the ndt techniciana quarterly publication for the ndt … · 2011-03-13 · crossword challenge:...

In August of 2006, a major petroleumcompany experienced the second loss ofcontainment incident within the year onthe pristine and environmentally sensitiveNorth Slope of Alaska. Both leaks resultedfrom internal pitting corrosion on or nearthe bottom half of 0.85 m (34 in.)diameter transit pipelines. These linestransport 400 000 barrels of petroleum perday across 11 miles of Alaskan tundra.

The failure meant an immediateshutdown of approximately three percentof the petroleum supply to the lower48 states. The potential for environmentaldisaster and the ensuing shutdown werequickly brought to the attention ofenvironmental groups and jurisdictionalauthorities and, as quickly, to theattention of national media. Americanswatched as the balance of environmentalresponsibility and energy dependencecame to rest on the nondestructive testing(NDT) community. This article describesthe investigation and application offast-screening NDT techniques to ensurepipeline integrity and increase inspectionefficiency.

Background

After shutdown, the U.S. Department ofTransportation (USDOT) issued a legallybinding Corrective Action Order (CAO)that mandated exclusive use ofautomated UT to examine the 4 to8 o’clock sectors (radially designated) ofall pipelines throughout the petroleumtransit system. Inspection with UT wouldrequire the removal of polyurethaneinsulation panels and preparation of pipe

surfaces throughout the system. Amachine applied anti-corrosion tapecoating half of the pipeline createdfurther difficulty. The number ofinsulation workers and ultrasonictechnicians needed to accomplish theremoval and inspection tasks was initiallythought to be beyond what the NorthSlope could provide for in terms oftemporary housing and travel logistics. Atits height, NDT work alone would require108 UT technicians working in alternating12 h shifts.

The task before the petroleumcompany inspection team was toinvestigate alternative NDT corrosionscreening techniques that could besubmitted to the USDOT for possible

modification of the standing CAO. Thefast-screening NDT techniques neededwould have to detect 50% wall loss insidesurface pits at a 3:1 aspect ratio. Theconsequences of another failure required100% probability of detection (POD) ofany discontinuity that met or exceededthe criteria.

Ultrasonic Method

During the inspections, UT wasacknowledged as the only NDT methodthat could measure absolute remainingwall thickness within localized corrosionareas. All other methods were consideredscreening techniques subject to ultrasonicvalidation and measurement.

Each pipeline was segmented into0.3 m (1 ft) inspection intervals, creatingapproximately 52 000 discrete areas to bescreened for corrosion. Areas with lessthan 25% wall loss were ultrasonicallytested to record minimum and averagewall thicknesses within the segment. Theteam of 108 UT technicians inspected anaverage of 283 segments per day.Automated UT rates were 4.5 to 6.0 m

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Volume 6, Number 3 July 2007

Focus: Alternative NDT Techniques for Prudhoe Bay Pipeline Failures . . . 1

From the Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Tech Toon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Feature: Microbiologically Induced Corrosion . . . . . . . . . . . . . . . . . . . . . . 7

Practitioner Profile: Joshua Jones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Inbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Crossword Challenge: Materials and Processes – Part I . . . . . . . . . . . . . . 10

A Publication of the American Society for Nondestructive Testing

FocusAlternative NDT Techniquesfor Prudhoe Bay PipelineFailuresby John J. Nyholt

CONTENTS

The NDT Technician A Quarter ly Publ icat ion for the NDT Pract it ioner

Focus continued on page 2.

(15 to 20 ft) per crew, per shift — unusuallylow, requiring additional manual scanning.Unlike automated UT, manual UT providesno ultrasonic image or permanent record ofthickness measurement. Unless a successfulalternative NDT technique could be foundand accepted by the USDOT, the inspectionof 52 000 areas was going to take 184 days.

Neither manual nor automated UT in itscurrent configuration could inspectremaining wall thicknesses at welds,supports, or anchor points. Internalcorrosion in these areas, however, was notconsidered preferential and inspection ofthem was deferred to the intelligent pig(robotic pipeline inspection gage insertedinto the line) run that would follow externaltests.

Axially orientated electromagneticacoustic transducer (EMAT) technology wastrial tested for pipe support touch pointcorrosion and was determined to detectgreater than 30% wall loss from 0.5 m(20 in.) away from the support.

Tape stripping was later suspended inlieu of performing automated UT through4 mm (0.16 in.) thick anti-corrosion tape,8 mm (0.31 in.) at overlaps (Fig. 1).Ultrasonic performance on tape wrappedpipe was found to be fully equivalent tobare pipe inspection provided the tape wasbonded and uniform. Areas where the tapewasn’t properly bonded were infrequentand were marked for tape removal andreinspection with automated UT. Absoluteultrasonic thickness measurements could beobtained by applying time of flight (TOF)delay correction factors of –10 mm(–0.39 in.) for single tape layers and –23 mm(–0.91 in.) for double tape layers. Ultrasonicecho-to-echo coating compensation modewas not used; pitting responses couldinterfere with proper UT signal gating.Ultrasonic testing amplitude sensitivity wasestablished by 6 mm (0.25 in.) flat bottomhole (FBH) response on a bare calibrationblock followed by an applicable dB transfervalue.

2 · 07/2007 · The NDT Technician

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FROM THE EDITOR

J ohn Nyholt’s article, “Alternative Techniquesfor Prudhoe Bay Pipeline Failures,” describesthe inspection of two transit pipelines

crossing 11 miles of ecologically fragile tundrain Prudhoe Bay, Alaska as “a balance betweenenvironmental responsibility and energy dependence.”Indeed, the two lines deliver 400000 barrels of crudepetroleum daily but within a tenuous eco-systemwhere extensive and permanent damage can be doneshould petroleum leaks occur. Interior surfaces of thepipelines had become severely compromised, in someplaces, as much as 70 to 80% of wall thickness hadbeen lost. As an NDT Corporate Level III InspectionSpecialist, Nyholt’s job, along with the companyCorrosion, Inspection and Chemicals Team, was to findand implement alternate NDT techniques to quicklyand accurately detect the USDOT mandated 50% wallloss with 100% probability of detection. As he explains,it was a concerted effort from all members of the NDTcommunity that resulted in positive outcome for boththe environment and energy consumers.

Hollis Humphries, TNT EditorPO Box 28518, Columbus, Ohio 43228

(800) 222-2768 X206; fax (614) 274-6899<[email protected]>

Focus continued from page 1.

... AND THAT WOULD BE ONE OF OUR TRAINEES.

Tech Toon

Figure 1. Automated ultrasonic testing imageof isolated pit made through single anddouble layers of anti-corrosion tape .

Isolatedpit

Single layerof tape

Double layerof tape

Alternative NDT Corrosion Screening

Alternative corrosion screeningtechniques to complement or replaceultrasonic techniques had to maintaindiscontinuity detection thresholds whileincreasing NDT production tenfold. Allcommercial techniques were consideredfor application but, because of the highlyisolated nature of material damage in thepetroleum transit lines, the extremeconsequences of another failure, and theinspection opportunities afforded bycomplete removal of the polyurethaneinsulation panels, only those techniquesusing a small, localized energy field werechosen. Real time data analysis was also aconsideration as was the need tominimize further preparation of pipesurfaces.

At the end of preliminary assessments,four electromagnetic techniques werefavored for fast screening of isolatedpitting. Electromagnetic techniques donot require direct surface coupling, allowfor real time inspection of large areaswithout labor-intensive surfacepreparation, and can speed up inspectionwithout sacrificing test sensitivity or dataquality. Of the four techniques consideredas automated UT alternatives, only twowere selected as short-term solutions.EMAT. Electromagnetic acoustictransducers (EMATs) use a permanent orelectromagnetic driver/coil arrangement

to create various ultrasonic wave modeswithin carbon steel. Figure 2demonstrates compression wave mode. Inguided wave UT mode, EMAT typicallygenerates a 5 cm (2 in.) wide sound beamthat averages material volume anddetects localized wall loss across the spanof two permanent or electromagneticdriver/coil sensors. A mechanized scannermoves axially at a scan rate of roughly 75to 150 mm (3 to 6 in.) per second.LFET. Low frequency electromagnetictesting (LFET) uses an electromagneticdriver/coil arrangement to createmagnetic lines of flux through the volumeof carbon steel material. Corrosion causeschanges to nominal conditions of thefield. Signals produced by these changesare received by a pickup coil measuringmagnetic flux amplitude and phase(Fig. 3). EMAT technology is wellestablished in industry and recognized inASTM document E 18161 whereas LFETtechnology is newer. Similar to magneticflux leakage in its sensor arrangementand usage, it offers electronic phaseanalysis and intuitive data interpretation.

Technique Trials

Performance of EMAT and LFETequipment was assessed under actualfield conditions. A meticulous effort wasmade to disregard expectations based onpreconceptions or manufacturer’s data.The 0.75 m (30 in.) decommissionedpipeline selected for trials was subjected

to preliminary testing with intelligentpigging to provide known pittingcorrosion areas for study. Computedradiography provided images of pitting.Ultrasonic thickness measurements withtape coating thickness compensationprovided pit depth and aspect ratioinformation. A wide range of pit sizes,depths and morphologies were used toestablish discontinuity depth detectionthresholds and minimum detectectablediscontinuity aspect ratios for eachmethod (Figs. 4-7).

Field Trial Summary

EMAT. Performance attributes for EMATtesting were as follows (Fig. 5): • EMAT demonstrated 100% POD for

25% wall loss isolated pitting at a 3:1aspect ratio in a 9 mm (0.375 in.) pipewall [limited to T2 mode at 0.28 m(11 in.) probe spacing].

• EMAT can detect 30% wall loss at a4:1 aspect ratio in a 9 mm (0.375 in.)pipe wall wrapped with anti-corrosiontape.

• Ten percent of anti-corrosion tapewrapped EMAT indications were falsepositives. False positives are notdetrimental to the POD of EMATtesting but require rework with otherNDT techniques.

• EMAT is susceptible to attenuation (aswith all guided wave UT) with falsecalls due to outside or inside surface

07/2007 · The NDT Technician · 3


Figure 2. Diagrams contrasting compressionwaves generated by (a) conventionalultrasonic testing with couplant and(b) waves generated by electromagneticacoustic transduction.

(a)

(b)

Crystal

Couplant

Crystal

EMAT coilcircuit

Magnetic field

Ultrasonicwave

Ultrasonic wave

Lorentzforce

Eddycurrent

Carbonsteeltest

object

Carbonsteeltest

object

Figure 3. Electromagnetic driver creates(a) magnetic flux lines that reflect thenominal condition of a volume of steel withno discontinuities and (b) flux lines thatdeviate from the nominal condition toindicate a discontinuity.

(a)

(b)

Steelplate

Magnetic linesof flux

Driver

Sensor

Steelplate

Discontinuity

Sweepdirection

Sweepdirection

Figure 4. A typical example of corrosionpitting as it appears in (a) a computedradiographic image and (b) the samepitting example as it appears in anautomated UT image made throughanti-corrosion tape (68% wall loss).

(a)

(b)


boundary conditions. Internal sludgemay deaden EMAT responses.

• A two-man crew using EMAT caninspect 300 m (1000 ft) per day, 150 m(500 ft) per day on tape wrappedpipe.

• EMAT provides a permanent image ofthe entire inspection segment.

• EMAT Indications must be followed upwith UT thickness measurement.

LFET. The following LFET performanceattributes were noted (Fig. 6):• LFET demonstrated 100% POD for

25% wall loss isolated pitting at a3:1 aspect ratio.

• LFET performance remains unchangedon pipe wrapped with anti-corrosiontape.

• LFET has a false positive overcall rateof less than 1%.

• LFET can verify false positive EMATindications.

• LFET performs better than automated

UT and EMAT on fluorocarbon resinrepair tape.

• Inspection coverage for a two-mancrew using handheld LFET instrumentis limited to 60 m (200 ft) per day.With automation and improved probefixtures, scanning production isincreased to 3 m (10 ft) per min.

• LFET indications must be followed upwith UT thickness measurement.

Field Implementation

After three weeks of NDT production anddevelopment, the performanceboundaries of the alternative NDTscreening techniques were established,although not yet approved by the USDOT.Until this time, hundreds of insulationstrippers, tape scrapers, and ultrasonictechnicians had been workingsimultaneously, around the clock withonly one acceptable surface preparationand inspection technique. Even in August,fatigued workers were enduring workingconditions that included cold, frequentrain, mud and standing water.Anticipating USDOT acceptance of dataalong with formal approval of thetechnology, advance NDT crews began toimplement the alternative NDTtechniques immediately upon approval bythe NDT development team. Trial resultswere presented to USDOT officials and anindependent NDT subject matter expertfrom the U.S. Department of Energy.Many officials (including the U.S.Secretary of Transportation) were inattendance to personally witness NDTtechnicians apply the alternative NDTtechniques in repeated field performancetrials. The alternative techniques wereaccepted by the USDOT and the CAO wasmodified after three weeks.

Pipe Crawler Development

Upon USDOT approval, the company NDTlab in Houston, Texas began work onrobotic multi-channel sensor arrays forLFET and automated UT. Most of the UTand LFET work done to this point hadbeen done by hand. Automated UT hadcontinued to be inefficient. To obtain theneeded tenfold increase in inspectionproduction, further mechanization ofthese techniques was necessary. Deepwater NDE research and developmentprojects already underway at the Houstonlab included LFET and automated UT.Mechanical phases of the projects showedpotential for application at the North

Figure 6. LFET response to pitting sampledescribed in Figs. 4 and 5. Eight line scansbelow C-scan image indicate individualLFET sensor phase angle responses.

Figure 7. Axial scanning automated UTcrawler; (a) closeup of scanner in trial tests,(b) in use on petroleum transit pipeline,and (c) C-scan image of pitting generatedby crawler in trial testing.

(a)

(b)

(c)


Figure 5. Field trial conducted for EMATscanner shows (a) scanner installed on testpipe with pitting example described inFig. 4 and (b) EMAT response to pittingsample (75% wall loss). Red line representsEMAT signal amplitude and blue line istime-of-flight. Saw-tooth pattern indicatestape bonding effects. Flat data segment toright of pitting response represents areawhere anti-corrosion tape was removedfrom pipeline for comparison purposes.

(a)

(b)


Slope site and were hastened into servicein an ambitious three-week pipe-crawlerconstruction program; all other work attwo NDT development firms suspendeduntil the machines could be fabricated.

Figure 7 shows an axial scanningautomated UT crawler capable ofcontinuous ultrasonic imaging of the 4 to8 o’clock sectors of 0.85 m (34 in.) pipe.The two-piece clamshell assembly runsautonomously from pipe support to pipe

support, a distance of about 18 m (60 ft).At which point, the crawler is removedand redeployed in a 5 min. procedure forthe next scan segment. The system runs ata rate of 9.75 m (32 ft) per hour with asingle UT transducer and can increase therate to 30 m (100 ft) per hour byimplementing a four-transducer array anddata merging software. Figure 7c shows atypical automated UT crawler data samplefor a pitted pipe area.

By using an automated UT crawler,NDT technicians could now spend 90% oftheir time monitoring data collectionfrom the comfort of a truck parkednearby. Areas that had been inaccessiblebecause they were over bodies of wateror at extended elevations could now beinspected without scaffolding. Thepotential for injuries or accidents related

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Figure 8. LFET axial scanning array; (a) closeup in trial configuration, (b) in use on petroleum transit pipeline, and (c) LFET data frompipe segment in trial configuration in 8a (compare to C-scan image of pitting in same pipe segment in Fig. 7c).

(a) (b) (c)

to fatigue and exposure was now greatlyreduced.

LFET is highly sensitive to sensor liftofffrom the carbon steel surface yet cantolerate up to 6.35 mm (0.250 in.) innonconductive coatings whilemaintaining discontinuity sensitivity.Figure 8 shows a mechanized160-channel LFET axial scanning arraycapable of continuous and autonomousinspection. Each of the 20 sensor cars isequipped with a separate wheel systemand is spring tensioned into a surfaceconforming array to control liftoff. TheLFET scanner can test 18 m (60 ft) of pipeand provide real time data in just 6 min.

The 50% wall loss 3:1 pit aspect ratiodiscontinuity criteria mandated by theCAO worked in favor of EMAT and LFETscreening tools. Each had a tendency toignore pits below this criterion, thusreducing the time needed for dataanalysis. For example, both the LFET datashown in Fig. 8c and the automated UTdata set in Fig. 7c are from the samesection of pipeline. Only a few of thesepits in the 3 m (10 ft) automated UT scanwere of interest and those showed up inthe LFET scan.

Findings

Necessity drives invention. The dauntingtask of large scale inspection in a remotearea brought many NDT personneltogether with just two goals. Whileunder significant pressure, implement the

NDT techniques that were already knownto work; then come up with new NDTtechniques that could do the job betterand faster. In less than a month, bothgoals had been accomplished. As the newinspection tools were pressed into service,both transit line inspection rates and dataquality steadily improved, as did USDOTconfidence in their ability to perform.The western petroleum transit line wasapproved for production. Three weekslater, the eastern petroleum transit linewas returned to service. Despitechallenging workloads and difficult livingconditions, NDT technicians and NDTengineers had presented a concertedeffort. The open discussion and freeexchange of ideas had facilitatedsolutions for the set of problems thatappeared with each new day andultimately to the timely andenvironmentally responsible restorationof a vital natural resource (Fig. 9).

REFERENCES

1. ASTM E 1816, Standard Practice forUltrasonic Examinations usingElectromagnetic Acoustic Transducers(EMAT) Techniques. WestConshohocken, PA: ASTMInternational (2002).

John J. Nyholt is an NDE Corporate Level III,Inspection Specialist for BP North America. Inconjunction with the BP Corrosion, Inspection, andChemicals Team, he was the BP NDE Subject MatterExpert tasked with investigating alternative NDTcorrosion screening techniques at Prudhoe Bay, AKin 2006. He also teaches NDT at San Jacinto Collegein Houston, Texas (281) 366-2933,<[email protected]>. TNT

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Dear TNT Readers,Do you know what a UT level IIneeds to learn to get up to speedwith phased array UT? Are youproficient in the use of shims andstrips in magnetic particleinspection? Do you know how filmand digital RT are different and thebest application of each? Can youtell us about the envelope method ofdiscontinuity sizing from API 5UE,or how to use acoustic emission inweld testing?

These are topics TNT would like youto write about. Consider becoming aTNT contributor. We’re an officialjournal of ASNT and as such, canoffer you recert points for yourcontribution. Three points perpublished paper.

Contact the TNT Editor:

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

(614) 274-6899 fax<[email protected]>

Figure 9. Petroleum transit pipelines at Prudhoe Bay cross 11 miles of eco-sensitiveAlaskan tundra. The eastern and western transit lines deliver a total of 400 000 barrels ofNorth Slope crude petroleum to the lower 48 states on a daily basis.




C orrosion stems from many causesand myriad variables affect therate at which it occurs, especially

where microbiologically inducedcorrosion (MIC) is concerned. Howquickly and where in pipelines this typeof corrosion will occur is particularly hardto predict. Engineers and scientists haveconducted studies of corrosion tomeasure and model it. However,computer modeling isn’t always accurate,and the “smart” pigs that implement themodeling are difficult to calibrate andaren’t really so smart.

Metabolic Activity

Microbiologically induced corrosionresults from the metabolic activity ofmicroorganisms, bacteria that causemetals, as well as other materials such asplastic and concrete, to deteriorate.Pitting caused by bacterial attack canusually be characterized by rounded pitswith etched sides, edges, and bottoms(Fig. 1). MIC pits also often have aterraced effect (Fig. 2).

Severity Sometimes Unexpected

Severe MIC is sometimes found inpipelines and process piping systemswhere the amount of corrosion shouldhave been only minimal. It is noticed

especially at the bottom of the linewhere water accumulates or at oil/waterinterfaces (Fig. 3). Microbiologicallyinduced corrosion becomes problematicwhen steels are in constant contact withnearly neutral water that has a pHbetween 4 and 9 and a temperaturebetween 50° and 122°F (10° and 50°C)and is more pronounced if the water isstagnant or slow-moving. MIC is usuallyin the form of pitting corrosion underthese conditions.

Colony Structure

Corrosion causing microbes formcolonies. The outside surface of thecolony is populated with aerobicmicrobes that produce polymers (slime)to attract inorganic material. This makesthe colony look like a pile of mud anddebris. The aerobic organisms on theexterior surface of the colony can use upall available oxygen, giving theanaerobic (absence of oxygen) microbes(sulfate reducing bacteria or SRBs) insidethe colony a hospitable environment,and this permits enhanced corrosionunder the colony. SRB colonies can alsoform deposits that are conducive tounder-deposit corrosion (crevicecorrosion).

Biological action increases the severityof corrosion in steel and stainless alloysas a result of (a) disruption of the films

that form on metals, (b) biologicaldeposits on metal surfaces, and(c) production of corrosive materials suchas H2S from SRBs. While aerobiccorrosion of iron is a chemical process,anaerobic corrosion of iron is linked toSRB activity. This type of microorganismcan exist in diverse environments.Unfortunately, the biomolecularmechanisms for iron corrosion and metalreduction and their connections tocentral metabolism and basal cellularprocesses occurring with SRBs are poorlyunderstood. Though the genome of acommon SRB, Desulfovibrio vulgaris, isproviding insight to the bug’smetabolism for corrosion and inorganiccontaminant immobilization.Additional Information. For moreinformation on microbiologically inducedcorrosion, check the following links:• <www.corrosionsource.com> Click the

Handbook tab.• <http://www.asminternational.org> Pdf

download “Biological CorrosionFailures.”

• <http://octane.nmt.edu/WaterQuality/corrosion/microbes.htm>.

Rod Stanley is owner and CEO of NDEInformation Consultants in Houston, Texas.He is an international expert in tubularinspection and chairs the API Resource Groupon Coiled Tubing. (713) 728-3548;<[email protected]>. TNT

Figure 1. Bacterial attack is usuallycharacterized by rounded pits with etchedsides, edges, and bottoms.

Figure 2. Microbiologically inducedcorrosion pits often have a terraced effect.

Figure 3. Although microbiologicallyinduced corrosion normally occurs at thebottom of the line where wateraccumulates, it has also been detected atthe 3 and 9 o’clock positions, presumably atthe oil and water interface.

FeatureMicrobiologically Induced Corrosion

by Roderic K. Stanley

Not everyone enjoys committee work but Joshua Jones hasa mission. He is a member of the ASNT GPR ad hocCommittee that is working to make ground penetratingradar a unique NDT method. As part of that charge thecommittee is developing a body of knowledge.

What was your first exposure to NDT?

I’ve done construction work in the past and had seeninspectors here and there on jobsites. Just by osmosis, I wasaware of what they did and why. The equipment was

interesting and the work didn’tseem that difficult. So I decidedto pursue it.

How did you obtain training?

I started as an NDT assistant andmy training was pretty much onthe job at first. Then, once Icompleted the training in theCollege of Oceaneering, I wascertified in magnetic particle,liquid penetrant and ultrasonictesting. I’ve also taken RTtraining. The rest has beenthrough my employers. I

currently hold Level II certification in RT, MT and PT and aLevel I in UT.

Why did you choose underwater NDT?

Well, I was going to become a commercial diver justbecause I loved to dive — and I still do. I picked NDT as myspecialty because I was already working in the field as anNDT assistant at the time. I could have picked welder ordiver medic. After graduating, I went to work for variouscompanies as an underwater NDT specialist but soonrealized that spending long hours under the waterweighted down with dive weights and wearing heavyequipment wasn’t going to be for me. I decided to applythe NDT skills I had acquired to regular NDT.

What type of NDT work did you do after leavingcommercial diving?

I went to work as an NDT technician and worked in turnfor several companies doing pretty much the kinds of NDTthat I do now. I did a lot of X-ray on concrete and weldX-ray. One of the companies also did GPR or groundpenetrating radar and that’s where I began to learn thattechnology. But for the most part, we did qualifications of

tanks and welds on tanks. I’ve done a lot of MT, PT onboiler tubes in power plants. I’ve also done a lot of labwork and moved from that to running a penetrant line fora company that did finishing work for aerospace.

What type of NDT do you do now?

I specialize in ground penetrating radar. I’ve worked withalmost all of the GPR machines in use in the industry;primarily on concrete but I’ve also used it to map oututility lines in soil. The technology is easy to understandand apply — like using a giant fish finder. The equipmentsends microwave pulses into the concrete and some of thatenergy bounces, or is reflected, from any inclusions andback to the equipment where it produces a signal shapedlike a hyperbola — a big “pip.” It tells you that the steel orconduit is running at right angles to your scan direction.The goal is to map out all inclusions; steel, plastic conduit— everything the contractor wants to avoid. We’ve doneGPR on bridges to locate post tensioning strapped to thebottom of the bridges and beams and on large commercialstructures before a remodel — even on residentialstructures to confirm sufficient footing and posttensioning. We also use X-ray to inspect concrete. I do RTon welds, some MT and PT and, once in a while, I do ET.

Is your work principally in the field or in a lab?

If needed, I sometimes help out in the lab. The companywhere I work now is a field-testing facility, but does somein-lab — parts inspection, aerospace. We also do welderqual (qualification) for outside companies; testing weldersto make sure they can do their job correctly and that theirwelds are acceptable.

What are your current responsibilities?

I’m still NDT all the way, but I’m considered the facilitiesmanager now. I make sure all our crews have the NDTequipment they need and I’m also in charge of vehiclemaintenance.

Has your ASNT membership been a benefit to your career?

Absolutely, it’s a great way to get to know a reallyinteresting group of people. Learning NDT on your own ishard. The opportunity to share ideas or question moreexperienced members really helps you out.

How involved are you in ASNT?

I attend just about every local Section meeting.

PRACTITIONERPROFILEJoshua Jones


At the national level, you’re currently a member of theGPR Ad Hoc Committee, correct?

Yes, and the GPR body of knowledge sub-committee.

What is the purpose of those committees?

We’re developing a body of knowledge in the hopes thatGPR will become a recognized testing method in its ownright. In that event, it will be required for GPR techniciansto become certified. Essentially, at this time, an individualcan buy the equipment from the manufacturer, takemanufacturer training and then go out and perform GPRtesting. There’s no standardized program or certification inplace to document levels of skill or training.

What publications are being considered for the body ofknowledge?

Right now, GPR publications don’t really exist. So, we’restarting from scratch and using established methods asmodels. Our first step has been to decipher informationprovided by all the different manufacturers of GPRequipment so that we can build new documentationapplicable to NDT. The information provided has beenpretty broad because the technology and equipment are

capable of doing so much. Much of it is focused forgeophysical applications like soil sampling or water flowunder asphalt. We are trying to consolidate everythingwe’ve learned and focus it at first for concrete.

You enjoy committee involvement.

I do. And I want to take it as far as I can. I’ll take on justabout anything they will throw at me.

If someone considering an NDT career asked for advice,what would you tell him or her?

It’s fun and a constant learning experience. It’s not difficult— not really hard work and there’s a lot to keep a personinterested. A lot of people don’t know that NDT exists. Theproblem is just getting people to get their foot in the door.

What are the growth areas of NDT — methods, industries?

Well, the NDT industry needs technicians in all methods.But, if you’ve got a person that’s technically oriented, UT isthe way to go. UT technicians are always needed. RTtechnicians are too. RT is sometimes dirty and can bedangerous if procedures aren’t followed carefully but RTtechnicians are always needed. TNT

Q: What is a “Body of Knowledge” and how does it relate to NDT?

A: The term “Body of Knowledge” (BoK) describes the knowledgefor a given area of expertise, and is also used to describe therepository that documents that knowledge. In the case of NDT,the most commonly recognized documents are those that listthe knowledge requirements required to achieve a certain levelof qualification. The BoK used by ASNT is the standardANSI/ASNT CP-105: Topical Outlines for Qualification ofNondestructive Testing Personnel.

Q: Please clarify the difference between “standard practice,”“standard guide” and “standard test method” in ASTMspecifications. S.P. Tamil Nadu, India

A: Definitions of terms are usually given in the foreword of thevarious volumes of the Annual Book of ASTM Standards. Thefollowing definitions with discussion can be also found in theASTM publication Form and Style for ASTM Standards.*guide: Compendium of information or series of options thatdoes not recommend a specific course of action. Increasesawareness of information and approaches in a given subjectarea.practice: Definitive set of instructions for performing one ormore specific operations or functions that does not produce atest result. Examples of practices include, but are not limited toapplication, assessment, cleaning, collection, decontamination,

inspection, installation, preparation, sampling, screening andtraining.test method: Definitive procedure that produces a test result.Examples of test methods include, but are not limited toidentification, measurement, and evaluation of one or morequalities, characteristics or properties. A precision and biasstatement shall be reported at the end of a test method (seeForm and Style for ASTM Standards, Section A21).

Q: I have read the “Focus” article in the January issue of TNT andwould like clarification on the stop bath emulsifier content. Amakeup of 0.25% emulsifier content for the test comparison ismentioned. What emulsifier should be used? Should it be afresh emulsifier or should it be from the emulsifier bath in use?When will the results of the CNDE fluorescent penetrantinspection research become part of the AMS 2647** standard?Z.H., Selangor, Malaysia

A: The comparison sample should be made up from a freshemulsifier. The concentration is based on experience at a majorairline, one of the CNDE company participants in the generationof the best practice document. The next version of AMS 2647 isexpected to be submitted for ballot in the summer of 2007.L.J.H. Brasche, ISU, Ames, Iowa

* Download a pdf of ASTM’s Form and Style for ASTM Standardsat <http://www.astm.org/COMMIT/Blue_Book.pdf>.

** SAE AMS 2647, Fluorescent Penetrant Inspection Aircraft andEngine Component Maintenance. Warrendale, PA: SAEInternational (October, 1999).

E-mail, fax or phone questions for the Inbox to the Editor:<[email protected]>, phone (800) 222-2768 X206,fax (614) 274-6899 X206, fax (614) 274-6899. TNT

INBOX•••••••••••••••••••••••••••••••••••••••••••



MaterialsandProcesses –Part I

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Across1. Attacks on metals by direct chemical action result in this.5. Test that uses a pendulum to break a notched specimen to

measure energy absorption.9. Decreases hardness, increases ductility and relieves stress.

10. Cast steel has more of these properties than wrought steel.12. The direct ________ test provides a measure of a materials’s

ability to resist surface penetration.16. Normalizing has the effect of increasing this property.17. Body-centered cubic is this type of structure.21. Test to determine ultimate strength of a material.22. Two approximate equilibrium heat-treatment processes are

annealing and ___________.23. Permanent deformation and ________ are two types of material

failure.24. If an inspection produced a 90% probability of detection (POD)

with a 95% __________ level, there is a 5% probability that thePOD is overstated.

26. NDT can determine the number and _____ of discontinuitiesthat exist in a material.

27 Eddy current can measure changes in electrical _____________caused by the effects of heat treatment.

30. Material __________, as used in design are generally determinedby material testing.

31. Undesirable by-product of steel-making process.32. Reduces brittleness.33. Type of furnace that typically produces highest quality steel.

Down2. Added to molten metal, this speeds up steel-making process.3. Kind of hardening that is also referred to as age hardening.4. Under ordinary usage, metals exist as this type of solid.5. Cast iron is usually considered when the application only

requires high ___________ strength.6. Steel having 40 ______ of carbon contains 0.4% carbon.

7. The reduction of iron ore by mixing with coke, limestone andoxygen is done in this furnace.

8. Process of returning ductility to cold worked low carbon steel.11. High carbon, low ductility iron produced in a blast furnace and

used to make subsequent types of iron and steel.13. Using NDT to find surface discontinuities that might result in

______ risers could prevent fatigue failure.14. ___________ materials (solid and plastic) would have reasonable

strength at room temperature.15. A good ________ control procedure ensures that unexpected

discontinuities of a critical size are not present when acomponent enters service.

18. Properties most important when corrosion resistance isessential.

19. If established criteria are exceeded, discontinuities canpropagate and become _______.

20. Work hardening is an increase in strength caused by plasticflow beyond this limit.

25. Stainless steels are corrosion-resistant and contain highpercentages of chromium and this element.

28. Iron can exist in several crystalline structures and its propertiescan be controlled by ____ treatment.

29. Young’s modulus of elasticity measures a material’s relativestiffness or _____ strength.

Across1.corrosion5.charpy9.annealing

10.isotropic12.hardness16.ductility17.lattice21.tensile

22.normalizing23.fracture24.confidence26.type27.conductivity30.properties31.slag32.tempering33.electric

Down2.oxygen3.precipitation4.crystalline5.compressive6.points7.blast8.recrystallization

11.pig

13.stress14.engineering15.fracture18.chemical19.defects20.elastic25.nickel28.heat29.yield

Answers

Clues for “Crossword Challenge: Materials and Processes” adapted from theASNT Level III Study Guide – Basic. Section III, Chapters 1-5.

Volume 6, Number 3 July 2007

Publisher: Wayne HollidayPublications Manager: Tim Jones

Editor: Hollis HumphriesTechnical Editor: Ricky L. Morgan

Review Board: William W. Briody, Bruce G. Crouse,Ed E. Edgerton, Anthony J. Gatti Sr., Jesse M. Granillo,Edward E. Hall, Richard A. Harrison, James W. Houf,Jocelyn Langlois, Eddy Messmer, Raymond G. Morasse,Ronald T. Nisbet, Angela Swedlund

The NDT Technician: A QuarterlyPublication for the NDT Practitioner(ISSN 1537-5919) is publishedquarterly by the American Society forNondestructive Testing, Inc. The TNTmission is to provide informationvaluable to NDT practitioners and aplatform for discussion of issuesrelevant to their profession. ASNT exists to create a safer world by promoting the professionand technologies of nondestructive testing.

Copyright © 2006 by the American Society for Nondestructive Testing, Inc.ASNT is not responsible for the authenticity or accuracy of informationherein. Published opinions and statements do not necessarily reflect theopinion of ASNT. Products or services that are advertised or mentioned donot carry the endorsement or recommendation of ASNT.

IRRSP, Materials Evaluation, NDT Handbook, Nondestructive TestingHandbook, The NDT Technician and www.asnt.org are trademarks of TheAmerican Society for Nondestructive Testing, Inc. ACCP, ASNT, Level III StudyGuide, Research in Nondestructive Evaluation and RNDE are registeredtrademarks of the American Society for Nondestructive Testing, Inc.

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