Image guide

NDT Images

AN OVERVIEW

Your guide to proper processing and interpretation ofradiography films for

Non-Destructive Testing (NDT)

INTRODUCTION

This guide addresses common artifactsthat result from poor film handling andshows how you can avoid them.

The guide is designed to help you identifyand understand a wide variety of castingand welding defects that appear on imagesobtained during Non-Destructive Testing(NDT).

FILM HANDLING ARTIFACTSWhile many factors can affect imagequality, macroscopic defects known asartifacts are sometimes produced duringfilm handling and processing. Theseartifacts degrade film images. If imagesare seriously degraded, interpretationsand analyses derived from those imageswill be compromised. Often, thoseanalyses will be completely unsatisfactory.

To make sure you achieve the highestquality images — and operate cost-effectively — it is critical to minimize thenumber and types of artifacts that appearon processed films. The solution is simple.Proper film handling practices willprevent nearly all artifacts thatcompromise NDT films.

Section I of this guide defines the mostcommon film handling artifacts anddescribes what causes them. Detailedtroubleshooting procedures are offered tohelp you prevent similar artifacts fromforming in the future.

Section II offers general procedures youcan follow to prevent the formation ofartifacts.

WELD AND CASTING DEFECTSIt’s critical that your NDT programsproduce the best possible data. This guidewill help you identify the wide variety ofartifacts and NDT defects, from crimps tostreaks, from micro-fissures to gas voids.

Section III addresses defects typicallyfound in images of Castings.

Section IV helps identify defects found inimages of Welds.

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TABLE OF CONTENTS

Sections Page Film Handling Artifact

Introduction 1

Section I 5 Pressure MarksFilm Handling 7 Crimp MarksArtifacts (after exposure)

9 Crimp Marks(before exposure)

11 Static Marks13 Poor Definition15 Spots (fixer)17 Spots (developer)19 Hair Lines21 Screen Marks23 Paper Marks25 Black Streaks or

Blotches27 Streaking29 Pressure Marks

(from automatic processing)31 Pi Lines

(from automatic processing)33 Random Black Spots

(from automatic processing)

Section II 34-35 Film handling practicesGeneral Film in processing Processing & environmentsHandling 36-37 Darkroom conditions: Guidelines practice and

maintenance38-39 Film processing

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TABLE OF CONTENTS

Sections Page Defect

Section III 41 ShrinkageDefects in 43 Gas VoidsCastings 45 Inclusions

47 Unfused Chaplet49 Hot Tear51 Cracks53 Core Shift

Section IV 55 Cluster PorosityDefects in 57 Excess PenetrationWelds 59 External Undercut

61 Internal (Root) Undercut63 Lack of Penetration65 Tungsten Inclusions67 Slag Lines69 Lack of Fusion71 Scattered Porosity73 Mismatch75 Elongated Slag Inclusions

or “Wagon Tracks”77 Weld Spatter79 Longitudinal Cracks81 Transverse Cracks83 Burn Through

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I

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PRESSURE MARKS

WHAT DO THEY LOOK LIKE?

A pressure mark exhibits a significantlylower density compared to adjacent areas.

WHAT CAUSES THEM?

A severe localized application of pressureto an area of the film before exposure.

WHEN CAN THESE OCCUR?

The major cause of pressure marks is poorfilm handling during the preparation ofcassettes. Film may be pinched in thecassette at some point in the handlingprocess. An object dropped on thecassette can also cause pressure marks.

HOW DO I TEST FOR PRESSURE MARKS?

Carefully prepare another cassette of filmdirectly from the same box. Expose andprocess the film. If you don’t see defectslike you saw the first time, what you sawthe first time is likely a pressure mark.

HOW CAN I PREVENT THEM?

Always handle film with care. Avoid anytype of pressure on the film.

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CRIMP MARKS (AFTER EXPOSURE)


Crimp marks appear as crescent-shapeddefects that are darker (higher density)than adjacent film areas.

WHAT CAUSES THEM?

Any sharp bending of the film afterexposure and just before or duringprocessing will crimp the film.


This usually happens when film is handledimproperly when cassettes or hangers arebeing unloaded.

HOW DO I TEST FOR POST-EXPOSURECRIMP MARKS?

Expose some film and then intentionallycrimp or kink it. Process the film andexamine the film with reflected light.Chances are you’ll see one or morecrescent-shaped defects.


Handle the film with care. To carry a singlesheet, gently bend the film in half and holdit in a “3-point grip”, that is, grasp it withyour thumb and middle finger and placeyour index finger in between to keep thefilm surfaces separated. It’s easier if youkeep the long dimension parallel to thefloor.

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I

CRIMP MARKS (BEFOREEXPOSURE)


Crimp marks appear as crescent-shapeddefects that are lighter (lower density)than adjacent film areas.

WHAT CAUSES THEM?

Sharp, abrupt bending of the film beforeexposure causes crimp marks of this type.


This usually happens when film is handledpoorly when removing a sheet from a boxor loading a cassette prior to exposure.

HOW DO I TEST FOR PRE-EXPOSURECRIMP MARKS?

Intentionally crimp or kink some film,expose it, then process normally. Examinethe film and you’ll probably see lightercrimp marks where you mishandled thefilm.


Handle the film with care. To carry a singlesheet, gently bend the film in half and holdit in a “3-point grip”, that is, grasp it withyour thumb and middle finger and placeyour index finger in between to keep thefilm surfaces separated. It’s easier if youkeep the long dimension parallel to thefloor.

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I

STATIC MARKS


Static marks appear as either jagged,branching dark lines or irregular andintense dark spots. Static marks are similarto certain casting irregularities.

WHAT CAUSES THEM?

The dissipation of static electricity causesstatic marks.


Removing film quickly from its box whenthe relative humidity is low (a bad hairday) is the most common cause of staticmarks.

HOW DO I TEST FOR STATIC MARKS?

Shuffle your feet or rub your hair beforehandling film. Sometimes you’ll see or hearthe static discharge. After processing, ifyou see jagged lines or dark spots, chancesare good you’ve got static marks.


Keep film at a relative humidity that’sgreater than 40%. Avoid sliding the filmsor moving fast when removing film from itsbox.

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POOR DEFINITION

WHAT DOES IT LOOK LIKE?

Poor definition is simply a term to describeimages that are not sharp.

WHAT CAUSES IT?

In most cases, poor definition is caused bya lack of contact between the screen andthe film.

WHEN CAN THIS OCCUR?

Any time there’s not enough, or poor,contact between lead or fluorescentscreens and the film you can get “unsharp”images.

HOW CAN I PREVENT IT?

Simple. Just make sure your screen andfilm path are adjusted to correct tolerancesand properly aligned.

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SPOTS (FIXER)


Spots from fixer will appear as small spotsof a lower density than the surroundingfilm area.

WHAT CAUSES THEM?

Before development, a splash of fixer, evenin trace amounts, will cause spots.


Any time there’s chemical contaminationyou can have a problem. In this case, it’susually due to a poor darkroom layout orcareless processing techniques.


Don’t splash fixer, of course. And ingeneral, keep film loading areas completelydry.

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SPOTS (DEVELOPER)


Spots from developer will appear as smallspots of a high density compared to thesurrounding area of the film.

WHAT CAUSES THEM?

A touch or splash of developer prior todeveloping the film will cause this type ofspot.


Poor processing techniques or a baddarkroom layout can lead to spots.


Don’t splash chemicals of any kind. Makesure your film loading area is totally dry.

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HAIR LINES


Hair lines look like just what they are — avery slender white line across a filmnegative. They can also be spots createdby lint or dust.

WHAT CAUSES THEM?

In most cases, a hair between the film andthe screen causes a line. Lint or dust willcause irregular spots or shadow images.


Contamination can occur anywhere in theprocess of handling films and screens.

HOW DO I CHECK FOR HAIR LINES?

Closely and carefully inspect cassettes andscreens.


Keep all your work areas clean, and asclose to spotless as possible.

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SCREEN MARKS


A screen mark will appear as a dark line ona negative. Screen marks will also appearas white spots on a negative.

WHAT CAUSES THEM?

A dark line is caused by a deep scratch onthe lead foil screen. Light spots are causedby flakes of foreign material on the screen.


You’ll see screen marks when a screen isscratched or damaged in some way.They’re also produced when foreignmaterials get into your equipment.

HOW DO I CHECK FOR SCREEN MARKS?

Inspect your screens closely. If you seedamage of any kind, they must bereplaced. If you’re not sure, replace thesuspect screen with a new one and runsome film tests.


You should avoid scratching screens, ofcourse, and always maintain meticulouslyclean work areas. In addition, use lead-pack film formats when possible.

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PAPER MARKS


A paper mark will appear as a low densityarea that almost completely covers thefilm.

WHAT CAUSES THEM?

Paper marks appear when the paper getson the film and screen and casts a shadowof itself.


This happens when the interleaving paperis not removed.

HOW DO I CHECK FOR PAPER MARKS?

It’s easy. Just run test exposures with andwithout the interleaving paper.


Make sure you completely remove theinterleaving paper before making anexposure.

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I

BLACK STREAKS OR BLOTCHES


They look just like their name: blackstreaks or blotches.

WHAT CAUSES THEM?

Extraneous light creates black streaks orblotches.


Most often these defects happen whenlight leaks in because a cassette or filmholder is damaged or faulty.

HOW DO I TEST FORSTREAKS/BLOTCHES?

Remove a sample piece of film in totaldarkness, ensuring there’s no chance itcould have been exposed by light. Processthe film and examine it.


There are a number of steps you shouldtake. Check and properly maintain yourcassettes. Secure them with tape or rubberbands as necessary. And finally, make sureyour safelights are really safe.

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STREAKING


Streaking is defined as a line, smear, orband. In this case it can be black or white.

WHAT CAUSES IT?

Streaks are caused by any of several typesof chemical contamination. Thecontamination often occurs in poordarkroom setups or because of improperprocessing technique.

WHEN CAN IT OCCUR?

Streaks of this type happen whenchemicals from prior processing cycles arenot completely removed from hangers.

HOW CAN I PREVENT IT?

Avoid overcrowding hangers. Make sureyou rinse equipment carefully andcompletely. Also keep film loading areasdry and free of chemical splashes.

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I

PRESSURE MARKS(FROM AUTOMATIC PROCESSING)


Pressure marks appear as dark lines ordark spots.

WHAT CAUSES THEM?

A buildup of chemical deposits inautomatic processing or mechanicalpressure on the film can create pressuremarks.


Poor processor maintenance is the primarycause. This includes both foreign matter onrollers and incorrect roller clearances.


Thoroughly clean automatic processorrollers on a regular basis and make surethey are mechanically maintained and upto spec.

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PI LINES (FROM AUTOMATICPROCESSING)


A Pi (π) line is a very specific artifact: adark line at a distance from the leadingedge of the film that’s exactly equal to thecircumference of the roller in yourautomatic processor.

WHAT CAUSES THEM?

Pi lines are caused when minute chemicaldeposits are transferred from the roller tothe film.


They are often spaced in a regularsequence, separated by the circumferenceof the roller.

HOW DO I TEST FOR PI LINES?

Measure the exact distance between thelines. If the artifact is repeated again andagain at the same spacing with diminishingdensity or intensity, and the distancebetween the lines is equal to thecircumference of the roller, you have Pilines.


Make sure the rollers in your automaticprocessors are carefully and completelycleaned and rinsed on a regular basis.

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I

RANDOM BLACK SPOTS (FROMAUTOMATIC PROCESSING)


Random black spots look like black cometswith their tails extending in the directionof the film travel.

WHAT CAUSES THEM?

Chemical contamination causes randomblack spots.


Either the processor or some of itscomponents are contaminated, or foreignparticles have fallen on the film as itenters the processor.


Clean your automatic processor, carefullypaying special attention to the feed traysand entrance rollers.

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FILM HANDLING PRACTICES IN PROCESSING ENVIRONMENTS

Your images must be accurate and offerthe highest quality. They must providecool, clean image tones, low noise, highcontrast and excellent definition. An imagethat’s flawed is useless. A test that has tobe repeated wastes time and resourcesand costs you money. Your productivitysuffers.

In each category, defects can be drasticallyreduced with proper care and considera-tion. Ensure that you:

• Properly set-up your facility.

• Keep your darkrooms clean.

• Handle and process film using propermethods.

• Keep equipment and workspaces clean.

• Rigorously maintain film processingequipment.

• Be gentle.

To minimize the possibility of creatingartifacts, make sure your darkrooms andfilm loading rooms are clean. Maintain filmprocessors regularly, and always handlefilms with tender loving care and commonsense.

Artifacts can be virtually eliminated byfollowing these guidelines.

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II

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FILM HANDLING

• Be careful of metal surfaces.

• Handle film only by its edges.

• Use the fingertips of both hands.

• To carry a single sheet, fold film in halfand hold it in a “3-point grip” betweenthumb and middle finger, with indexfinger in the center to keep film surfacesseparated.

• Give yourself room to spread out.

• Carry film flat in trays or boxes.

• Wear gloves.

• Avoid jewelry that may have sharp edges.

• Clean film as recommended– Wipe in one direction, not in a circular

motion.– Use Clean Room Wipes,

Environmentally Safe Film Cleaners,TEKNEK Rollers or equivalent tackyroller cleaners.

IN THE PHOTO LAB

• Be careful removing raw film from theoriginal package to avoid scratching andstatic.

• Load cassettes with care.

• Minimize exposure to dirt and dust whenhandling and transporting film.

• Carefully package and deliver film to theevaluators or technicians.

DARKROOM CONDITIONS: PRACTICE AND MAINTENANCE

Darkroom practices may be consideredunder several categories:

MATERIALS

• Avoid shedding materials such as paper,or cardboard boxes by using intermediatecontainers (such as plastic containers) totransport materials to the darkroom.

• Avoid large storage areas near thedarkroom by practicing Just-In-Timedelivery.

EQUIPMENT

• Should not generate contaminants (suchas rust).

• Should not interfere with filtered air flowand/or cause turbulence.

• Surfaces should be easy to clean. (i.e.,smooth, glossy, no crevices)

• Perform maintenance outside the darkenvironment when possible.

• Stainless steel tables and wire coatedracks are good choices for use indarkrooms.

PHYSICAL LAYOUT

• Locate equipment to optimize processflow.

• Steps of the workflow should physicallyfollow each other and not traverse backand across the work area.

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TRAINING

• Operators should understand whydarkroom cleanliness is necessary andhow they can contribute to keeping itclean.

• Encourage people to spot problems andprovide solutions to maintain a cleandarkroom.

FACILITY

• Inspect all surfaces of the facility andequipment; tables, chairs, etc.

• Inspect and remove rust, corrosion, andflaking paint.

• Repaint with epoxy paint wherenecessary or use high-gloss paint foreasy cleaning.

• Use hard surface materials for flooring,never carpet.

• Use laminate coated ceiling tiles.

• Lighting must meet needs of the process and product. You should follow the manufacturers’ safelightrecommendations.

• Delivery systems and conduits should bemade of non-shedding inert material.

CLEANING

• Schedule cleaning so it does not interferewith production.

• Cleaning should proceed from highestsurface level to lowest, and from cleanestareas to less clean.

• Cleaning should be followed by a periodof time to allow dust to settle; do thisbefore restarting production.

FILM PROCESSING

Make sure you are processing film at therecommended development time andtemperature. Kodak recommended timesand temperatures can be found in theTechnical Datasheets on our websites forall KODAK Films. Underdeveloping willcause low D-max and affect image quality.Make sure processor guides and rollers areproperly aligned and crossovers adjustedcorrectly. Clean tanks of bioslime andmaintain the processor to avoid:

• Dirty entrance rollers.

• Dirty top rollers.

• Salt crystals on crossover guides.

• Dirty squeegee rollers at entrance todryer.

• Particulates on dryer rollers.

PREVENTATIVE MAINTENANCEPRACTICE:Developer and Use 10 µm filter.Fixer Filtration Change weekly.

Water Filtration 25 µm or smaller filter is best.Change weekly.

Daily Clean all top rollers, entranceMaintenance rollers, crossovers, wash to

dryer squeegee rollers.

Weekly Remove all racks, developer,Maintenance fixer,and clean with high-

pressure hot water. Use brushesto clean. Avoid scratchingstainless steel withSCOTCHBRITE Pads orequivalent.

KODAK Roller Use daily to remove particles. Transport Especially important to use Cleanup Film immediately after cleaning 4955 racks and after system

cleanings.

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PROCESSOR MAINTENANCE:

Controlling bioslime growth

• Minimize bioslime, a major cause ofpinhole emulsion pick off.

• Daily addition of 30 mL (1-oz) ofhousehold bleach will help to dissolvegelatin particles, preventing redepositsand minimizing bioslime growth.

• WASHCLEAR, from Rothtech Ecological,has also proven to be very effective.

• Proxel GLX from Avecia, Inc. is alsoeffective with a convenient auto-feeddispenser to the processor.

• Drain wash tanks when not in use orwhen shutting down your processor.

CLEANING FILM

To clean film, use only isopropyl alcohol(91 percent) or heptane. Soft, lintless,absorbent cotton pads, Webril Handi-Pads,or their equivalent should be used. Neveruse water because it will soften the gelatin.

• Apply cleaner to the cleaning wipe.

• Wipe film in a single up-and-downdirection, NOT in a circular motion.

• Fold the cleaning wipe frequently to keepdirt particles away from the film surface.

• Change wipes often.

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SHRINKAGE


Shrinkage is indicated when you seeseveral minor areas of differing densitybranching away from a major, abrupt lineardefect. Shrinkage looks a lot like a tree witha thick trunk and several branches.

WHAT CAUSES SHRINKAGE?

When adjacent thick and thin portions of acasting cool unevenly, and the portionsshrink at varying rates, a discontinuitybecomes evident.

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III

GAS VOIDS


A gas void appears as a smooth dark spot.It can be round, oval, or elongated. Thesizes of these spots can vary considerably.

WHAT CAUSES GAS VOIDS?

When gas is trapped in a casting, itnaturally produces a void. The gas canerupt spontaneously from molten metal,and it can develop from water vapor orgreen sand in a mold. In addition, duringthe pouring of a mold, gas voids can formas a result of simple turbulence.

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III

INCLUSIONS


Inclusions usually exhibit lower densitythan gas voids. They’re more diffuse thangas voids and irregular in shape, that is,not oval or spherical.

WHAT CAUSES INCLUSION?

Inclusions develop when low-densityforeign matter and/or sand are entrappedin the molten metal and don’t dissolve.

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III

UNFUSED CHAPLETS


An unfused chaplet is the dark outline of ashape similar to the shape of the chapletitself.

WHAT CAUSES UNFUSED CHAPLETS?

Chaplets are used to maintain cores intheir correct position during the castingprocess. When a chaplet is not fusedcompletely by the molten metal, adiscontinuity is formed.

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III

HOT TEAR


A hot tear is a dark, jagged, linearindication. It may be intermittent.

WHAT CAUSES THEM?

Excessive thermal stress in cooling metalmay produce this tearing or rendering.

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III

CRACKS


Cracks in castings appear as dark linearindications. They may be either feathery orjagged.

WHAT CAUSES CRACKS?

Cracks are caused when metal fracturesduring or after solidification.

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III

CORE SHIFT


A core shift is just what it sounds like. Theshift of the core is easily seen because thecored-out section is always darker than themetal.

WHAT CAUSES IT?

Sometimes, as molten metal is beingpoured, the core material shifts.

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IV

CLUSTER POROSITY


Cluster porosity will appear as rounded orslightly elongated dark spots that appear inclusters.

WHAT CAUSES IT?

Clusters of trapped gas cause clusterporosity.

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IV

EXCESS PENETRATION


Excess penetration appears as a lighterdensity area in the center of a weld image.This area can be extended along the weldor isolated in circular drops.

WHAT CAUSES IT?

These indicators can appear when there isexcess metal at the root of the weld.

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IV

EXTERNAL UNDERCUT


External undercut appears as an irregulardark density line that follows the edge ofthe weld image.

WHAT CAUSES EXTERNAL UNDERCUTS?

These appear when there’s a groove orchannel in the surface of the plate alongthe edge of the weld.

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IV

INTERNAL (ROOT) UNDERCUT


Internal (root) undercut appears as anirregular dark density near the center ofthe weld image and along the edge of theroot pass image.

WHAT CAUSES IT?

An internal undercut is caused by a groovein the main object stretched along theedge, either at the bottom or at the innersurface of the weld.

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IV

LACK OF PENETRATION


Lack of penetration will appear as darklines, either continuous or intermittent, inthe center of the weld.

WHAT CAUSES IT?

There are two causes: either a lack offusion in the root of the weld, or a gap leftby the failure of the weld metal to fill theroot.

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IV

TUNGSTEN INCLUSIONS

WHAT DOES DO THEY LOOK LIKE?

Tungsten inclusions appear as randomspots in the weld image that exhibitirregular lower densities.

WHAT CAUSES THEM?

They’re caused when small pieces oftungsten become trapped during thewelding process.

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IV

SLAG LINES

WHAT DOES DO THEY LOOK LIKE?

Slag lines are darker density lines that areirregular in width running parallel to theedge of the weld.

WHAT CAUSES THEM?

Elongated cavities that contain slag orother low-density foreign matter willproduce slag lines.

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IV

LACK OF FUSION


Lack of fusion appears as an elongatedsingle, or several parallel, darker densitylines. Unlike winding and elongated slaglines, lack of fusion lines are very straightand aligned lengthwise. Sometimes darkerdensity spots are dispersed along the lackof fusion lines.

WHAT CAUSES IT?

Lack of fusion is the result of elongatedvoids between the weld metal and basemetal.

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IV

SCATTERED POROSITY

WHAT DOES DOES IT LOOK LIKE?

Scattered porosity appears as a dark andsharply-defined shadow with roundedcontours.

WHAT CAUSES IT?

Gas trapped in cavities produces scatteredporosity.

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IV

MISMATCH

WHAT DOES DOES IT LOOK LIKE?

A mismatch is an abrupt change in filmdensity across the entire width of the weldimage.

WHAT CAUSES A MISMATCH?

Mismatches occur when plates are notaligned properly before welding.

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IV

ELONGATED SLAG INCLUSIONS OR “WAGON TRACKS”


Elongated slag inclusions or “wagontracks” are darker density lines — either asingle line or several in parallel — that areirregular in width.

WHAT CAUSES ELONGATED SLAGINCLUSIONS OR “WAGON TRACKS”?

These are caused when elongated cavitiesdevelop on both sides of the root, and thecavities contain slag or other foreignmatter.

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IV

WELD SPATTER


Weld spatter appears as white spots nearthe weld.

WHAT CAUSES THESE SPOTS?

These spots are caused by the metalparticles expelled during fusion weldingthat do not form a part of the weld.

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IV

LONGITUDINAL CRACKS


Longitudinal cracks are dark lines, eithercontinuous or intermittent, along thelength of a weld.

WHAT CAUSES THEM?

These cracks are discontinuities caused byfractures along the length of a weld.

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IV

TRANSVERSE CRACKS


A transverse crack is a fine dark linerunning across a weld image. These linescan be straight or wandering.

WHAT CAUSES THEM?

These cracks are caused by metal fracturesthat occur across a weld.

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IV

BURN THROUGH


A burn through is a localized darkerdensity area with fuzzy edges right in the center of the weld image.

WHAT CAUSES IT?

These are caused by a severe depressionor a crater-type hole at the bottom of theweld.

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For more than a century, Kodak has been apioneer in imaging and a leader in quality.Our goal has always been to make thecapture, distribution and display of imageseasier, faster, more useful and costefficient. Whenever imaging is your focus,Kodak is there to help you get the jobdone.

For more information on KODAKINDUSTREX Products for Non-Destructive Testing, contact yourlocal Kodak sales representative or visitwww.kodak.com/go/ndtproducts today.

Or contact us at:

Eastman Kodak CompanyNDT Products343 State StreetRochester, NY 14650-0505e-mail: [email protected]/go/ndtproducts

Eastman Kodak CompanyRochester, NY 14650 USA

© Eastman Kodak Company, 2003. Kodak and Industrex are trademarks. IMC-949 CAT No. 892-4177

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