Electromagnetic Testing

More documents

Recommendations

Info

Proximity / Lift-off The closer a probe coil is to the surface the greater will be the effect on that coil. This has two main effects: The "lift-off" signal as the probe is moved on and off the surface. A reduction in sensitivity as the coil to product spacing increases. Depth of penetration The eddy current density, and thus the strength of the response from a flaw, is greatest on the surface of the metal being tested and declines with depth. It is mathematically convenient to define the "standard depth of penetration" where the eddy current is 1/e (37%) of its surface value. The standard depth of penetration in mm is given by the formula: Where: δ is standard depth in mm ρ is resistivity in μΩ.cm f is frequency in Hz μ r is relative permeability Charlie Chong/ Fion Zhang http://www.eng.morgan.edu/~hubert/IEGR470/eddycurrent.html
from this it can be seen that depth of penetration: 1. Decreases with an increase in frequency 2. Decreases with an increase in conductivity 3. Decreases with an increase in permeability: this can be very significant penetration into ferrous materials at practical frequencies is very small. δ δ The graph above shows the effect of frequency on standard depth of penetration. It is also common to talk about the "effective depth of penetration" usually defined as three times the standard depth, where eddy current density has fallen to around 3% (5%?) of its surface value. This is the depth at which there is considered to be no influence on the eddy current field. Charlie Chong/ Fion Zhang http://www.eng.morgan.edu/~hubert/IEGR470/eddycurrent.html
Page 1 and 2: Electromagnetic Testing Study Guide
Page 3 and 4: E&P Applications Charlie Chong/ Fio
Page 5 and 6: Charlie Chong/ Fion Zhang
Page 7 and 8: 乱七八糟 - 随看随记 C
Page 9 and 10: Charlie Chong/ Fion Zhang
Page 11 and 12: Charlie Chong/ Fion Zhang http://ww
Page 13 and 14: IVONA TTS Capable. Charlie Chong/ F
Page 15 and 16: EDDY CURRENT an Overview Descriptio
Page 17 and 18: Tangential Probe Charlie Chong/ Fio
Page 19 and 20: Electromagnetic Testing Advantages
Page 21: Factors Affecting Eddy Current Resp
Page 25 and 26: http://www.eng.morgan.edu/~hubert/I
Page 27 and 28: Robotic Charlie Chong/ Fion Zhang
Page 29 and 30: Measurement Techniques (EN!) a) Abs
Page 31 and 32: Figure 1.1 Arago’s Experiment Cha
Page 33 and 34: Oersted discovered the presence of
Page 35 and 36: Figure 1.3: Induced current electro
Page 37 and 38: Charlie Chong/ Fion Zhang http://en
Page 39 and 40: Charlie Chong/ Fion Zhang http://en
Page 41 and 42: The law of physics describing the p
Page 43 and 44: Charlie Chong/ Fion Zhang http://hy
Page 45 and 46: Magnetic Force The magnetic field B
Page 47 and 48: Generation of Eddy Currents When a
Page 49 and 50: Factors Affecting Inductance There
Page 51 and 52: COIL LENGTH: All other factors bein
Page 53 and 54: Coil Inductance L An approximation
Page 55 and 56: Note the direction of the primary c
Page 57 and 58: Generation of Eddy Current With a p
Page 59 and 60: Charlie Chong/ Fion Zhang Permeabil
Page 61 and 62: A Dual Variable inductors Figure 1:
Page 63 and 64: Figure 3: Here is another inductor
Page 65 and 66: Figure 4: The two inductors on this
Page 67 and 68: Grundig radio satellit 750 ■ http
Page 69 and 70: Figure 1.7: Phasor Diagram of Coil
Page 71 and 72: Current Density The distribution of
Page 73 and 74:
Figure 1.8: Relative eddy current d
Page 75 and 76:
Relative Magnetic Permeability Perm
Page 77 and 78:
It should be observed at this point
Page 79 and 80:
δ = (π x 100 x 10 3 x 4 x π x 0.
Page 81 and 82:
Using 1.35 mm as depth x from surfa
Page 83 and 84:
Standard Depth for Different Conduc
Page 85 and 86:
Current (?) Lagging Voltage lagging
Page 87 and 88:
σº∙πμ■δ∝∞ωΩθ√ρβ
Page 89 and 90:
Figure 1.9 should be used as a rela
Page 91 and 92:
Figure 1.8: Relative eddy current d
Page 93 and 94:
Q.1.1 Generation of eddy currents d
Page 95 and 96:
Q.1.5 Eddy current generated a test
Page 97 and 98:
Q.1.9 Refer to Figure1.9 using exam
Page 99 and 100:
Chapter 2 The Coil Arrangements Cha
Page 101 and 102:
Probe coils and probe coil forms ca
Page 103 and 104:
Encircling Coils Encircling coil, o
Page 105 and 106:
Discussion Subject; Encircling Coil
Page 107 and 108:
Bobbin Coils Bobbin coil, inside di
Page 109 and 110:
Figure 2.5: Test coil configuration
Page 111 and 112:
Differential coils Differential coi
Page 113 and 114:
Figure 2.6: External reference diff
Page 115 and 116:
Figure 2.7: Hybrid coil (through tr
Page 117 and 118:
Additional Coil Characteristics Coi
Page 119 and 120:
Q.2.1 Differential coils are usuall
Page 121 and 122:
Q.2.6 An absolute coil measurement
Page 123 and 124:
The Answers Charlie Chong/ Fion Zha
Page 125 and 126:
As discussed earlier test coil desi
Page 127 and 128:
Demonstration model of a moving iro
Page 129 and 130:
Thus, the resistance of a 10 ft len
Page 131 and 132:
SPECIFIC RESISTANCE OR RESISTIVITY
Page 133 and 134:
Problem: What is the resistance of
Page 135 and 136:
The inductance of a multilayer air
Page 137 and 138:
Example: A coil whose dimensions ar
Page 139 and 140:
Example: Using the 32 μH coil calc
Page 141 and 142:
Impedance To explain the addition o
Page 143 and 144:
Maximum transfer of power is accomp
Page 145 and 146:
Rectangular Notation Because reacta
Page 147 and 148:
Vectors With Polar Notations. Stand
Page 149 and 150:
Rectangular Notation - Prefix “j
Page 151 and 152:
Imaginary Component In “rectangul
Page 153 and 154:
Imaginary Charlie Chong/ Fion Zhang
Page 155 and 156:
To convert from rectangular to pola
Page 157 and 158:
More Reading on Polar & Rectangular
Page 159 and 160:
Eddy current coils with included im
Page 161 and 162:
Permeability and Shielding Effects
Page 163 and 164:
Another technique of shielding uses
Page 165 and 166:
Saturation Approach Another coil de
Page 167 and 168:
Figure 3.5: Magnetic bias probe Cha
Page 169 and 170:
Materials must be chemically compat
Page 171 and 172:
Q.3.1 A coil's resistance is determ
Page 173 and 174:
Q.3.7 The Q or merit of a coil is d
Page 175 and 176:
Page 177 and 178:
Jackfruit Tree Charlie Chong/ Fion
Page 179 and 180:
Electrical Conductivity σ In elect
Page 181 and 182:
As previously discussed, conductivi
Page 183 and 184:
Figure 4.1; Conductivity curve Char
Page 185 and 186:
The coil's inductive reactance is r
Page 187 and 188:
Effects of Heat Treatment on Conduc
Page 189 and 190:
Permeability Permeability of any ma
Page 191 and 192:
When increases in the magnetizing f
Page 193 and 194:
Skin Effect Charlie Chong/ Fion Zha
Page 195 and 196:
Discussion Subject: Response to the
Page 197 and 198:
Lift Off Electromagnetic coupling b
Page 199 and 200:
Fill factor will always be a number
Page 201 and 202:
Figure 4.4: Fill factor ratios When
Page 203 and 204:
Example: Calculate the resultant lo
Page 205 and 206:
Figure 1.8 is again useful to illus
Page 207 and 208:
Signal-to-Noise Ratio Signal-to-noi
Page 209 and 210:
Page 211 and 212:
Q.4.4 A (?) prime factor affecting
Page 213 and 214:
Q.4.10 Temperature changes, vibrati
Page 215 and 216:
Test Frequencies It is the responsi
Page 217 and 218:
Single Frequency Systems Unfortunat
Page 219 and 220:
Eddy Current Density Since the sens
Page 221 and 222:
Applicable Scenario Eddy Current De
Page 223 and 224:
Standard Depth δ Formula The depth
Page 225 and 226:
Example 1: As an example of how thi
Page 227 and 228:
Frequency Selection - Ferromagnetic
Page 229 and 230:
A frequency can always selected to
Page 231 and 232:
Figure 5.1(a) shows the effect on p
Page 233 and 234:
Figure 5.1: Effects of frequency ch
Page 235 and 236:
Figure 5.2: Normalized impedance di
Page 237 and 238:
Figure 5.3: Impedance variations ca
Page 239 and 240:
Figure 5.4: Impedance variations ca
Page 241 and 242:
Multiparameter Techniques It become
Page 243 and 244:
Multiparameter Techniques - Multipl
Page 245 and 246:
First, a frequency is selected to g
Page 247 and 248:
More Reading on Characteristic Para
Page 249 and 250:
Figure 1: Eddy Current Testing Char
Page 251 and 252:
Figure 2: Types of Probes Charlie C
Page 253 and 254:
Surface (Pancake) Probes Surface pr
Page 255 and 256:
Encircling Probes Encircling probes
Page 257 and 258:
Design of eddy current probes In mo
Page 259 and 260:
In brief, probe design is usually d
Page 261 and 262:
Analytical Approach (Pc & f g ) Ana
Page 263 and 264:
RECENT TRENDS IN EDDY CURRENT PROBE
Page 265 and 266:
Pressurized Heavy Water Reactors (P
Page 267 and 268:
Page 269 and 270:
Q.5.4 Calculate the limit frequency
Page 271 and 272:
Q.5.7 Primary resistance is subtrac
Page 273 and 274:
Q5.9 A 25% deep crack open to the n
Page 275 and 276:
Chapter 6 Instrument Systems Charli
Page 277 and 278:
Eddy Current Instrumentation Most o
Page 279 and 280:
Figure 6.1: Internal functions of t
Page 281 and 282:
Chernobyl Nuclear Power Plant Charl
Page 283 and 284:
Figure 6.2: Four types of simple ed
Page 285 and 286:
Figure 6.2(b) shows an impedance br
Page 287 and 288:
Figure 6.2(d) illustrates a balanci
Page 289 and 290:
Eddy current testing - Signal Analy
Page 291 and 292:
Impedance Testing With impedance ma
Page 293 and 294:
Phase Analysis Testing - Vector Poi
Page 295 and 296:
Phase Analysis Testing - Ellipse As
Page 297 and 298:
Figure 6.4: Cathode ray tube displa
Page 299 and 300:
Figure 6.5: Screen image of a linea
Page 301 and 302:
Impedance Plane Testing - Mode of O
Page 303 and 304:
Figure 6.6: Null balance instrument
Page 305 and 306:
Figure 6.7: Typical surface riding
Page 307 and 308:
For deep subsurface crack detection
Page 309 and 310:
Multiple circuits are used througho
Page 311 and 312:
This type of digital instrumentatio
Page 313 and 314:
Page 315 and 316:
Read Out Mechanisms - Audio Alarms
Page 317 and 318:
An qualitative meter response could
Page 319 and 320:
Figure 6.13: A qualitative analog m
Page 321 and 322:
Read Out Mechanisms - Cathode Ray T
Page 323 and 324:
Figure 6.14: Numerical readouts/dig
Page 325 and 326:
Read Out Mechanisms - Computer Eddy
Page 327 and 328:
Page 329 and 330:
Probe Delivery System Instead of mo
Page 331 and 332:
Chapter 6 Review Questions Charlie
Page 333 and 334:
Q.6.1 Signal preparation is usually
Page 335 and 336:
Q.6.7 Amplitude gates provide a tec
Page 337 and 338:
Chapter 7 Eddy Current Applications
Page 339 and 340:
Discontinuity Detection The theoret
Page 341 and 342:
Heat Exchanger Charlie Chong/ Fion
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Heat Exchanger TSP Charlie Chong/ F
Page 351 and 352:
Heat Exchanger TSP Charlie Chong/ F
Page 353 and 354:
Figure 7.2: Phase-to-depth calibrat
Page 355 and 356:
The geometry of real discontinuitie
Page 357 and 358:
Figure 7.5: A multifrequency applic
Page 359 and 360:
Aerospace Applications Charlie Chon
Page 361 and 362:
The reference specimen and its asso
Page 363 and 364:
Dimensional Measurements Dimensiona
Page 365 and 366:
Figure 7.6: A single frequency hard
Page 367 and 368:
Conductivity Measurements Conductiv
Page 369 and 370:
Alloy Sorting Alloy sorting can als
Page 371 and 372:
In addition, it is advisable to hav
Page 373 and 374:
Answers Charlie Chong/ Fion Zhang
Page 375 and 376:
Q.7.4 Using multifrequency techniqu
Page 377 and 378:
Q.7.7 Response to multilayer varyin
Page 379 and 380:
Chapter 8 Other Electromagnetic Tec
Page 381 and 382:
Some other technologies that have b
Page 383 and 384:
Alternating current field measureme
Page 385 and 386:
Figure 8.1 shows the basic principl
Page 387 and 388:
ACFM Principle Charlie Chong/ Fion
Page 389 and 390:
ACFM Z X Bx =magnetic flux componen
Page 391 and 392:
Page 393 and 394:
The technique in its simplest form
Page 395 and 396:
Page 397 and 398:
Magnetic Flux Leakage Testing Prima
Page 399 and 400:
Figure 8.2: Equipment for magnetic
Page 401 and 402:
Magnetic Flux Leakage Testing Charl
Page 403 and 404:
The most commonly used inservice in
Page 405 and 406:
Magnetic Saturation Charlie Chong/
Page 407 and 408:
The magnetization curve is not retr
Page 409 and 410:
Magnetic Flux Leakage Testing Charl
Page 411 and 412:
Magnetic Flux Leakage The basic pri
Page 413 and 414:
Magnetic Flux Leakage Magnetic Flux
Page 415 and 416:
Special hybrid (driver/pick up) coi
Page 417 and 418:
At distances in excess of two tube
Page 419 and 420:
Figure 8.4: Remote field testing en
Page 421 and 422:
Remote-Field Energy Zones - in remo
Page 423 and 424:
Remote-Field Zone Transition Zone C
Page 425 and 426:
RFT - Flux distribution in pipe (a)
Page 427 and 428:
Remote Field Zone - The third defin
Page 429 and 430:
Amplitude (voltage) - The remote fi
Page 431 and 432:
RFT Charlie Chong/ Fion Zhang http:
Page 433 and 434:
The Remote Field Technique is an el
Page 435 and 436:
Remote Field Eddy Current Technique
Page 437 and 438:
More Reading: RFT Remote Field Test
Page 439 and 440:
These eddy currents, in turn, produ
Page 441 and 442:
The Zones Direct Couple Zone The re
Page 443 and 444:
RFT Probes Probes for inspection of
Page 445 and 446:
RFT Signal Interpretation The signa
Page 447 and 448:
RFT Reference Standards Reference s
Page 449 and 450:
Page 451 and 452:
Q.8.4 A generally accepted definiti
Page 453 and 454:
Q.8.8 The region of intense electro
Page 455 and 456:
Chapter 9 Eddy Current Procedures,
Page 457 and 458:
American Society for Testing and Ma
Page 459 and 460:
Military Standard The United States
Page 461 and 462:
EDDY CURRENT INSPECTION OF NONFERRO
Page 463 and 464:
. Probe positioning and feeding sha
Page 465 and 466:
3. Tube Inspection General (Refer t
Page 467 and 468:
F. INSPECTION RESULTS AND DOCUMENTA
Page 469 and 470:
G. REFERENCES The following documen
Page 471 and 472:
Page 473 and 474:
Q.9.4 Military Standards are design
Page 475 and 476:
Q.9.10 The system in QA3 is calibra
Page 477 and 478:
More Reading http://www.allaboutcir
Page 479 and 480:
Discussion Subject: discuss on the
Page 481 and 482:
Charlie Chong/ Fion Zhang
Page 483 and 484:
Inspection from the Tube OD Most AS
Page 485 and 486:
Approximately 25 years ago, the AST
Page 487 and 488:
One additional advantage of OD ECT
Page 489 and 490:
The baseline eddy current test The
Page 491 and 492:
There is no standard accept/reject
Page 493 and 494:
Pulsed Eddy Currents Systems Charli
Page 495 and 496:
Although still an active research f
Page 497 and 498:
LOI (Lift-Off point of Intersection
Page 499 and 500:
Gap Point : Similar to the LOI, the
Page 501 and 502:
Driving Coil Charlie Chong/ Fion Zh
Page 503 and 504:
Hall effect sensors In opposition t
Page 505 and 506:
Crack Detection using Pulsed Eddy C
Page 507 and 508:
Fig. 1 (a) ARMANDA - Automated scan
Page 509 and 510:
Fig. 2. Images of the Eddy current
Page 511 and 512:
Reading 2: 4.9.2.3 Pulsed Eddy Curr
Page 513 and 514:
Good Luck Charlie Chong/ Fion Zhang
show all

Electromagnetic Testing

Create successful ePaper yourself

Delete template?

Save as template?