N

theNDT Technician

The American Society for Nondestructive Testingwww.asnt.org

Near vision acuity is a subject thathas been addressed in NDTcertification standards for years, yetthe process and purpose ofmeasuring near vision acuity is stillwidely misunderstood. The mostcommon means to measure nearvision acuity for NDT personnel inthe U.S. is to have them read textfrom a standardized reading cardusing either the Jaeger or theSnellen numbering system. Anothersystem, the Point system, uses textin the Times Roman font on a nearpoint chart where each point is0.35 mm (1/72 in.).

Standardized Reading Cards

Jaeger Chart. The Jaeger eye chartis named for Edward Jaeger, whoin the nineteenth centuryintroduced a near point chart withtext divided into sections. The

letter sizes from one section to thenext are incremented from 0.5 mmto 19.5 mm; sections are designatedJ1 to J20. The smallest Jaeger text,J1, subtends the visual angle of fiveminutes, or 1/12 of a degree, at adistance of 0.45 m (17.7 in.).Snellen Chart. The Snellen chart,developed by Herman Snellen, alsoin the nineteenth century, useslower case letters which alsosubtend the visual angle of5 minutes of arc at 0.45 m(17.7 in.). With the Snellentechnique, vision acuity is described

using a fraction d/D, where d is thetest distance and D is the distanceat which the letter subtends5 minutes of arc. For example, if at6 m (20 ft) a person can only reada letter that subtends 5 minutes ofarc at 9 m (30 ft), then the Snellenfraction would be 6/9 (20/30). Asimplistic way to explain this levelof vision is that the person canonly see letters that are at least1.5 times larger [9/6 (30/20)] thanthe smallest letter read by someonewith 6/6 (20/20) vision.

FOCUS

Understanding Near Vision Eye TestsJames W. Houf

FOCUS continued on page 2.

TNT · October 2009 · 11Vol. 8, No. 4

James W. Houf, Senior Manager, Technical ServicesDepartment, American Society for NondestructiveTesting, Columbus, OH 43228. (800) 222-2768,jhouf@asnt.org.

Table 1. Equivalent letter sizes for common near vision acuity tests. The Snellenfractions here are exact. Most Snellen charts using feet are in increments of 5(20/20, 20/25, 20/30, etc.), so the Snellen number is usually rounded to thenearest 5 (20/20, 20/25, etc.).

Eye chart Letter size

Jaeger J1 J2 J3Jaeger viewing distance, cm (in.) 38 (15) 50 (20) 63 (25)

Snellen equivalent, m (ft) 6/7 (20/22) 6/8 (20/27)* 6/12 (20/40)*Times Roman (points) 3.5 (N3.5) 4.5 (N4.5) 6.0 (N6.0)

* Snellen numbers here are equivalent only when viewed at 38 cm (15 in.).

Point Chart. The Point chart uses Times Romantext as noted above. In the United Kingdom, thepoint sizes are preceded by an "N", N5, N6, and soforth. Table 1 shows the relationship between theJaeger, Snellen and Point charts for the smallestthree Jaeger numbers.

Visual Angle

The visual angle is the angle formed by two linesdrawn from the center of the eye lens to thetop and the bottom of one of the vision acuityletters as shown in Fig. 1. As can be seen, bothletters “f ” subtend the same visual angle, butbecause one letter is twice as far away from theeye, its height is actually taller. Thisdemonstrates the fact that if the distance fromthe eye to the object is greater, the letter mustbe taller in order to maintain the same visualangle.As a result, one reading card may use a small

letter at a closer distance while another mayhave a larger letter that must be read at a greaterdistance yet each will be a valid test for thesame vision acuity. Viewing the larger letter atthe closer distance will increase the visual angle,and conversely, viewing the smaller letter at agreater distance will decrease the visual angle,and neither would be a valid acuity test sinceboth charts would have been read at anincorrect distance.

The Jaeger Reading Card

Character size (height) on a Jaeger reading card(Fig. 2) will vary with the reading distancespecified on each individual card for a givenacuity.Most cards will have a statement at the bottom

that says something like “the above letters subtendthe visual angle of 5 minutes at the designateddistance in inches.” This statement is printed onthe bottom of the Western Optical® reading cardsnow published by Western Ophthalmics and soldby ASNT. The height of letters on reading cardswill vary depending on the reading distancespecified on the individual card. There is usually aset of numbers down the center of a card, one foreach Jaeger size, and that is the distance at which

AASNT’s Technical Services Department receives many calls throughoutthe year concerning the proper use of eye charts as a means ofmeasuring near vision acuity. “Near Vision Eye Tests” provides anin-depth explanation of some basic concepts of vision testing anddiscusses three standardized reading cards as well.

The relationship between an NDT inspector andwelders is sometimes laden with more than averagepotential for misunderstandings. In our “PractitionerProfile,” structural steel inspector Timothy Crickexplains that both a working knowledge of weldingprocesses and finding and fairly evaluatingdiscontinuities can go a long way in building andmaintaining a good reputation among welders.

In 2005, researchers for the AntikytheraMechanism Research Project used enhanced visual testing techniques andmicrofocus computed tomography to unravel an ancient puzzle. Thenondestructive tests were used to examine the remnants of an ancientdevice recovered from a Roman ship that sank more than two thousandyears ago near the tiny Aegean island of Antikythera

Hollis Humphries, TTNNTT EditorPO Box 28518, Columbus, Ohio 43228; (800) 222-2768 X206;

fax (614) 274-6899; e-mail <hhumphries@asnt.org>

22 · Vol. 8, No. 4

FOCUS continued from page 1.

FROM THE EDITOR

TTeecchh TToooonn

that size text is to be read to meet therequirement for that Jaeger number. Atthat distance, the letters will subtend thevisual angle of five minutes. Five minutesis the standard visual angle used formost reading cards.

Distance for Reading Test

As noted above, using a Jaeger readingcard at other than the distancespecified for the given text size will

cause the results to be inaccurate.Similarly, Snellen 20/22 and 20/25 arejust that; one cannot be said to beequivalent to another because they arenot. Again, a specific distance shouldbe used for the chart that is used, andthat distance should be specified onthe card or chart.If you check two different reading

cards, you may find that the specifieddistances vary. The taller letters should

specify a greater reading distance; thedistance at which the card is to beread changes with the font size. Usingthe card at other distances will lead toa false eye test.Because many specifications state

that near distance vision acuity shallbe J1 (or J2) "at a distance of not lessthan 12 inches," many people believethat they can move the reading card into 300 mm (12 in.) and they will get aJ1 or J2 eye examination. This is notso; the text selection must be read atthe appropriate distance as specifiedon the card.Most NDT certification documents

don't specify a near vision acuity testat 300 mm (12 in.); they usually statethat the test is “not to be given at lessthan 12 inches.” This statement wasintended to prevent the use of smallerreading cards that might specify areading distance less than 300 mm(12 in.) This prohibits the use ofminiature reading cards (some the sizeof business cards) that have specifiedreading distances less than 300 mm(12 in.). To clarify this in the 2006edition of Recommended PracticeNo. SNT-TC-1A, the text inparagraph 8.2.1 was changed to read,“... the applicant is capable of readinga minimum of Jaeger Number 2 orequivalent type and size letter at thedistance designated on the chart butnot less than 12 inches (30.5 cm) on astandard Jaeger test chart.” The boldtext is added for emphasis here toensure that the intended use of thecard is understood.1

Jaeger Equivalents

In 2004, when ASNT first began todraft ANSI/ASNT CP-106,Non-destructive Testing — Qualificationand Certification of Personnel2 (the U.S.adoption of ISO 97123), the phrase

TNT · October 2009 · 33

FOCUS continued on page 5.

Figure 1. The concept of visual angle. From different distances, letters of differentsizes may subtend the same visual angle. In terms of vision acuity, they areeffectively the same size if read at the appropriate distances.

Visual angle

Eye lensx

2x

J1 designation forsmallest text size

Corresponding readingdistance for J1 text

Chart must be held atdistance that corresponds

with text groupbeing read

Figure 2. The Jaeger eye card is widely used for performance examinations ofnear vision acuity. Text groups gradually increase in size and are designated as J1,J2 and so on. The vision acuity equivalent of each Jaeger designation depends onthe distance at which the chart is held. This image has been scaled andprocessed for publication and must not be used for vision examination.

“or equivalent” was used in the nearvision acuity section. Because"equivalent" values were not given, theASNT Technical Services Departmentreceived numerous calls asking forclarification of what was consideredequivalent to the various Jaegernumbers, so the StandardsDevelopment Committee (SDC),ASNT’s consensus committee fordeveloping American NationalStandards, was asked to include a noteregarding equivalents to clarify whatwould be accepted. The committeeagreed. To determine “equivalency,”the following organizations werecontacted:

1. for Snellen values and TimesRoman points, the AmericanOptometric Association, theNational Optometric Association,The Ohio State University Collegeof Optometry and several localoptometrists;

2. for OrthoRater® values, theOphthalmic Division that passedfrom Reichert, Inc., to Bausch &Lomb and Leica-Microsystems;

3. for Titmus® values, theBacou-Dalloz Company (nowSperian).

On Items 2 and 3, both companiesgave the values listed in CP-106. Onitem 1, many of the responses to ourinquiries referred us the handbook foroptometry, Clinical Refraction, by IrvinM. Borish.4 Dr. Timothy Wingert,then Acting Director of the ClinicalCare Group of the AmericanOptometric Association, providedspecific page and chapter referencesfrom the 1975 edition of ClinicalRefraction, pointing out that while thisedition is out of print,5 the data are

still valid, and he provided thecomparative information shown inTable 1. Because most optometristsrecord values in even numbers, 6/6(20/20) is usually accepted for J1 and6/7.5 (20/25) for J2, but a companyshould consider describing whateverconvention they choose to use in theirwritten practice, remembering thatacceptance of a certification programis a matter of agreement between theNDT supplier and purchaser.

Disclaimer

The information in this article isprovided for instructional purposesand is not a statement of ASNTpolicy or practice.

References

1. Recommended PracticeNo. SNT-TC-1A, PersonnelQualification and Certification inNondestructive Testing. Columbus,OH: American Society forNondestructive Testing (2006).

2.ASNT CP-106 (national adoptionwith modifications of ISO 9712),Nondestructive Testing —Qualification and Certification ofPersonnel, third edition. Columbus,OH: American Society forNondestructive Testing (2008).

3. ISO 9712, Non-Destructive Testing— Qualification and Certification ofPersonnel. Geneva, Switzerland:International Organization forStandardization (2006).

4. Borish, Irvin M. Clinical Refraction,third edition. Volume 1. Chicago,IL: Professional Press (1970, 1975):pages 391 and 418.

5. Borish’s Clinical Refraction, secondedition. St Louis, MO: ButterworthHeinemann (2006).

TNT · October 2009 · 55

FOCUS continued from page 3.

Near Vision Acuity

equivalent 20/20 near visionacuity: Vision acuity withremote viewing or other indirectviewing that approximates20/20 direct viewing closelyenough to be considered thesame for visual testing purposes.

far vision: Vision of objects at adistance, generally beyond arm’slength.

jaeger eye chart: Eye chart usedfor near vision acuityexaminations.

near vision: Vision of objectsnearby, generally within arm’slength.

vision acuity: Ability to distinguishfine details visually.Quantitatively, it is thereciprocal of the minimumangular separation in minutes oftwo lines of width subtendingone minute of arc when thelines are just resolvable asseparate.1,2

vision: Perception by eyesight.visual angle: Angle subtended byan object or detail at the pointof observation. It usually ismeasured in minutes of arc.1,2

References

1.Nondestructive Testing Handbook,second edition: Vol. 8, Visualand Optical Testing. Columbus,OH: American Society forNondestructive Testing (1993).

2.IES Lighting Handbook:Reference Volume. New York,NY: Illuminating EngineeringSociety of North America(1984).

NDT GLOSSARY

IIn 1901, Greek sponge divers, blownoff course in a storm, sought refugeby anchoring their ship in the lee ofthe tiny Aegean island calledAntikythera. When the storm abated,one of the crew donned a diving suitand went over the side. It is unclearwhether the diver was looking forsponges or foraging for food but hewas amazed when he found theremains of a shipwreck directly below.Strewn before him was a pricelesstangle of booty. It would eventually bedetermined that the wreckedship was a Roman trader,probably on its way to Rome. Ithad been filled with treasuresfrom Greece. Dates on coinsfrom Pergamum found amongits wreckage showed the shipsank around 80 BC.

The find was reported toauthorities and a majorunderwater recovery expeditionwas mounted by the NationalArcheological Museum inAthens. The recovered artifactswere taken to the museumwhere they reside today. Theitems recovered includedclassical Greek bronze andmarble statuary and even fineglassware. In addition, a lumpof calcified bronze, shoebox-size, waslifted from the seabed. Eventually, itwould come to be known as theAntikythera Mechanism and wouldattract international attention but, atthe time, it seemed relativelyinsignificant and when it reached themuseum in Athens, it was set aside ona shelf. After some time however, thestructure split apart to reveal intricate

gearing inside (Fig. 1). Modernresearch was unaware that mechanicalsophistication of this degree existed inancient Greece. More than a thousandyears would have to pass beforestructures approaching this complexitywould begin to appear again.

What was the AntikytheraMechanism?

Much research has determined thatthe Antikythera Mechanism was adevice to model astronomical

phenomena; its purpose was to linkthe cycles of Greek culture with thecelestial cycles incorporated into itsgearworks. Its highly complex dialsand spirals, gears, and pointing deviceshad the ability to track progressions ofthe sun and moon (and possibly thefive planets known then). It was acalendar and could predict eclipses. Itwas a calculator with the ability to

multiply, divide and subtract. Recentinterpretations of its inscriptions leadresearchers to believe that its originwas in the Corinthian colonies ofnorthwestern Greece, or possiblySyracuse in Sicily. Although the devicehad puzzled academics and scientistsfor more than a hundred years, studyof the apparatus did not gain impetusuntil the 1950s and 60s. In the early1970s various kinds of imaging,including X-ray, were done.

The mechanism housing had afront door plate withinscriptions. The front of themechanism itself also includedmany inscriptions and a devicefor showing the positions of thesun and moon. Internal gearingfor the apparatus was formedfrom bronze sheet(approximately 2 mm thick).The back of the structure hadan upper and lower dial as wellas additional inscriptions.Significantly, the AntikytheraMechanism is dated by itsinscriptions. Greek script variedconsiderably during the periodwhen the mechanism wasmanufactured. The structure ofthe letters in the inscriptionsand the way they are put

together in sentences make it possibleto date it quite accurately. It isrelatively certain that it was made atend of the second century BC —140 to 100 BC.

Formation of the AMRP

Lead by astronomer Mike Edmunds,Professor in the School of Physicsand Astronomy at Cardiff University

Visual Testing and X-Ray Used to Examine AntikytheraMechanism

Insight

66 · Vol. 8, No. 4

Figure 1. Largest fragment of Antikythera Mechanismshown in natural light. © Antikythera ResearchMechanism Project.

in Wales and mathematician TonyFreeth, a freelance producer anddirector working in television andindependent production of scientificdocumentaries, the AntikytheraMechanism Research Project (AMRP)was formed to collect new primarydata on the device. In late 2005,permission to carry out proposedinvestigations was granted andstate-of-the-art technology wasrecruited to probe the interiors of theAntikythera Mechanism usingenhanced digital imaging techniquesdeveloped by Hewlett Packard Labs inPalo Alto, California and microfocuscomputed tomography (CT)developed by X-Tek Industries (nowMetris) in Hertfordshire in the U.K.

Reflectance Imaging Techniques

The Antikythera Research Projectinvited Hewlett Packard Labs researchscientists to Athens to applyreflectance imaging to the front andrear surfaces of the more than70 fragments that comprise themechanism. The noninvasivetechnique involves taking photos ofan artifact from a fixed point while

using 50 different light sources arrayedin a hemisphere or dome placed overthe object (Fig. 2). The light sourcesfire in succession and the cameraregisters them individually. Softwarecan then be used to tie the imagestogether. In effect, this enables thearchaeologist to change the angle oflight or texture of the surface of theobject to make faint markings appearmore vivid. It’s as though the objectbeing investigated can be held andmoved around. Originally developedfor looking at indentations onpapyrus, the technique is a very goodway of discerning very subtle surfacedetail. In addition, reflectance imagingcan be used to digitally manipulate thesurface quality of an object toenhance its detail. Dull surfaces can bemade to look shiny, for example(Fig. 3).

Microfocus ComputedTomography

A major expedition brought the400 kV microfocus computedtomography machine – weighing morethan 7.5 metric tons – to examine theartifact in Greece. Originally designedby X-Tek Industries to search forimperfections in turbine blades,printed circuits and other industrial

devices, the machine creates detailedthree-dimensional X-ray images. It wasoriginally thought thatthree-dimensional CT results wouldprove most useful by producing goodimages of the gear train. This wouldallow researchers to obtain accurateteeth counts for the mechanism’sgears, thereby resolving argumentsregarding relationships between thegears. However, it came as surprisewhen investigators realized how wellthe machine was able to imageinscriptions inside the fragments ofthe apparatus (Figs. 4, 5). It wasexpected that some faint inscriptionswould be revealed butthree-dimensional CT not only

TNT · October 2009 · 77

Figure 2. Researchers demonstratedomed structure used to photographobjects under varying light conditions.© Hewlett Packard Laboratories.

Figure 3. Photos of AntikytheraMechanism fragment show how thedevice appears under conventionallighting and how surface features areenhanced by use of reflectanceimaging. © Antikythera MechanismResearch Project.

Figure 4. Three-dimensionalcomputed tomography scans resultedin high-resolution digital radiographsthat revealed textual and other details.© Antikythera Research MechanismProject.

INSIGHT continued on page 8.

Figure 5. Digital radiographs obtainedwith three-dimensional computedtomography allowed researchers tofollow impression of inscriptions downinto fragment surface. © AntikytheraMechanism Research Project.

allowed researchers to see theinscriptions, it made them muchclearer by allowing researchers tofollow the impressions of thecharacters down into surfaces andthus beneath corrosion. The CTimages, from various angles, enabledthe research project to read 932characters, far more than any previousattempt.

Conclusion

The mechanical complexity of theAntikythera Mechanism implies atechnological tradition; one in whichits builders were accustomed toworking with gears and figuring outhow mechanisms were made. When itwas built, bronze was both extremelyvaluable and difficult to produce. It’spossible that devices such as thesewould have been melted down whenthey stopped working, lost theirnovelty or people forgot how to usethem. Still, we are left to wonder whathappened to the rest of thetechnology and how it all was lost.

Bibliography

1. Antikythera Mechanism ResearchProject. <http://www.antikythera-mechanism.gr/>.

2. X-Tek Group (now Metris).Hertfordshire, United Kingdom.<http://www.xtekxray.com/applications/antikythera.html>.

3. Hewlett-Packard Laboratories.<http://www.hpl.hp.com/research/ptm/antikythera_mechanism/index.html>.

4. Freeth, T., Y. Bitsakis, X. Moussas,J. Seiradakis, A. Tselikas, E.Maglou, M. Zafeiropoulou, R.Hadland, D. Bate, A. Ramsey, M.Allen, A. Crawley, P. Hockley, T.Malzbender, D. Gelb, W. Ambriscoand M. Edmunds. “Decoding theAncient Greek AstronomicalCalculator Known as theAntikythera Mechanism.” Nature.Vol. 444, No. 30. London, UnitedKingdom: Nature Publishing

Group (November 2006):p 587-591.

5. Seabrook, J. “FragmentaryKnowledge.” The New Yorker.New York, New York: Conde NastPublications (May 2007) p 94-102.

6. Freeth, T., A. Jones, J. Steele and Y.Bitsakis.. “Calendars withOlympiad Display and EclipsePrediction on the AntikytheraMechanism.” Nature. Vol. 454,No. 30. London, United Kingdom:Nature Publishing Group (July2008) p 614-617.

88 · Vol. 8, No. 4

INSIGHT continued from p 7

Got a topic for “Working Smarter”? Ifpublished, you can earn $50 in cash ora $75 credit for ASNT merchandise.Contributors to TNT also earn recertpoints in the following programs:

• ACCP Level II,• ACCP Professional Level III and• ASNT NDT Level III.

A full article of 1000+ words earnsthree points; short articles or items for“Working Smarter” earn one point.Contact the TNT Editor:

PO Box 28518, Columbus, OH 43228(800) 222-2768 X206;

(614) 274-6899 fax<hhumphries@asnt.org>

TNT · October 2009 · 99

4. Liquid that enters cracks.6. Instrument measuring UV light intensity.8. Light used at fluorescent penetrant wash station.10. Specification compliance document.11. Aerospace known defect test piece.12. Passive penetrant process activity.16. Instrument measuring aqueous developer concentration.

17.Method D processingstep that precedesemulsifier.

18.Approved penetrantmaterials are listed onthe ___.

19.Penetrant flow rate.21.Developer in spray can.22.Tool for measuring

viscosity.23.Sound wave cleaning.27.Processing step following

penetrant dwell.28.Method B and D

penetrant and emulsifierare approved as a ______.

31.Black light output.

Across3. Emulsifier diluted with water.5. Early user of oil and whiting.7. Highest sensitivity level for fluorescent penetrants.9. Materials lot identification number.12. Parts for penetrant inspection must be clean and ___.13. Unit for measuring ultraviolet intensity per square centimeter.14. Instrument measuring

Method D emulsifierconcentration.

15. Abbreviation forsolvent suspendeddeveloper.

17. Instrument measuringwhite light intensity.

20. Method B emulsifier.24. A penetrant test kit is

used for _____testing.

25. The Karl Fischeranalysis tests for_____ content.

26. Document describingany hazards.

28. Device used tomeasure fluorescentbrightness.

29. Method C remover.30. Penetrant requiring darkened area for inspection.32. Static charge spray application method.33. First thing you must do with an aerosol can of developer.34. Forms A, B and C developers are supplied as ______.35. Step preceding application of penetrant.

Down1. Form B and C developers are applied before ______.2. Method A remover.

Across

3.hydrophilic5.railroad7.four9.batch12.dry13.microwatt14.refractometer15.NAD17.photometer

20.lipophilic24.field25.water26.MSDS28.fluorometer29.solvent30.fluorescent32.electrostatic33.shake34.powder35.preclean

Down

1.drying2.water4.penetrant6.radiometer8.ultraviolet10.certification11.TAM12.dwell16.hydrometer

17.prerinse18.QPL19.viscosity21.nonaqueous22.viscometer23.ultrasonic27.removal28.family31.UVA

Crossword ChallengeLLiiqquuiidd PPeenneettrraanntt TTeessttiinnggLLiiqquuiidd PPeenneettrraanntt TTeessttiinnggTThhee PPeenneettrraanntt PPrrooffeessssoorr**

Crossword Challenge

* Michael White and William Mooz, Met-L-Chek Company, 1639 Euclid Street, Santa Monica,California 90404; phone (310) 452-4046; fax (310) 452-4046; e-mail info@me-l-chek.com.

Answers

1

5

2

7 8

15

20

24 25

28

30 31

33

18

16

23

21

19

9

14

10 11 12

6

13

17

22

26

29

27

32

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35

3 4

PRACTITIONER PROFILE

1100 · Vol. 8, No. 4

WWhile the working relationship between an NDT inspector and awelder can sometimes be problematic, Timothy Crick demonstratesthat a good inspector with a proven record of finding and fairlyevaluating discontinuities can build and maintain a goodreputation among the welders whose work he inspects.

Q: How did you get started in NDT?

A: In the early 90s, I worked as a welder for a pipelinemanufacturer up in northern California doing flux corearc welding and dual wire submerged arc welding. I’vealways wanted to learn everything I could and when theyasked if I wanted to become an inspector I said yes.

Inspectors, if laid off, will get a job somewhere else, soemployers are reluctant to lay them off. So, number one,there was definitely better job security and, number two, Iwanted to lean more than welding. The firm I wasworking for did UT and RT inspections and I became alevel II in both. Our company Level III, Mr. CharlesHanson, performed all of our training and certification.

Q: Tell us about your NDT experience to date.

A: I left northern California and moved to San Diego whereI worked for a one-man company. We did everything fromNDT in Navy and commercial shipyards to welder andprocedure qualifications. From there, I actually took twojobs. One was eight hours a day and the other was asmany hours as I could fit into the rest of the day. I was

inspecting aircraft parts in the aerospace industry but thatonly needed my X-ray Level II working experience. I reallyenjoy doing UT and I couldn’t pass it up when somebodyneeded me to do what I’m doing now —ultrasonic testingon commercial buildings. So I kept both of mycertifications going by doing both. Each form ofinspection is totally different. I get dirty and climb all overbuildings in one and I sit in a clean room interpreting filmin the other. My next job was with an independent lab inTexas where I did NDT in aerospace, oilfields, powerplants, and even in the amusement park industry. I got todo different types of ultrasound there that I had only reador heard about, such as through-transmission inspecting747 parts that were as big as a car. Inthrough-transmission, there are two transducers facingeach other at a set distance apart. One transducer sendsand the other receives. A stream of water aimed at each ofthem is used as the couplant. If there are any indicationswithin the part, you have a loss of sound. I also leaned todo mag particle and became certified in that method.

Q: What are your current certifications?

A: I am currently certified as a Level II in UT, RT, MT, andPT. I’ve also done ET, but not for many years.

Q: What was your educational background before you begantraining in NDT?

A: My education was high school. I did learn mechanics inthe air force. I’ve always had a technical background andhands-on is where I excel. I love the hands-on experienceand that’s definitely what NDT has been. I’ve inspectedparts that went five miles underground and parts that arefloating right now on the international space station. Thatgives me a rewarding feeling.

Q: What kind of structures do you inspect now?

A: I’m inspecting welds in structural steel on the biggesthospital project ever in the state of California — momentconnections — mainly beam splices and column splicesusing UT and MT.

Timothy Crick

“It’s not my job toadvise the weldersbut at the same time,our common goal isto complete anacceptable product.”

TNT · October 2009 · 1111

Q: Is phased array any part of that?

A: I’ve only had limited observation of phased array but notits actual use. I understand its benefits and it’s something Iwill be getting in the future.

Q: How does your experience as a welder help you whenconducting inspections?

A: It helps me understand the indications or thediscontinuities that I find. It also makes it easier for me tohelp the welder understand problem areas so that we canreduce the number of discontinuities and rejects. It’s notmy job to advise the welders but at the same time, ourcommon goal is to complete an acceptable product. Myexperience has taught me that it’s much better to have aweld done right the first time than to have to go back andhave it fixed.

Q: As an NDT inspector, how do you maintain a productiverelationship with the people that do the work you inspect?

A: Some inspectors out there have a bit of a power issue andsome couldn’t care less if the welder continues to getrejects. My approach is to let them know that I’m there tohelp. I also let them know that I have previous welding

experience so that they might be able to relate to mebetter.

Q: Do you see that your efforts reduce the number of rejects?

A: Definitely.

Q: What’s the best part of your job?

A: The best part of my work is the people — people thatI’ve had the opportunity to learn from and work with.

Q: What’s the worst part?

A: I think the hardest part has been when I had to workaway from home, away from my family.

Q: How would you advise someone considering an NDT career?

A: Try to work for good people. I’ve found that the bestpeople to work for are those that raise the bar. Earlier Ithrew out Charlie Hanson’s name. Charlie worked in thepipeline industry with codes and specs that didn’t requirehigh quality but he took his prior work experience andused it to raise the standards in the pipeline industry.

You can contact Timothy “TC” Crick by e-mail,<tcrick4152@yahoo.com>.

the NDT Technician

Volume 8, Number 4 October 2009

Publisher : Wayne Holliday

Publications Manager : Tim Jones

Editor : Hollis Humphries

Technical Editor: Ricky L. Morgan

Review Board: W illiam W. Briody, Bruce G. Crouse,Anthony J. Gatti Sr., Edward E. Hall, James W. Houf, JocelynLanglois, Raymond G. Morasse, Ronald T. Nisbet, AngelaSwedlund

The NDT Technician: A Quarterly Publication for the NDT Practitioner(ISSN 1537-5919) is published quarterly by the American Society forNondestructive Testing, Inc. The TNT mission is to provide informationvaluable to NDT practitioners and a platform for discussion of issuesrelevant to their profession. ASNT exists to create a safer world by promoting the profession andtechnologies of nondestructive testing.Copyright© 2009 by the American Society for Nondestructive Testing, Inc. ASNT isnot responsible for the authenticity or accuracy of information herein. Publishedopinions and statements do not necessarily reflect the opinion of ASNT. Products orservices that are advertised or mentioned do not carry the endorsement orrecommendation of ASNT.

IRRSP, Materials Evaluation, NDT Handbook, Nondestructive Testing Handbook,The NDT Technician and www.asnt.org are trademarks of The American Society forNondestructive Testing, Inc. ACCP, ASNT, Level III Study Guide, Research inNondestructive Evaluation and RNDE are registered trademarks of the AmericanSociety for Nondestructive Testing, Inc.

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Q:Where can I get an ASNT certification application?

A:All ASNT certification applications can be found on ASNT’s Web site athttp://www.asnt.org/certification/certification.htm.

Q:Where can I find ASNT’s exam schedules?

A:ASNT exam schedules can be found athttp://www.asnt.org/certification/schedules/index.htm.

Q:How long does it take to get exam results?

A: Examination results are mailed within four to six weeks for those residing in theUS or Canada. Results for candidates living outside the US may take one to twoweeks longer. Exam results cannot be given over the phone or via e-mail.

Q:How long does ASNT certification remain valid?

A:ASNT certification remains valid for five years.

E-mail, fax or phone your questions for “Inbox” to the Editor:hhumphries@asnt.org, fax (614) 274-6899, phone (800) 222-2768 X206.

INBOX