicleor Medium)
A fluid in which liquid penetrant inspection materials are dissolved or suspended.
Clean
Free from interferingsolid or liquid contaminationon the d a c e .
ComparativeTest Block
An intentionally crackedmetalblock having two separatebut adjacent areas for the application of different
penetrants sothat a d<ect comparisonof their relative effeativeness canbe obtained. Can alsobe used to evaluate
?enetranttest techniques and test conditions.

Contact Emulsifier
An emulsifierthat begins emulsifyingpenetrant upon simple contact with the penetrant; usually oil-base
(Lipophilic).
Contrast w
The difference in visibility (brightness or coloration)between an indication and the surroundingsurface.
DarkAdaptation
The adjustment of the eyeswhen one passes from a bright to a darkened area.
Detergent Remover
A penetrant remover that is a solution of a detergent in water. Also Hydrophilic Emulsifjer.
Developer
A materialthat is applied to the test article surfaceafter excess penetrant has been removed and that is
designedto enhancethe penetrantbleedout to form indications. The developermay be a finepowder, a solution
that dries to a fine powder, or a suspension(in solvent, water, alcohol, etc.) that dries leavingan absorptive film on
the test surface.
DevelopingTime
The elapsedtime necessary for the applied developerto bring out indications from penetrant entrapments.
Also calledDevelopment Time.
Dragout
Thecanput or loss of penetrant materials as a result of their adherence to the articles being processed.
Drain Time w
That portion of the penetrant inspectionprocess duringwhich the excesspenetrant, emulsifier, detergent
remover, or developeris allowed to drain fiom the test article.
Dry Developer
A fine, dry powder developerthat does not employ a carrier fluid.
DryingOven
An oven used for drying test articles.
Drvinn Time
A time allottedfor a test articleto dry.
DuaLresponsePenetrant
A penetr- that contains a combinationof visible and fluorescentdyes.
Dwell Time
The total time that the penetrant or emulsifier is in contact with the test surface, includingthe time required
for application and the draintime. Also see EmulsificationTime.
ElectrostaticSpraying
A technique of spraying wherein the material being sprayed is given a high electrical charge while the test
axticle is grounded. u

Emulsification Time
The period of time that an emulsifieris permittedto combine with the penetrant prior to removal. Also
calledEmulsifierDwell Time.
Tmulsifier
'v
A liquid that combines with an oily penetrant to make the penetrant water-washable. Also seeHydmphilic
Emulsifier &d LipophilicEmulsifier.
Flash Point
The lowest temperature at whicha volatile, flammableliquid will give off enough vapor to make a
combustibleexplosivemixture in the air space surroundingthe liquid surface.
Fluorescence
The emissionof visible radiationby a substanceas a result of, and only during, the absorptionof black light
radiation.
Fluorescent Dye Penetrant
An inspectionpenetrant that is characterized by its abilityto fluorescewhen excitedby black light.
Halogen (Halonenous)
Any of four very active nonmetallic elements; chlorine, iodine, fluorine andbromine.
HydrophilicEmulsifier
A water-base agentthat, when appliedto an oilypenetrant, renders the penetrant water-washable. Canbe
used as a Contact Emulsifier, but more often the emulsifier is added to the water rinse and accompaniedby some
form of mechanical agitationor scrubbingto remove excess penetrant. Sometimes called a Hydrophilic Scrubber.
-~ e a kTesting
A technique of liquidpenetranttesting in which the penetrant is appliedto one side of the surface while the
other side is inspected for indicationsthat would indicate a through-leak or void.
LipophilicEmulsifier
An oil-base agentthat, when appliedto an oilypenetrant, renders the penetrant water-washable. Usually
applied as a ContactEmulsifier.
Near SurfaceDiscontinuity
A discontinuity not open to, but located near, the surfaceof a test article.
,Nonaqueous Wet Develowr
A developer in which the developingpowder is applied as a suspensionin a quick-drying solvent.Also
called Solvent Developer.
Penetrability
The property of a penetrant that causes it to find its way into very fine openings, such as cracks.
Penetrant
A liquid (sometimes gas) capable of enteringdiscontinuitiesopento the surface, and which is adaptedto
the inspection process by being made highly visible in small traces. Fluorescentpenetrants fluorescebrightly under
black light while the visible penetrants are intensely colored to be noticeable under visible light.
L

Post-emulsification Penetrant
A penetrant that requires the application of a separateemulsifierto render the surfacepenetrantwater-
washable. Also can be removed by applying a solvent remover.
Precleaning 4
The removal of surfacecontaminants or smeared metal from the test article so that they cannot interfere
with the penetrant inspectionprocess.
Ouenchin~of Fluorescence
The extinctionof fluorescenceby causes other than removal of black light (the excitingradiation).
Resolution
The property of a test systemthat enables the separation of indications of closeproximity in a test article..
Rinse-
The process of removing liquid penetrant inspection materials from the surface of an articleby washing or
floodingwith another liquid-usuallywater. Also called Wash.
See-ability
The characteristic of an indication that enablesth: observerto see it against the conditionsof background,
outside light, etc.
Self-developinnPenetrant
A penetrant not requiring the use of a developer. Useful for production work in the detectionof gross
discontinuities.
Sensitivity
.'v
The ability ofthe penetrant process to detect minute surface discontinuities.
Solvent Removed
A penetrant-removal technique wherein the excesspenetrant is washed or wiped from the test surfacewith
a solvent remover.
SolventRemover
A volatile liquid used to remow excess surfacepenetrant from the test article. Sometimes called Penetrant
Remover.
SurfaceTension
That property of liquidswhich, due to molecular forces, tends to bring the contained volume into a form
havingthe least superficialarea.
Viscosity
The stateor degree of being viscous. The resistance of a fluid to the motion of its particles.
Visible Dye Penetrant
An inspection penetrant that is characterized by its intense visible color-usually red. Also called Color
Contrast orNonfluorescent Penetrant.
Water-solubleDeveloper
A developer in which the developerpowder is dissolved in a water carrier to form a solution.Not a
d
suspension.

Water-suspended Particle Developer
A developer in which the developerparticles are mixed with water to firm a suspension.
Water-wash
L A penetrant-removal techniquewherein excesspenetrant is washed or flushed fromthe test surfacewith
water.
Water-washablePenetrant
A type of penetrant that contains its own emulsifier,making it water-washable.
Water Tolerance
The amount of water that a penetrant, emulsifier,or wet developer can absorbbefore its effectiveness is
impaired.
Wet Developer
A developer in which the developerpowder is applied as a suspensionor solution in a liquid-usually water
or alcohol.
Wetting Ability
The ability of a liquid to spread out spontaneously and adhere to the test article's surfaces.

w
(MAX# OF INDICATIONSl36)X ACTUALAREA =NEW MAX# OF INDICATIONS
I
- I .I00 .0079
Area = m2

Penetrant Wetting Characteristics
Inspector's HandGook

Chapter 4 -Magnetic Particle Testing
Common Definitions and Examples
-.& gap
When a magnetic circuit contains a small gap, which the magnetic flux must cross, the space is referred to
as an air gap. Cracks produce small air gaps on the surfaceof an article.
Alternatingcurrent
Electric current periodicallyreversing in polarity or direction of flow.
AmDere
Theunit of electrical current. One ampere is the current that flows through a conductor having a resistance
of one ohm at a potential of one volt.
Ampere turns
Theproduct of the number of turnsin a coil and the number of amperes flowingthrough it. A measure of
the magnetizingor demagnetizing strengthof the coil.
W h
The suspensionof iron oxide particles in a liquid vehicle (light oil or water).
J
Black light
Radiant energy in the near ultraviolet range. This light has a wavelength of 3200 to 4000 angstrom units
(A), peaking at 3650 A, on the spectrum. This between visible light and ultraviolet light.
$lack light filter
A filter that transmitsblack light while surprisingthe transmission of visible light and harrml ultraviolet
radiation.
Carbon steel
Steelthat doesnot contain significant amounts of alloyingelements other than carbon and maganese.
Carrier fluid
The fluid in which fluorescent and no* fluorescentmagnetic particles are suspendedto facilitate their
application in the wet method.
Central conductor
An electrical conductor that is passed throughthe opening in a ring or tube, or any hole in an article, forthe
purpose of creating a circular field in the ring or tube, or around the hole.
Circular field
See Field, Circular Magnetic.
Circularmagnetization
A method of inducing a magnetic field in an article so that the magnetic lines of force take the form of
concentricrings about the axisof the current. This is accomplishedby passing the current directly throughthe
article or through a conductor which passes into or through a hole in the article. The circularmethod is applicable
fort h detection of discontinuitieswith axes approximately parallel to the axis of current through the article.

Coercive force
The reverse magnetizing force necessaryto remove residual magnetismin demagnetizing an article.
Coil shot
A pulse of magnetizing currentpassed through a coil surroundingan articleforthe purpose of longid -magnetization.
Contact headshot
The electrode, faed to the magnetic particle testing unit, through which the magnetizing current is drawn.
Contactpads
Replaceable metal pads, usually of copperbraid, placed on contactheads to give good electrical contact
thereby preventing damage to the articleunder test.
1
Continuousmethod
An inspection method in which ample amounts of magnetic particles are applied, or arepresa on the
piece, during the time the magnetizingcurrent is applied.
Core-
That part of the magnetic circuit that is within the electrical winding.
Curiepoint
The temperature at which ferromagneticmaterials can no longer be magnetized by outside forces, and at
which they lose their residual magnetism: approximately 1200to 1600' F (646 to 871° C) for many metals.
Current Flow Technique
A technique of circular magnetizationin which current is passed through an articlevia prods or contact 4
heads. The current may be alternating,half-wave rectified, rectified alternating, or direct.
C m t Induction Technique
A technique of magnetizationin which a circulating current is induced in a ring-shaped componentby a
fluctuating magnetic field.
Demamethtion
The reduction in the degree of residualmagnetismto an acceptablelevel.
Diamagnetic
Materialswhose atomic structurewon't permit any real magnetization. Materials suchasbismuth and
copperare diamagnetic.
Diffused Indications
Indications that are not clearly defined, such as indications of subsurface defects.
Direct ContactMagnetization
A magnetic particle testing technique in which current is passed throdgh the test article. These include
headshots andprod shots.
Direct Current
An electrical current, which flows steadily in one direction
4-2 Inspector's Handboak

DistortedField
A field that does not follow a straightpath or have a uniform distribution. Thisoccursin irregularly shaped
objects.
b
Dry Medium
Magnetic particle inspection in which the particles employed are in the dry powder f o m
Dry Powder
Finely divided ferromagneticparticles suitably selected and prepared for magneticparticle inspection.
Electromagnet
A magnet created by inserting a suitablemetal core within or near a magnetizing field formed by passing
electriccurrent through a coil of insulatedwire.
Etching
Theprocess of exposing subsurfaceconditionsof metal articlesby removal of the outside surfacethrough
the use of chemicalagents. Due to the action of the chemicals in eating away the surface,various surfaceor
subsurfaceconditions are exposed or exaggerated and made visibleto the eye.
Ferromagnetic
A term applied to materials that can be magnetized and strongly attracted by a magnetic field.
Field, CircularMametic
Generally the magnetic field in and surroundingany electrical conductor or articleresulting from a current
being passed through the conductoror article or fiomprods.
.field,Longitudinal Magnetic
A magnetic field wherein the flux lines traverse the component in a directionessentiallyparallel with the
axis of the magnetizing coil or to a line connectingthe two poles at the magnetizingyoke.
Field, Magnetic
The space within and surroundinga magnetized article, or a conductor carryingcurrent in which the
magnetic force is present.
Field, MagneticLeakwe
The magnetic field that leaves or entersthe surface of an article at a magnetic pole.
Field. Multidirectional
A magnetic field that is the result of two magnetic forces impressedupon the same area of a magnetizable
object at the sametime-sometimescalled a "vector field."
Field, Residual Mametic
The field that remains in magnetizable material after the magnetizing force has been removed
Flash Magnetization
Magnetizationby a current flow of very brief duration.
Fluorescence
W ,J The emission of visibleradiationby a substanceas the result of and only duringthe absorptionof black
light radiation.

FluorescentMagnetic Particle Inspection
The magnetic particle inspection process employing a finely divided fluorescent ferromagneticinspection
medium that fluoresceswhen activated by black light.
V
Flux Density
The normal magnetic fluxper unit area It is designatedby the letter "B" and is expressed in telsa (SI units)
or gauss (cgs units).
FluxLeakage
Magnetic lines of force which leave and enter an article at poles on the surface.
FluxLines
Imaginary magnetic lines used as a means of explaining the behavior of magnetic fields. Their conception
is based on the pattern of linesproduced when iron filings are sprinkled over a piece of paper laid over a
permanent magnet. Also called Lines of Force.
Flux Penetration,Magnetic
The depth to which a magnetic flux is present in an article.
Furring
Buildup orbristling of magnetic particles due to excessivemagnetizationof the article.
Gauss
The unit of flux density.Numerically, one gauss is one line of fluxper square centimeterof area and is
designated by the letter "B." -
w
Head Shot
A shortpulse of magnetizing current passed through an articleor a central conductor while clamped
between the head contacts of a stationarymagnetizing unit for the purpose of circularly magnetizingthe article.
Heads
The clamping contacts on a stationarymagnetizingunit.
Horseshoe Magnet
A bar magnet bent intothe shape of a horseshoe sothat the two poles are adjacent. Usuallythe term applies
to a permanent magnet.
Hysteresis
The lagging of the magnetic effect when the magnetic force acting upon a ferromagneticbody is changed;
the phenomenon exhibited by a magnetic system wherein its state is influenced by its previous magnetic history.
HysteresisLoop
A curve showing the flux density, "B," plotted as a hction of magnetizingforce, "H." As the magnetizing
force is increased to the saturationpoint in the positive,negative, and positive direction sequentially,the curve
forms a characteristicS-shaped loop. Interceptsof the loop with the "B" and "H" axes and the points of maximum
and minimum magnetizing force define important magnetic characteristicsof the material.
Inductance w
The magnetismproduced in a ferromagneticbody by some outsidemagnetizing force. The magnetism is
not the result of passing current throughthe article.
4-4 Inspector's Randbook

Leakage Field
The magnetic field forced out into the airby the distortionof the fieldwithin an article.
',ifit Intensitv
L., The light energy reaching a unit of surface areaper of time.
LonnitudinalMagnetization
The process of inducing a magnetic field into the article such that the magnetic lines of force extending
through the article are approximatelyparallel to the axis of the magnetizing coil or to a line connecting the two
poles when yokes (electromagnets)are used.
Magnet, Permanent
A highly-retentivemetal that has been strongly magnetized; i.e., the alloy Alnico.
Mmetic Field Indicator
An instrument designed to detect andlor measure the flux density and polarity of magnetic fields.
MagneticField Strength
The measured intensity. of a magnetic field at a point alwaysexternal to the magnet or conductor;usually
expressed in amperes per meter or oersted (Oe).
Magnetic Material
Those materials that are attracted by magnetism.
MagneticParticles
Finely divided ferromagneticmaterial.
i/
Magnetic Particle Inspection
A nondestructiveinspection method for locating discontinuitiesin ferromagneticmaterials.
Magnetic Poles
Concentrationof flux leakage in areas of discontinuities,shape changes, permeability variations, etc.
MagneticWriting
A form of nonrelevant indications caused when the suface of a magnetizedpart comes in contactwith
anotherpiece of ferromagneticmaterial that is magnetized to a different value.
MagnetizingCurrent
The flow of either alternating, rectifiedalternating,or direct current used to induce magnetism into the
articlebeing inspected.
Magnetizin~Force
,Themagnetizing field applied to a ferromagneticmaterial to induce magnetization.
Medium
The fluid in which fluorescent and nonfluorescent magnetic particles are suspendedto facilitatetheir
application in the wet method.
b Jear SurfaceDiscontinuitv
A discontinuitynot open to, but locatednear, the surface of atest article.

Oersted
A unit of field strength, which produces magnetic inductionand is designated by the letter "H."
/
Paramagnetic 4
Materials which are slightly affected by a magnetic field. Examples are chromium, manganese, aluminun,
and platinum. A small group of these materials are classified as ferromagnetic.
Permeability
The ease with which the lines of force are able to pass through an article.
Pole-
The area on a magnetized article fiom which the magnetic field is leaving or returning to the article.
Prods
Hand-held electrodesattachedto cablesused to transmit the magnetizingcurrent from the sourceto the
articleunder inspection.
RectifiedAlternatingCurrent
Alternating current, which has been converted into direct current.
Reluctance
The resistance of a magnetic material to changes in magnetic field strength.
Residual Magnetism
The amount of magnetism that a magnetic material retains after the magnetizingforce is removed. Also
called "residual field" or "remanence." w
Residual Technique
A procedure in which the indicating material is applied after the magnetizing force has been discontinued.
Retentivity
Theabilityof a ~mterialto retain a certainportion of residual magnetization. Also known as rernanence.
Saturation
The point at which increasingthe magnetizing force produces no Mher magnetism in a material.
Sensitivity
The capacityor degree of responsivenessto magnetic particle inspection.
SettlingTest
A procedure used to determine the concentrationof magneticparticles in a medium or vehicle.
Skin Effect
The description given to alternating current magnetization due to its containmentto the surfaceof atest
article.
Solenoid (Coil)
An electricconductor formedinto a coil often wrapped around a central core of highly permeable mate ,,

Suspension
The correct term applied to the liquidbath in which the ferromagneticparticles used in the wet magnetic
particle inspectionmethod &e suspended.
>
Lrest Article
An articlecontaining known artificialor natural defectsused for checkingthe efficiency of magnetic
particle flaw detectionprocesses.
Wet Medium
An inspection employingferromagneticparticles suspended in a liquid (oil or water) as a vehicle.
Yoke
A U-shaped or C-shaped piece of highly permeable magneticmaterial, either solid or laminated, sometimes
with adjustablepole pieces (legs) amundwhich is wound a coil carrying the magnetizing current.
Yoke Magnetization
A longitudinalmagnetic fieldinduced in an articleor in an area of an articleby means of an external
electromagneishaped likea yoke.
Longitudinal MagnetizationMathFormula
45,000 (+/- lo?!)
AT =
W)
A =ampere
T =turns of the coil
L = length of the item
D =diameter or cross section of the item
The minimum UDratio is 2
The maximum L used in calculations is 20 inches

Common Types of Magnetization
CentralConductor (circular) Horse shoe (longitudinal)
Coil Shot (longitudinal)
Yoke (longitudinal)
Discontinuities
Theory: "Right-Hand Rulen
CURRENT
FLOW

Hysteresis Curve
B+ (FLUXDENSITY)
0-A = Referred to as the virgin curve
L/
A = Saturationpoint
-
B = Residual field
0-C = Coercive force
D = Reverse saturationpoint
E = Reverse residual field
0-F = Reverse coercive force
H- (MAGNETIZINGFORCE OF
OPPOSITE POLARITY TO H+) H= (MAGNETIZINGFORCE)
R (FLUXDENSITY OF
OPPOSITE POLARITY TO B+)
SLENDERLOOP WIDE LOOP
HIGH PERMEABILITY LOW PERMEABILITY
LOW RENTENTIVITY HIGH RENTENTMTY
LOW COERCIVEFORCE HIGH COERCIVEFORCE d
LOW RELUCTANCE HIGH RELUCTANCE
LOW RESIDUAL MAGNETISM HIGH RESIDUAL WU3FETISM
Inspector's Hadbook

MagneticParticleField Indicator (Pie Gage)
Eight low carbon steelpie
sections,furnacebrazed
Artificialflaw (all segment
1in. interfaces)
,' I 'I '
I Nonferroushandle of any
/J
Convenient length
Copperplate
0.010 in t0.001 in
thick 7
Braze weld or mechanically
I
attach nonferroustrunnions

Chapter 5 -Ultrasonic Testing
Common Terms and Definitions
--scan Display
A dimlav in which the received signal is displayed as a vertical displacement fiom the horizontal sweep
time trace, wkl; the horizontaldistancebetween a& G o signalsrepresentsthe sound path distance(or time of
travel) between the two.
Absorption Coefficient, Linear
The fractionaldecrease in transmitted intensityper unit of absorberthickness. It is usually designatedby
the symbol and expressed in units of cml.
Acceptance Standard
A control specimen containingnatural or artificialdiscontinuitiesthat are well defined and, in size or
extent, similarto the maximum acceptable in the product. Also may refer to the document defining acceptable
discontinuity size limits.
Acoustic Impedance
The factor which controlsthe propagationof anultrasonicwave at a boundary interface. It is the product of
the material density and the acoustic wave velocity within that material.
Amplifier
A device to increase or amplify electrical impulses.
Amplitude. Indication
b. The vertkal height of a received indication, measured fiombase-to-peak or peak-to-peak.
Angle Beam Testing
A testing method in which trammissionis at an angle to the sound entry surface.
Amle of Incidence
The angle between the incident (transmitted)beam and a normal to the boundary interface.
Angle of Reflection
.
The angle between thereflected beam and a normal to the boundary interface. The angle of reflection is
equalto the angle of incidence.
Angle of Refraction
The angle betweenthe refractedrays of an ultrasonic beam and the normal (or perpendicular line) to the
rehcting surface.
Angle Transducer
A transducerthat transmits or receives the acoustic energyat an acute angleto the surfaceto achieve a
specificeffect suchup the settingup of shear or surfacewaves in the part being inspected.
Anisotropic
A condition in which properties of a medium (velocity, for example) vary accordingto the direction in
,,vhich they are measured.

Array Transducer
A transducermade up of severalpiezoelectricelements individuallyconnected so that the signalsthey
transmit or receive nay be treated separatelyor combined as desired.
s-,
Attenuation Coefficient
A factorwhich is determined by the degree of scatteror absorptionof ultrasound energyper unit distance
traveled.
Attenuator
A device for measuring attenuation, usually calibrated in decibels (dB).
B-scan Display
A cathode-ray tube display in which the received signal is displayed as an illuminated spot. The face of the
CRT represents the areaof a verticalplane through the material. The display shows the location of a discontinuity,
as it would appear in a vertical section view through the thickness directionof the material.
Back Reflection .
The signalreceived fromthe back surfaceof a test object.
Back Scatter
Scattered signalsthat are directed back to the transmitterlreceiver.
BackgroundNoise
Extraneous signals caused by signal sources within the ultrasonic testing system, including the material in
test.
w
Barium Titanate (PolycrystalliieBarium Titanate -Barn3)
A ceramictransducer material composed of many individual crystals fired together and polarized by the
applicationof a dc field.
Baseline
Thehorizontal line acrossthe bottom of the CRT createdby the sweep circuit.
Basic.Calibration
The procedure of standardizingan instrument using calibration reflectors described in an application
. document.
Bi-modal
The propagation of sound in a test article where at least a shear wave and a longitudinalwave exists. The
operation of angle beam testing at less than first critical angle.
BoundaryIndication
A reflection of an ultrasonicbeam from an interface.
Broad Banded
Having a relatively wide frequencybandwidth. Used to describe pulses which display a wide frequency
spectnun and receiverscapableof amplifyingthem.
4

C-scan
A datapresentation method yielding a plan (top) view through the scannedsurface of the part. Through
gating, only indications arising fromthe interior of the test object are indicated.
X/
",libration
To determine or mark the graduations of the ultrasonicsystem's displayrelativeto a known standard or
reference.
Calibration Reflector
A reflector with a known dimensioned surface establishedto provide an accurately reproducible reference.
Collimator
An attachment designed to reduce the ultrasonicbeam spread.
Compensator
An electricalmatching network to compensate for circuit impedancedifferences.
CompressionalWave
A wave in which the particle motion or vibration is in the same directionas the propagated wave
(longitudinalwave).
Contact Testing
A techniqueof testing in which the transducer contacts the test surface, either directly or through a thin
layer of couplant.
Contact Transducer
A transducerwhich is coupledto a test surface either directly or through a thinfilm of couplant.
L.
ContinuousWave
A wave that continueswithout interruption.
Contracted Sweep
A contraction of the horizontal sweep on the viewing screenof the ultrasonic instrument. Contractionof
this sweeppennits viewing reflections occurring over a greater sound-pathdistance or durationof time.
Comer Effect
The strongreflectionobtained when an ultrasonicbeam is directed toward the inner section of two orthree
mutually perpendicular surfaces.
Couplant
A substance used between the face of the transducer and test surfaceto permit or improvetransmission of
ultrasonic energy acrossthis b o u n w or interface. Primarily used to remove the air in the interface.
Critical An~le
The incident angle of the sound beam beyond which a specificrefracted mode of vibration no longer exists.
CrossTalk
An unwanted condition in which acousticenergy is coupled fromthe transmittingcrystal to the receiving
.,pystalwithout propagating alongthe intendedpath throughthe material.
Ld

Damping (transducer)
Limiting the durationof vibration in the searchunit by eitherelectrical or mechanicalmeans.
Dead Zone
The distance in a material from the sound entry surfaceto the nearest inspectable sound path. 4
Decibel(dB)
The logarithmic expressionof a ratio of two amplitudesor intensitiesof acousticenergy
Delamination
A laminar discontinuity, generally an area of unbonded materials.
Delay Line
A material (liquid or solid)placed in front of a transducerto use a time delay between the initialpulse and
the fiont surfacereflection.
Delayed Sweee
A means of delayingthe startof horizontal sweep, hereby eliminatingthe presentation of early response
data.
Delta Effect
Acoustic energyre-radiated by a discontinuity.
Detectability
The ability of the ultrasonic systemto locate a discontinuity.
Difiction
The deflection, or "bending," of a wave front when passing the edge or edges of a discontinuity.
Diffise Reflection
Scattered, incoherentreflections causedby rough surfaces or associateinterfacereflection of ultrasonic
waves from irregularities of the same order of magnitude or greaterthan the wavelength.
Discontinuity
An interruptionor change in the physical structure or characteristicsof a material.
Dispersion, Sound
Scatteringof an ultrasonicbeam as a result of diffuse reflectionfrom a highly-irregular surface.
Distance Amplitude CorrectionPAC)
Compensation of gain as a function of time for difference in amplitudeof reflections fiom equal reflectors
at differentsound travel distances. Also referred to astime corrected gain (TCG),time variable gain (TVG) and
sensitivitytime control (STC).
Divergence
Spreading of ultrasonic waves after leaving searchunit, and is a functionof diameter and frequency.
Dual-Element Technique
The technique of ultrasonictesting using two transducerswith one acting as the transmitter and one as f .&
receiver.

Dual-Element Transducer
A singletransducerhousing containing two piezoelectric elements,one for transmitting and one for
receiving.
zffective Penetration
The maximum depth in a material at which the ultrasonic transmissionis sufficientfor proper detectionof
discontinuities.
ElectricalNoise
Extraneous signalscausedby externallyradiated electricalsignalsor from electricalinterferenceswithin
the ultrasonic instrumentation.
Electromametic Acoustic Transducer(EMAT)
A deviceusing the magneto effect to generate and receive acoustic signals for ultrasonic nondestructive
tests.
Far Field
The regionbeyond the near field in which areas of high and low acoustic intensity cease to occur.
First Leg
The sound path beginning at the exitpoint of the probe and extendingto the point of contactoppositethe
examination surfacewhen performing angle beam testing.
Focused Transducer
A transducerwith a concave facewhich convergesthe acousticbeam to a focal point or line at a d e f d
distance fromthe race.
LZ
Focusing
Concentrationor convergenceof energy into a smallerbeam.
Frequency
Number of completecycles of a wave motion passing a given point in a unit time (1 second); number of- - -
times a vibration is repeated at the same point in the same directionper unit time (usually per second).
Gate-
An electronicmeans to monitor an associated segmentof time, distance, or impulse.
Ghost
An indication which has no direct relation to reflected pulses fromdiscontinuitiesin the materials being
tested.
Emz(Hz)
One cycleper second.
Horizontal Linearity
A measure of the proportionality between the positions of the indications appearing on thebaseline andthe
positions of their sources.
'Immersion Testing
b
A technique of testing, using a liquid as an ultrasonic couplant, in which the test part and at least the
transducerface is immersed in the couplant and the transducer is not in contact with the test part.

Impedance (acoustic)
A material characteristicdefined as a product of particle velocity and material density.
Indication(ultrasonics)
The signaldisplayedor read on the ultrasonic systems display.
InitialPulse
The first indicationwhich may appear on the screen. This indication represents the emission of ultrasonic
energy fromthe crystal face (main bang).
Interface
The physical boundary between two adjacent acoustic mediums.
Insonification
Irradiationwith sound.
Isotropy
A condition in which significantmedium properties (velocity, for example) are the same in all directions.
LambWave
A typeof ultrasonic vibration guided by parallel surfaces of thin mediums capableof propagationin
different modes.
Linearity(area)
Asystemresponse in which a linear relationship existsbetween amplitudeof response and the
discontinuity sizesbeing evaluatednecessarilylimited by the size of the ultrasonicbeam. v
Linearity(depth)
A systemresponsewhere a linearrelationship existswith varying depth for a constant size discontinuity.
Longitudinal Wave Velocity
The unit speed of propagation of a longitudinal(compressional)wave through a material.
Loss of Back Reflection
Absence of or a significantreductionof an indication fromthe back surface of the articlebeing inspected.
Maior ScreenDivisions
The vertical graticuleused to divide the CRTinto 10equal horizontal segments.
Manipulator
A deviceused to orient the transducer assembly. As appliedto immersion techniques, it provideseither
angular or normal incidence and fmes the transducer-to-part distance.
MaterialNoise
Extraneoussignals caused by the structure of the materialbeing tested.
Miniature Angle Beam Block
A specifictype of reference standardused primarily for the anglebeam method, but alsoused for straig w
beam and surfacewave tests.
Inspeetor's Handbook

Minor ScreenDivisions
The vertical graticuleused to divide the CRT into fifty equal segments. Each major screen division is
divided into five equal segmentsor minor divisions.
; M o d eConversion
The change of ultrasonicwave propagation upon reflection or refraction at acute angles at an interface.
Mode
The manner in which acoustic energy is propagated through a material ascharacterizedby the particle
motion of the wave.
Multiple Back Reflections
Repetitive indications fromthe back d a c e of the material being examined.
Nanosecond
Onebillionth of a second.
Narrow Banded
A relative term denoting a restricted range of frequency response.
Near Field.
A distance immediatelyinfront of a transducer composedof complex and changingwave front
characteristics.Also known as the Fresnel field.
Node
The point on the examination surfacewhere the V-path begins or ends.
L.
L40ise
Any undesired indications that tend to interferewith tkinterpretationor processinn of the ultrasonic-
information;also referred to as "grass."
Normal Incidence
A condition where the angle of incidence is zero.
Orientation
The angularrelationship of a surface,plane, defect axis, etc., to a referencep l w or sound entry surface.
Penetration(ultrasonic)
Propagationof ultrasonicenergy through an article.
Phased Array
A mosaic of probe elementsin which the timing of the element's excitationcan be individuallv controlled
toproduce certaindesired effects, such as steeringthe beam axis or focusing the beam.
PiezoelectricEffect
The characteristic of certain materialsto generate electrical charges when subjectedto mechanical
vibrations and, converselyto generatemechanical vibrations when subjected to electricalpulses.

Polarized Ceramics
Ceramic materials that are sintered(pressed), created (approximately 100oOc),and polarizedby applying a
direct voltage of a few thousand volts per centimeterof thickness. The polarization is the process that makes these
ceramicspiezoelectric. Includes sodium bismuth titanate, lead metaniobate, and severalmaterialsbased on lea+
zirconatetitanate (PZT). u
Presentation
The method used to showultrasonic information. This may include (among others)A-, R,or C-scans
displayedon various types of recorders, CRTs, LCD's or computerized displays.
Probe
Transducer or searchunit.
Propagation
Advancement of a wave through a medium.
PulseEchoTechnique
An ultrasonictest technique using equipment which transmits a seriesof pulses separatedby a constant
period of time; e., energy is not sent out continuously.
PulseLen*
Time durationof the pulse fromthe searchunit.
PulseRate
For the pulse echotechnique, the number of pulses transmitted in a unit of time (also called pulse repetition
rate).
..r
RadioFrequencyDisplay(RF)
The presentationof unrectifiedsignals in a display.
i.bxs
The maximum ultrasonicpath length that is displayed.
Rarefaction
The thinning out or moving apart of the consistent particles in the propagating medium due to the
relaxation phase of an ultrasonic cycle. Opposite in its effect to compression.The soundwave is composedof
alternatecompressionsand rehctions of the particles in a material.
Raylei& WaveISurface Wave
A wave that travels on or close to the surface and readily follows the curvature of the part being examined.
Reflectionsoccur only at sharpchanges of directionof the surface.
Receiver
The sectionof the ultrasonic instrument that amplifiesthe electronicsignals returning from the test
specimen.Also, the probe that receives the reflected signals.
ReferenceBlocks
A block or seriesof blocks of material containing artificial or actual discontinuitiesof one or more
reflecting areas at one or more distances *om the sound entry surface. These are used for calibratinginstrume
and in defining the size and distance of discontinuous areas in materials.
5-8 Inspector's EI.andbook

Reflection
The characteristicof a surfaceto changethe direction of propagating acousticenergy; the retun of sound
3- -resfrom surfaces.
L
Pehction
A change in the directionand velocity of acousticenergy after ithas passed at an acute angle through an
interfacebetweentwo differentmediums.
RefractiveIndex
The ratio of the velocity of a incident wave to the velocity of the refhcted wave. It is a measure of the
amount a wave will be refracted when it entersthe secondmedium after leavingthe first.
Reiect/Suppression
An instrumentfunction or control used for reducing low amplitude signals. Use of this controlmay affect
vertical linearity.
RepetitionRate
The rate at which the individualpulses of acousticenergy are generated; also Pulse Rate.
Resolving Power
The capabilitymeasurement of an ultrasonic system to separate in time two closely spaceddiscontinuities
or to separate closely spaced,multiple reflections.
Resonance Technique
A technique using the resonance principlefor determining velocity, thickness or presence of laminar
LSiscontinuities.
,iesonance
The conditioninwhich the hquency of a forcing vibration (ultrasonicwave) is the sameas the natural
vibration frequency of the propagationbody (test object), resulting in large amplitude vibrations.
Saturation(scope)
A term used to describe an indicationof such a size as to exceed full screen height (100%).
Scanning(manual and automatic)
The moving of the searchunit or units along a test surfaceto obtaincompletetesting of a material.
Scattering
Dispersionof ultrasonic waves in a medium due to causes other than absorption
SecondLeg
The sound path beginning at the point of contact on the opposite surface and extendingto the point of
contact on the examinationsurface when performing angle beam testing.
Sensitivity
The ability to detect small discontinuitiesat given distances.The level of amplificationat whichthe
receiving circuit in an ultrasonic instrument is set.
Shear Wave
The wave in which the particles of the medium vibrate in a directionperpendicularto the directionof
propagation.
Inspector's Handbook 5-

Signal-to-Noise Ratio (SNR)
The ratio of amplitudes of indicationsfrom he smallest discontinuity considered significantand those
caused by random factors, such as heterogeneity in grain size, etc. ,-
u
Skip Distance
In angle beam tests of plate, pipe, or welds, the linear or surface distancefromthe sound entrypoint to the
firstreflection point on the same surface.
Snell's Law
The law that definesthe relationshipbetween the angle of incidence and the angle of refkction across an
interface, based on a range in ultrasonic velocity.
Specific Acoustic Impedance
A characteristicwhich acts to determine the amount of reflection which occurs at an interface and
represents the wave velocity and the product of the density of the medium in which the wave is propagating.
StraightBeam
An ultrasonicwave traveling normal to the test surface.
Sweep
Theuniform and repeated movement of a spot acrossthe screen of a CRTto formthe baseline.
Through-Transmission
A test technique using two transducersin which the ultrasonic vibrations are ernittedby one and received
by the other, usually on the opposite side of the part. The ratio of the magnitudes of vibrationstransmitted and
received is used as the criterion of soundness. ' 4
Tip Diffiction
Theprocessby which a signal is generatedfrom the tip (i.e., top of a fatigue crack)of a discontinuity
through the interruptionof an incident sound beam propagating through a material.
Transducer (search unit)
An assembly consistingbasically of a housing, piezoelectric element, backing material, wearplate
(optional) and electrical leads for converting electrical impulses into mechanical energy and vice versa.
TransmissionAngle
The incident angle of the transmittedultrasonicbeam. It is zero degrees when the ultrasonicbeam is
perpendicularto the test swface.
Transmitter
The electricalcircuit of an ultrasonic instrument that generatesthe pulses emittedto the searchunit. Also
the probe that emits ultrasonic signals.
Two Probe Method
Use of two transducers for sendingand receiving. May be either send-receive or through transmission.
Ultrasonic Absorption
A dampingof ultrasonic vibrationsthat occurswhen the wave transversesa medium.

Ultrasonic Spectrum
The frequency span of elastic waves greaterthan the highest audible kquency, generallyregarded asbeing
higher than 20,000 hertz, to approximately 1O00megahertz.
'Jltrasonic Svstem
Thetotality of componentsutilized to perform an ultrasonic test on a test article.
V-path
Thevath of the ultrasonic beam in the test object fromthe point of entry on the examination surface to the
back surface'and reflecting to the front surface again.
Velocity
The speed at which sound travelsthrough a medium.
Video Presentation
A CRT presentationin which radio frequency signalsnave been rectified and usually filtered.
Water Path
The distancefnrmthe face of the searchunit to the entry surface of the materialunder test in immersion
testing.
Wavelength
The distance in the direction of propagationfor a wave to go through one completecycle.
Wedgelshoe
A deviceused to adapt a straightbeam probe for use in a specifictypeof testing, including angle beam or
Ld a c e wave tests and tests on curved surfaces.
Wraparound
Nonrelevant indications that appearon the CRT as a result of a shortpulse repetitionrate in the pulser
circuit of the test instrument.

CommonMath Formulas
Wavelength
L
I
T
5-12 Inspectar's Handbook
r ? = Wavelength
V = Veloocity
F = Frequency
ReflectedAcoustic Energy
21-22 ) 2
ER= 100 (-
21+22
ER= Energy reflected
Z1 = Acoustic impedance material#1
22 = Acoustic impedance material#2
Nearfield (nearzone) u
N =
D * (F)
4 (V)
N = Length of the near field
D = Diameter of the transducer
F = Transducer frequency
V = Materials velocity
CrystalThickness
hCT =
2
CT = Crystalthickne$s
h = Wavelength
Use .23 if material is unknown
Energy Transmitted
ET = El -ER
ET = Energytransmitted
El = Energyintiated
ER = Energy reflected
Acoustic Impedance
z = POI)
Z = Acoustic impedance
P = Materialsdensity
V = Acousticvelocity
HalfAngle Beam Spread
vSIN 0 = K ( )
D*F
K= 1.22
V = Velocity of the material
D = Diameterof the transducer
F = Frequencyof the transducer
Times2 forfull anglebeam spread
Decibel Difference
A1
Db=20 [LOG (-)IA2
Db= Decibel difference
LOG= Naturallogrithm
A1= Amplitude number one
A2 = Amplitude number two
Rule ofthumb:every 6 Db doublesthe size of the
indicationheight (pip)
Snell's Law & Angle of Reflection
SIN 01 =
SIN 02 * V1
V2
Angle of incidence * 1stcritical angleV2 is long = 90°
Critical angle* 2nd criticalangleV2 is shear = 90°
Wedge angle
SIN 02 = 'IN * V2
v1

Half / Full Sound Path & Skip / SetbackDistance
T HALF SKIP = T TAN 8
HSP= -COS 0
2T FULL SKIP = 2T * TAN 0
FSP= -cose
T =Memberthickness
Surface Distance to Defect / Depth of Defect
SDD = Sound Path* SIN 8 #DD =Sound Path* COS 8
##DD =(Sound Path* COS 0) - 21
SDDSurface distanceto defect
#DD=Depthof defedduringhalfsound path
##OD =Depthofdefectduringfull sound path
T=Memberthickness
CalibrationChart-UT Shearwave
b
PLATE
THICKNESS *HALF SKIP
1" 112" 314" 1"
PLATE
THICKNESS FULL SKIP
I 1 - 112" 1 -314" 2"
* Applicableholesinthe M.I. blockfor calibration

Velocity Chart
I I I LONGITUDINAL 1 SHEAR I ACOUSTIC 1
Aluminum
Aluminum Oxide
Bertilium
Copper I 8.9 I -18 I .089 I 41.6
CrownGlass 2.5 .21 .I2 18.9
Ice 1.OO .I6 .08 3.5
,Inconel - - - - .22 .I2 47.2
Iron - - - - .23 .I3 45.4
2.7
- - - -
1.82
.43 I - - - - I
,#~&~~~;@~$~g+;~~~~$[@:@~,t
KrTnCarbie I - - - -
Mercurv - - - - .057 I - -- - I 19.6
Molvbdenum 1 10.09 1 .25 .I3 64.2
Cadium 8.6 .ll 1 .059 ! 24
, , ,-,*,.,. $>, . s , , ~v.x<,,,, ..",
~~~&~'i~$&iia$gfigp&+
.25
.39
-51
$~f&<gg$-@@#
lOil (SAE 30) I 0.95 1 .067 I ---- 1.5 I
Monel - - - -
' ,"":G,~w$~.~$s~&-&~.,, ";?$;>$..p$",2$$2
~~~wp&n8:F~w~;&~k~&iyr.~I-j~.t~~...
Nickel I 8.3
.I2
.23
.35
Steel, Mild I 7.7 I .23 I .I3 I 46
,Steel, Stainless I 8.03 1 .23 -12 I 45.4
17
32
23
.21 I -11
~%;62%,:*, "' y , ' ' % ~ ; ~ ~ ~ ~!$%:?>&@&$?& & ,..<::
;&4~;.~~%<~$~&~~i-~f,6"t*~5-i.&i&+&r.
-22 I .12
Polyethylene
Polvstyrene
Polyurethane
47.6
2@&d@@& ' w'*'",*
;>:'. 5~;,%k.a3g&&g$$
49.5
- - - -
1.06
- - - -
Titanium
Tungsten
Uranium
.07
.093
.07
4.54
19.25
- - - -
.02
.04
----
.24
.20
.I3
1.7
2.5
1.9
-12
.I1
.OW
27.3
101
63

Chapter 6 -Eddy Current Testing
Common Terms and Definitions
AbsoluteCoil
b A test arrangementwhich teststhe specimenwithout any comparisonto eitheranotherportion of the test
specimenor to a known reference.
Alternating
A voltage, current or magnetic field that reverses direction at regularly recurring intervals.
Bobbin Coil
A coil or coil assemblyused foreddy current testing by insertion into the test piece; e.g., an inside probe
for tubing. Also referred to as Inside Coil or IP Coil.
Coil-
Conductor wound in one or more loops to produce an axialmagnetic fieldwhen current is passed through
it.
Coil Spacing
The axial distance between two encirclingcoils of a differential system.
Conductivity
/
Thewillingness of a test circuit or test specimento conduct current.
Coupling
A measure of the degree to which the magnetic field of the coil passes through the test specimenand is
w ffkted by the magnetic field created by the flow of eddy currents.
Defed Resolution
A property of a test systemwhich enables the separationof signalsdue to defects in.thetest specimenthat
are located in close proximity to each other.
Diamagnetic
A material having a permeability less than that of a vacuum.
Differential Coil
A test arrangement which tests the specimenby comparing the portion being tested with eitheranother
portion of the same specimenor to a known reference specimen.
Discontinuitv, Artificial
Reference discontinuities, such as holes, grooves, or notches, which are introducedinto a reference
standardto provide accurately reproducible sensitivitylevels for electromagnetic test equipment.
Double Coil
A test arrangement where the alternating current is suppliedthrough one coil while the changein material
conditionis measured from a second coil.
Eddy Current
L A circulating electricalcurrent induced in a conductivematerial by an alternatingmagnetic field.

Edge or End Effect
The disturbance of the magneticfield and eddy currents due to the proximity of an abrupt change in
geometry (edge, end). The effect generally results in the masking of discontinuitieswithin the affected region.
f
Effective Depthof Penetration d
The depth in a material beyond which a test system can no longer detect a changein material properties.
EffectivePermeability
A hypothetical quantity
conductorin an encirclingcoil.
which is used to describethe magnetic field distributionwithin a cylindrical
The field strengthof the applied magnetic field is assumed to be uniform over the
entire cross section of the test specimenwith the effectivepermeability, which is characterized by the conductivity
and diameter of the test specimen and test frequency, assumingvalues between zero and one, suchthat its
associated amplitude is always less than one within the specimen.
ElectromagneticInduction
The process by which a varying or alternatingcurrent (eddy current) is induced into an electrically
conductivetest object by a varying electromagneticfield.
ElectromagneticTesting
That nondestructivetest method for engineeringmaterials, includingmagnetic materials, which uses
electromagnetic energy having frequencies less than those of visible light to yield information regarding the quality
of the tested material.
Encircling Coil
A coil, coils, or coil assemblythat surroundsthe part to be tested. Coils of this type are also referred to as
circumferential, OD or feed-throughcoils.
w
External ReferenceDifferential
A differentialtest arrangement that compares a portion of the test specimento a known reference standard.
Ferromagnetic
A material which, in general, exhibitshysteresisphenomena, and whose permeability is dependent on the
magnetizing force.
Fill Factor
For an inside coil, it is the ratio of the outside diameter of the coil squaredto the inside diameter of the
specimen squared. For an encircling coil, it is the ratio of the outsidediameter of the specimen squaredto the
inside diameter of the coil squared.
Flux Density
A measure of the strength of a magnetic field expressed as a number of flux lines passing through a given
area.
Henry
The unit of inductance. More precisely, a circuit in which an electromotive force of one volt is induced
when the current is changing at a rate of one ampere per second will have an inductanceof one henry. (Symbol: H)
Hertz
The unit of frequency (one cycle per second). (Symbol: Hz)

High Pass Filter
An electroniccircuit designedto block signals of low frequencywhile passing high frequency signals.
IACS
k The International Annealed Copper Standard. A value of conductivity establishedas a standard againstw
which other conductivityvalues are referred to in percent IACS.
Impedance
The ovtmsitionto current flow in a test circuit or a coil due to the resistance of that circuit or coil, plus the
electrical of the coil as affectedby the coil's magnetic field.
Impedance Analysis
An analyticalmethod which consists of correlating changes in the amplitude,phase, or quadrature
components (or all of these) of a complex test signalvoltage to the electromagneticconditionswithin the
specimen.
Impedance-planeDiagram
A graphical representationof the locus of points indicatingthe variations in the impedanceof a test coil as
afunction of basic test parameters.
Inductance
The inertial element of the electriccircuit. An inductor resists any sudden change in the currentflowing
through it.
Inductive Reactance
The opposition to current flow in a test circuit or coil when an alternatingvoltage source is applied and due
solelyto the electricalproperties of the mil as affected by the magnetic field.
b
Inertia
Thepropertyof matter which manifests itself as a resistance to any change in the momentum of a body.
Lift-off
The distancebetween a swfaceprobe coil and the specimen.
Lift-off Effect
The effed observed dueto a change in magnetic couplingbetween a test specimenand aprobe coil
whenever the distance between them is varied.
Low Pass Filter
An electroniccircuit designedto block signals of high frequency while passing low frequency signals.
MagneticField
A condition of space near a magnet or current-carrying wire in which forcescan be detected.
MagneticFluxLines
A closed curve in a magnetic field throughpoints having equal magnetic force and direction.
Noise
Any undesired signalthat tendsto interfere with the normal receptionor processing of a desired signal.. In
haw detection, undesired response to dimensional and physical variables (otherthan flaws) in the test part is called
"partnoise.

Nonferroma.gnetic
A material that is not magnetizable and hence, essentially not affected by magnetic fields. This would
includeparamagnetic materials having a magneticpermeability slightlygreater than that of a vacuum and
approximatelyindependent bf the magnetizing force and diamagneticmaterials having a permeability less tha- ''
of a vacuum. V
Paramagnetic
A material having a permeabilitywhich is slightlygreater than that of a vacuum, and which is
approximatelyindependent of the magnetizing force.
Permeability
A measure of the ease with which the magnetic domains of a material align themselves with an externally
applied magnetic field.
PermeabilityVariations
Magnetic inhomogeneitiesof a material.
Phase Analysis
An instrumentationtechnique which discriminatesbetween variables in the test part by the differentphase
angle changes which these conditionsproduce in the test signal.
Phase Angle
The angle measured degreesthat the current in the test circuit leads or lags the voltage. One complete
cycle is equal to 360".
Phase Shift
A change in the phase relationship between two alternating quantitiesof the same frequency. w
Probe Coil
Asmall coil or coil assemblynormally used for surfaceinspections.
- ReferenceStandard
A test specimenused as a basis for calibrating test equipment or as a comparisonwhen evaluatingtest
results.
Reiection Level
The setting of the signallevel above or below which allparts arerejectable or in an automatic system at
which objectional parts will actuatethe reject mechanism of the system.
Resistance
The opposition to current flow in a test circuit or coil based on specificmaterial properties and cross-
sectionalarea and length of a conductor.
Response Amplitude
The property of the test systemwhereby the amplitudeof the detected signalis measuredwithout regard to
phase.
Saturation
The degree of magnetizationproduced in a ferromagneticmaterial for which the incremental permeabili
has decreased substantially to unity.

Self-comparison Differential
A differentialtest arrangementthat comparestwo portions of the sametest specimen.
Signal-to-noise Ratio
L The ratio of responseor amplitudeof signalsof interestto the response or amplitude of signals containing
no usell information.
SingleCoil
A test arrangement where the alternating current is supplied through the same coil from which the-
indication is taken.
Skin Effect
A phenomenon where, at high frequencies, the eddy current flow is restrictedto a thin layer of the test
specimen close to the coil.
Standard
A referenceused as a basis for comparison or calibration;a concept that has been establishedby authority,
custom, or agreement to serve as a model or d e in the measurement of &tity or the establishment of a practice
or a procedure.
StandardDepth of Penetration
The depth in a test specimenwhere the magnitude of eddy currentflow is equal to 37 percent of the eddy
current flow at the surface.

Two Types of Electrical Current
Direct Current (DC)
4
- Current flowis constant over time
- Current is distributeduniformly over the cross-sectionof the conductor
- Example: battery
Current strength and direction remain constant overtime
Time
AlternatingCurrent (AC)
- Current flow varies over time w
- Current flows at or near the surfaceof the conductor -this phenomenon is called the SL,
effect
- Example: 60 cycle ac in wall sockets
Current strengthvaries over time; current
directionreverses every 112 cycle
Time
Inspector's Handbook'

Conductivityand the IACS
Conductivityof a metal is usually expressed as a percentage (%) and is based on the internationalannealed copper
standard (IACS).
k .
A specificgrade of high purity copper was designatedas 100%conductivity.All other metals (except silver)are
designated some %less then 100%. These percentages indicatethe relative efficienciesof the various metals for
carrying electric current.
Right Hand Rule
L
An easy method for fmding the direction of an electricallyinduced magnetic field is to imagine graspingthe
conductorin the right hand with the thumb pointing in the direction of the current flow. The fingerswill then point
in the direction of the lines of force. This is the right hand rule and is shownbelow. From this figureit can be seen
that the current flow in the conductorcreates circular lines of force.
CURRENT
FLOW
The coil's magnetic field intensity (strength)decreaseswith'in~reasin~distanceaway from the outside of the coil.
C*
The field intensity at point C is less
than at point B, and point B's intensity
C is less than point A's
B
A

C1
The coil's field intensity (strength) is assumed to be constant across the inside
diameter of the coil. This assumption is based on the use of AC and small
diameter coils, and for all practicalpurposes the assumptionis valid. W'
' ./-Y
Lines of
Force
The coil's magnetic field can be viewed as a distributionof lines of
force aroundthe coil. These lines of force are call magnetic flux, and
represent the coil's magnetic force (symbol 'H').
Current Current
in
- 0 -
out
C . - -
-0
I
When a metal rod is placed insidethe coil, the coil fluxpasses through the
rod. The number of lines of force in the rod divided by the cross-sectional 'N
area of the rod equals the flux density (symbol 'B') in the rod. The flux
density in the rod depends on the metal's willingness to cany the magnetic ,'flux. The metal's willingness to carry these magnetic flux lines is called /
permeability. The symbol for permeability is 'p'(mu).
'
N - * ---I- w
Mathematically,permeabilityis expressed as the flux density in the material (B) divided by the magnetizingforce
(H) that caused it.
Permeability
B
= o r p
H
Flux densih
Magnetizing force
Like conductivity,permeability is a material property that is the same for all samples of a particularmaterial
(assume same chemistry, etc.).
example: p,for air = 1
p for copper alloys= 1
p,for steels = severalthousand

The permeability value of 1 for air and copper alloys(and all other nonmagneticmaterials)means that the
magnetic flux in the material is exactly equal to the flux coming from the coil.
b
stated another way: b/h = 1 only when b =h
The high permeability value of steels (and all other ferromagneticmetals) means that the magneticflux inthe
metal is thousands of times greater than the applied flux fiom the coil.
stated another way: b/h =2000 means h,,= 2000 x h,,
Magnetic Domains
Obviously, somethingis happening in the ferromagnetic metals to create all this additional flux that is not
happening in the nonmagnetic materials. Magnetic domainsare groups of atoms within a ferromagneticmetal
which behave like tiny permanent magnets.
In unmagnetized magnetic materials, the domains are randomly oriented
and neutralize each other, producing no observable magnetic flux in the
. metal.
w
When the magnetizing force fiom the coil, is applied, the domains begin
to align in the directionof the appliedflux. Their combined individual
magnetism startsto produce an observable increasein the flux in the
metal, over and above the applied flux (H).
When the domains are completelyaligned, the metal is said to be
saturated, and the flux 'B' is many thousands of times greater than the
applied flux 'HI. This domainbehavior is responsible for the mrrlinear
relationship between (E3) and (H) in ferromagneticmetals and for the
hysteresis effect.
Partially Oriented Domains
Completely Oriented
Domains (saturation)

NDT HANDBOOK

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie NDT HANDBOOK

Ähnlich wie NDT HANDBOOK (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

NDT HANDBOOK