AD-AO96 j3 CIVIL ENGINEERING LAB (NAVY; PORT HUENEME CA F/ G11/A

NONDESTRUCTIVE TEST EQUIPMENT FOR WIRE ROPE. U)N

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title: NONDESTRUCTIVE TEST EQUIPMENT FOR WIRE ROPE.

DTICI,.:' ELECTE".

author: H. H. Haynes C L. D./Underbake - Thdate: oct 98.1 e , / _ 111P E

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sponsor: Naval Facilities Engineering Commandj'

program nos: Y0995-01-004 621

I"L CIVIL ENGINEERING LABORATORYNAVAL CONSTRUCTION BATTALION CENTER

Port Hueneme, California 93043

Approved for public release; distribution unlimited.

81 3 26 007

UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE (Who,, oes Fn,.,rd)

PAGE READ INbTRUCT[ONSREPORT DOCUMENTATION PAEBEFORE COMPLETING FORM

1, REPORT NUMBER ZGO) CESS ON NO. 3. RECIPIENT'S CATALOG NUMBER

4. TITLE (And Subtitle) 5 TYPE OF REPORT & PERIOD COV]ERED

NONDESTRUCTIVE TEST EQUIPMENT Not final; Sep 1979 - Sep 1980FOR WIRE ROPE '6 PERFORMING ORG. REPORT NUMBER

7. AUTHOR(.) S. CONTRACT OR GRANT NUMBER(.)

It. If. Haynes and L. D. Underbakke

B PERFIORMI NG ORGANIZATION NAME AND ADDRESS 10 PROGRAM ELEMENT. PROJECT. TASK

CIVIL ENINEERING LABORATORY AREA A WORK UNIT NUMBERS

Naval Construction Battalion Center 63725N;Port Hueneme, California 93043 Y0995-01-004-621

11I. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE

Naval Facilities Engineering Command October 1980

Alexandria, Virginia 22332 13, NUMBER OF PAGES________________ 32

7r MONITORING AGENCY NAME A ADORESS(II dell-r-t I-o~ C,,rIing Off-~) IS. SECURITY CLASS. (of this0 report)

UnclassifiedIS.. DECLASSIFICATION'DOWNGRADING

SCHEDULE

IA DISTRIPUTION STATEMENT (of the. Report)

Approved for public release; distribution unlimited.

I7 DISTRIBUTION STATEMENT (of Ihe abstract reIored In Blo.ck 20, it dIll.,.,,, from, Report)

IS SUPPLEMENTARY NOTES

IN KEY WORDS (C-11..n,. a,,,I.id. it o .... yy reed id,,nify by block, .- ~bar)

Wire rope, steel cable, inspection, nondestructive test, nondestructive evaluation, electro-

magnetism, flall effect sensors.

20 ABSTRACT (Cortiriefl ,...... . id. It necessary .,d Id,-IIy by, block -m~bor)

Nondestructive test equipment for inspecting steel wire ropes was evaluated in labora-

tory and field tests. Individual AC/DC units and a unitized AC/DC unit were tested on wirerope to detect broken wires and loss of ,ietallic area from wear and corrosion. The unitized

AC/DC units used Hall effect sensors to pick up the defects as opposed to sensor coils used4

in the individual AC/DC units. The I all effect sensors enabled less equipment to be used to

conduct a complete inspection and also permitted the wire rope to be inspected at speeds(coninued

DO , 1473 EDITION OF I NOV N5 IS OBSOLETE UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE (Wh, eep FnI.,edl

UnclassifiedSECURITY CLASSIFICATION O

F THIS PAGE(Wbhn 0.I. E.nI.,d)

20. Continued

from 0 - 500 fpm. It is recommended that Navy facilities requiring nondestructive testinspection capability for metallic wire rope inspection procure the unitized AC/DC unit.

Civil Engineering LaboratoryNONDESTRUCTIVE TEST EQUIPMENT FOR WIRE ROPE,by H. H. Haynes and L D. UnderbakkeTN-1594 32 pp illus October 1980 Unclassified

1. Wire rope 2. Nondestructive testing 1. Y0995-O1-004-621

Nondestructive test equipment for inspecting steel wire rope was evaluated in labora-

tory and field tests. Individual AC/DC units and a unitized AC/DC unit were tested on wire

rope to detect broken wires and loss of metallic area from wear and corrosion. The unitized

AC/DC units used Hall effect sensors to pick up the defects as opposed to sensor coils used

in the individual AC/DC units. The Hall effect sensors enabled less equipment to be used

to conduct a complete inspection and also permitted the wire rope to be inspected at speeds

from 0 - 500 fpm. It is recommended that Navy facilities requiring nondestructive test

inspection capability for metallic wire rope inspection procure the unitized AC/DC unit.

UnclassifiedSECURITY CLASSIFICATION OF THIS PAG5fWh.n Doe. Fn,..d

I l il iIi -, i -I'

CONTENTS

Page

INTRODUCTION ............ ........................... 1

BACKGROUND .............. ............................ 2

THEORY ............... .............................. 3

Individual AC/DC Units .......... .................... 3

DC Unit ............ ......................... 3AC Unit ............ ......................... 4

Unitized AC/DC Unit .......... ..................... 4

TESTS ............... ............................... 5

Laboratory Test .......... ....................... 5Field Tests ............ ......................... 6

Manitowoc Crane .......... ..................... 6Floating Crane .......... ..................... 7

COMPARISON OF FEATURES ........... ...................... 8

SUMMARY ............... .............................. 8

RECOMMENDATIONS ............. .......................... 8

APPENDIX - Description of Noranda's Magnograph Equipment ..... ... 21

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INTRODUCTION

Wire rope inspection is a problem to the Navy. At present only theoutside surface of wire ropes can be inspected for broken wires, wear,and corrosion. Typically, an inspector uses a rag held around a movingwire rope as an aid in finding broken wires (Figure 1). Caliper measure-ments of the outside diameter of the wire rope give data on wear, andrust stains indicate corrosion. However, inspection cannot be completewithout knowledge of the condition of the interior of the rope. Therefore,wire rope replacement criteria are based on conservative standards,because the alternative is risk of injury or loss of life from a ropefailure.

Nondestructive test (NDT) devices have the capability to detectbroken wires, wear, and corrosion throughout the entire cross section ofa metallic wire rope. This inspection technique is an order of magnitudesuperior to the present visual method. Because the condition of therope is known with confidence, accidents could be reduced and replacementcriteria improved.

The Office of Safety and Health Administration (OSHA) requires thatwire ropes be inspected periodically (frequency of inspection depends onthe application.) The Department of Defense follows OSH{A guidelines,and many man-hours are used for wire rope inspections. Potential usersof NDT inspection equipment within the Department of Defense are numerous.The following applications are indicative of potential users:

- Crane wire ropes

- Personnel elevator wire ropes

- Ship cargo elevator wire ropes

- Bridge cables

- Mooring lines

- Underway replenishment cables for ships

- Catapults and arresting cables on aircraft carriers

- Undersea cable arrays

'I- Tether lines for diving bells

- Guy lines for transmission and receiving antenna towers

- Tramway wire ropes

To expand on one application, that of cranes, the Long Beach Naval

Shipyard has about 430 cranes, both large and small, that require inspec-tion. This shipyard is only one of eight Navy yards. The inspectorshave the authority to ''red tag' any wire rope that they deem unsafe and,thus, prevent the use of the crane until the rope is replaced. NDT

equipment would greatly help the inspector in making decisions on whethera wire rope is safe by supplying technical data on the condition of therope. Also, because some conservativism can be replaced by knowledge,it is likely that wire ropes will remain in service for longer periodsof time.

This report on evaluating nondestructive test equipment for wirerope was sponsored by the Naval Facilities Engineering Command under theSpecialized Inspection Systems (SPINS) Project.

BACKGROUND

NDT --:wuipment for inspection of wire rope has been used for over 25yr by the mining industry in many countries.* The United States has notparticipated in the mining industry's development of NDT inspectionequipment.

Two basic types Gf equipment have been developed, which will bejointly called "individual AC/DC units." The AC unit uses alternatingcurrent to produce an electromagnetic field to detect loss of metallicarea in the wire rope. The DC unit uses permanent magnets (analogous toa steady direct current) to detect broken wires. Typically, either ACor DC equipment is used in an inspection, seldom both. If DC is used,the wire rope needs to be demagnetized before AC can be used. Thedegaussing process is slow.

Recently a Canadian firm** developed a "unitized AC/DC system."This equipment can perform the functions of the individual AC/DC unitsduring one pass of the wire rope through a sensor head. The equipmentalso has the feature of inspecting wire rope traveling at speeds fromextremely slow to fast (0 - 500 fpm), whereas the individual DC unit canonly function at rope speeds ranging from 50 to 500 fpm. The slowspeeds are invaluable when trying to locate broken wires for detailedvisual inspection.

During 1979, the Civil Engineering Laboratory worked with an indi-vidual DC unit. A U.S. firm,-* * which manufactured NDT equipment forquality control inspection of small diameter pipe, was contracted by CELto adapt their equipment to 1-1/8-inch-diameter wire rope. The equipmentused the same engineering principles of operation as the individual DCunit for wire ropes. The equipment was tested, and the results werereported in Reference 1.* -*

*Partial list of manufacturers of NDT equipment for wire rope:

Kundig AG, SwitzerlandAcademy of Mining and Metallurgy, PolandRotesco Ltd., CanadaACMI, BelgiumMitsui Miike, JapanPlessey-Slack, South Africa

**Noranda Research Centre, Quebec, Canada. [Manufacturer is Heath and

Sherwood (1964) Limited, Ontario, Canada.]

***Magnetic Analysis Corporation, New York.

****Civil Engineering Laboratory. Technical Memorandum M-40-80-2-R:

Report on NDT inspection of wire rope using electromagnetic equipment,by Earl F. Buck, Phillip C. Zubiate, and Harvey H. Haynes. PortHueneme, Calif., Mar 1980.

2

During the same time period, Noranda began to market a unitizedAC/DC unit, called a ?agnograph. CEL observed a demonstration test andsubsequently procured a Magnograph unit for test and evaluation work.

During one sequence of laboratory and field tests, individual AC/DCunits were tested side-by-side with the Magnograph. The Mine Safety andHealth Administration, who owned and operated the individual AC/DC unitsfor about 1 year, came to CEL with its equipment and an experiencedoperator for the comparison tests. The results of the comparison arepresented herein along with other results and information on the Magnographunit.

THEORY

The principles of operation for the individual AC/DC units and theunitized AC/DC unit will be discussed in the following sections.

Individual AC/DC Units

DC Unit: In the DC unit, strong permanent magnets are placedaround a section of wire rope so that the rope becomes saturated withmagnetic lines of flux (Figure 2). Lines of flux can be observed byiron filings sprinkled on top of a piece of paper having magnets under-neath (Figure 3). The flux appears to "flow" from the north to southpole; however, the lines are stationary. The lines of flux are alsodistinct because of the existence of both attractive and repulsiveforces. Saturation means that if stronger magnets were used, the numberof lines of fiux for a given cross section (flux density) would remainessentially unchanged.

If a broken wire were present in a saturated section of rope, thena north and south pole would be formed and the lines of flux would"jump" the gap (Figure 4). It is these lines of flux, called fluxleakage, that can be detected to indicate a broken wire. Pitting fromcorrosion and localized wear will also interrupt the saturated lines offlux and cause flux leakage.

A classic physics experiment is to demonstrate that a magneticfield can produce an induced voltage in a conductor that is passedthrough the magnetic field. The conductor, passing at right anglesthrough the lines of flux, must have a minimum travel speed through theflux field in order for the voltage to be large enough to measure(Figure 5).

Flux leakage in the wire rope is detected by using this phenomenon.However, in this case, the conductor is a search coil that is heldstationary while the magnetic field is moving. In the inspection equip-ment, search coils are placed around the saturated wire rope between thepoles of the permanent magnet. The rope travels at some minimum speed;thus, any flux leakage will also be moving and will pass through thesearch coils (Figure 6). When this occurs, an induced voltage is gener-ated in the search coils, and, by proper amplification and conditioningof the signals, the broken wire is detected.

For the DC unit, there must be relative motion between the sensorcoil and the wire rope. This means that the rope must travel throughthe sensor head or, for a stationary rope, the sensor head must travelalong the wire rope. A minimum velocity of about 50 fpm is required.

3

Below this speed the induced voltage in the sensor coil is too small todetect broken wires. The velocity must also remain constant for signalstrength to be consistent; however, to account for changes in velocity,the DC unit is built with a tachometer coupled to an amplifier so thatsignal strength can be amplified for changes in velocity.

Two searc. coils are usually built into the sensor head, as shownin Figure 6, to allow the head to clamp around the rope. Data outputcan take several forms because signals from two search coils are avail-able. Usually two output traces are shown so signals from coil A anid Bcan be displayed as a combination of A, B, A + B, (A + B)2 or AB.Typically the data is displayed as A + B on one trace and (A + B)2 onthe second trace.

AC Unit: A relatively weak alternating magnetic field is producedby electromagnets in an AC unit sensor head. These magnets function asthe primary coil of a transformer (Figure 7). The wire rope serves thepurpose of the ferromagnetic core of a transformer. A secondary coil inthe middle of the sensor head produces an Output voltage that is propor-tional to the magnetic flux "flowing" through the wire rope. Variationsin the cross-sectional area of the wire rope influences the strength ofthe magnetic flux field and, thus, the strength of the output voltage.Hence, loss of metallic area can be measured by the output voltage.

The sensor coil measures the metallic volume over a 2- to 3-inchlength of wire rope. Wear and corrosion can produce a significantvolue change within the finite length, but a single broken wire with asmall gap between the ends reduces the volume insignificantly. If manybreaks occur within the finite length or a wire is missing, then adefect signal may be recorded.

In the AC unit, the magnetic flux field always varies with timebecause of the alternating field. Hence, a voltage is produced in thesensor Coil WhLaer or not the rope moves.

Because of the alternating magnetic field, small electric currentsare induced that circulate around the rope axis within and between thewires. These eddy currents also alternate and produce their own magneticfields which tend to oppose that from the primary field. This oppositionproduces a phase shift between the peaking of the magnetizing currentand that of the sensor coil voltage. Built-in circuits in the instru-mentation utilize the phase shift to produce a second data trace. Thefirst data trace, called X, is essentially proportional to the axialcomponent of the flux field in the rope, and therefore, measures loss ofmetallic area. The second trace, called R, is proportional to themagnitude of the eddy currents and reflects conditions within the ropethat cause changes in the eddy currents. Corrosion products or laytightening or loosening will affect the passage of eddy currents. Thus,by comparing the X and R traces, wear and corrosion can usually bedifferentiated.

Unitized AC/DC Unit

The unitized AC/DC unit uses a sensor head having strong permanentmagnets to saturate the wire rope with magnetic flux. This is similarto the individual DC unit; however, the means of sensing the faults inthe rope is different. Hall effect sensors are used to detect faults.

4

Hall effect sensors are solid state devices which can detect andaccurately measure magnetic fields. Figure 8 shows a sketch of a sensor.Electrical wires are bonded to all four sides of a semiconductor chip.A constant current is passed between two opposing edges. The other twoedges develop a potential difference when the semiconductor chip isplaced in a magnetic field. The potential difference developed by thesensor is directly related to the strength of the flux field. Staticmagnetic fields can be measured; this is a feature not available in theindividual AC/DC units. This means that ropes traveling at extremelyslow speeds can be inspected, which is desirable when trying to pinpointa fault location.

Figure 9 shows the placement of Hall effect sensors in the Magnographsensor head which clamps around a wire rope. The Hall effect sensorslocated between the poles of the magnets pick up flux leakage, whichindicates broken wires or other local faults (or LF). The Hall effectsensors at the poles of the magnets measure the quantity of flux "flowing"into the wire rope. When the cross-sectional area of steel changes, sodoes the flux "flowing" into the rope; thus, loss of metallic area (orLMA) is measured.

TESTS

Laboratory Test

A laboratory test was conducted on a new steel wire rope, 6 x 19independent wire rope core, 1-1/8-inch diameter, extra improved plowsteel, right lay hoisting rope, which contained man-made faults. Indi-vidual AC/DC units were tested along with the Ilagnograph unit (Figure 10).

Data from the tests are shown in Figures 11 through 13. The numberson the traces identify the various faults, which are explained as:

1. "Broken" outside wire: A piece of wire 2 inches long (cutfrom the end of the rope) was taped into the groove betweentwo strands.

2. Corrosion: A section of wire rope about 18 inches long wassoaked in nitric acid for 35 minutes to produce mild corrosionof the steel.

3. Broken outside wire: A single wire on the outside surfacewas cut with a chisel.

4. Wear: A hand-held power grinder was used to wear away steel.

5. "Broken" inside wire: A piece of wire 1 inch long (cut fromthe end of the rope) was inserted in the middle of the wirerope.

Figure 11 shows the data from the individual DC unit. The toptrace presents the data for sensor coils A and B as the square of thesum (A + B)2 and the bottom trace as the sum A + B. The broken wires,numbers 1, 3, and 5, were detected well. Note that the direction of thesignal spike is in the opposite direction for the added wires, numbers 1and 5, than that for the cut wire, number 3.

5--V

Corrosion pitting and local, uneven wear cause flux leakage; thesefaults (numbers 2 and 4) were detected. Fault number 2 appears to be alarger wire break (or the sum of several wire breaks) than that offaults 1 and 3; however, corrosion can usually be distinguished frombroken wires because of the length of rope over which corrosion occurs.This test rope had an unrealistically short length of rope with corrosion.

Figure 12 shows the data from the individual AC unit. Little datacould be obtained from the AC unit because the equipment was designedfor field test situations. The full-scale LMA trace was factory set at25%; hence, with the pen set in the middle of the trace a ±12.5% loss ofmetallic area could be recorded. Faults 2 and 4 had LMA readings around0.5% which were too small for the AC equipment to record. The chartpaper speed was also factory set at one speed, 2 mm/sec, which is appro-priate for long lengths of rope (thousands of feet) but not the shorttest length of wire rope. The bottom R trace, which gives a relativeindication of magnetic permeability, did not produce meaningful dataduring the laboratory test.

Figure 13 shows the data from the Magnograph unit. The top traceis LMlA data and bottom trace LF data. The LMlA full-scale setting wasset at 5%; hence, faults 2 and 4 were both recorded as having an LMA of0.5%. The LF trace was essentially identical to that of Figure 11.Interpretation of data is made easier by having the LMA and LF tracestogether. The corrosion faults, 2 and 4, can be distinguished from thebroken wire faults of 1, 3 and 5.

Field Tests

Manitowoc Crane: The load line to a Manitowoc crane, series 4100,having a lift capacity of 300 tons, was inspected using individual AC/DCunits and the Magnograph unit. The wire rope was a 6 x 19 independentwire rope core, 1-1/8-inch diameter, improved plow steel, right layhoisting rope. Approximately 600 ft of wire rope was inspected.

The individual DC unit produced a trace of local faults that showedthree definite defects and two probable defects. The signal size forthe probable defects was larger than background noise but not as largeas the other defect signals. No attempt was made to try to locate thedefects in the wire rope because: (a) there was no means to pinpoint thedefects, (b) a length of rope from 3 to 5 yards long would have had to becleaned and searched, and (c) inspection by the Magnograph was to followwhere the defects could be pinpointed.

Prior to using the individual AC unit, the wire rope was degaussed.The process was not only slow but also unsafe. The design of the degaussingequipment required that the unit be held by hand as the rope movedthrough at a maximum speed of 50 fpm (Figure 14). The close proximityto a moving wire rope while the inspector's body became fatigued holdingthe degaussing box was unsafe. In addition, the copper strap clamp overthe wire rope became hot from resistance to current flow.

In some situations, the AC unit could be used before the DC unit sothat degaussing may not be necessary. However, any stray magnetic fluxpicked up by sections of a wire rope produce erroneous readings on theAC trace; those sections of wire rope, and only those sections, need tobe degaussed. If at any time previously (meaning months and years), thewire rope was inspected with a DC unit, then the wire rope needs to bedegaussed.

6

The AC unit was set up on the wire rope, but an inspection was notcompleted. Data were unusable because clean 115 VAC line power was notavailable. A generator source and available shore power source weretried; however, time was not sufficient to try other sources. Electricalequipment problems were encountered.

The Magnograph unit was the equipment tested last. Degaussing wasnot necessary prior to using the Magnograph unit. The local fault traceshowed three distinct defects while the loss of metallic area traceshowed negligible wear or corrosion. After locating the defects, theywere identified as: (a) a 1-inch-long piece of wire that had been com-pletely sheared off, (b) peening from the cable hitting the side of thedrum, and (c) a nick on an outside wire.

The defects coincided with those from the DC unit in signal sizeand relative location along the length of the wire rope. The Magnographunit showed absolutely no indication of the two probable faults shown onthe DC trace. Standard procedure calls for a wire rope to run throughthe sensor head twice so that signal peaks from stray background noisecan be eliminated as probable defect signals. Two runs were made withthe DC unit and the probable defect signals appeared both times. Tworuns were also made with the Magnograph unit and no indication of thequestionable defects were found. It is the opinion of the authors thatthe probable defects did not exist. Subsequent testing indicated thatthe signal strength for the probable defects was too small to be faults.

Floating Crane: A floating crane, YD171, having a lift capacity of350 tons, is stationed at the Long Beach Naval Shipyard (Figure 15).The crane was built in Germany in 1941 and brought to the United Statesafter WW II. Since 1946, the records show that the main wire ropes havenot been replaced.

The crane has a left and right main wire rope which service separatehooks of 175 tons lift capacity. Both of the wire ropes were scheduledfor replacement by using "new" wire ropt that came with the crane. TheCivil Engineering Laboratory inspected the main wire ropes and thereplacement wire ropes with the Magnograph equipment.

Both main wire ropes were 8 x 36 construction, 1-7/8 inches indiameter; however, the left main rope had a fiber core and the rightmain rope had an independent wire rope core. The replacement wire ropeswere of the same size as the ropes in use and both had an independentwire rope core.

Each wire rope was 930 yards long. For the wire ropes on thecrane, the middle 730 yards were inspected. At the drum end, a lengthof about 100 yards was wrapped on a drum, and at the boom end, about 100yards was inaccessible for safe working conditions.

The results from the inspection found one broken wire in the rightmain wire rope and a loss of metallic area of about 1.5% from wear andcorrosion in both main wire ropes. However, the left main wire rope,which had a fiber core, showed more evidence of corrosion pitting in theLF trace than the right main wire rope. In any event, 1.5% loss ofmetallic area was low (10% LMA is the level for wire rope replacement),so the wire ropes were in good condition.

The replacement wire ropes did not have any broken wires, but theydid have a loss of metallic area on the order of 1.5%. Sections of wirerope showed corrosion pitting to be greater for the replacement. ropethan for the rope in use. This finding indicated that the maintenanceof the wire rope on the crane must have been excellent over the years.

7

As an outcome of the nondestructive test, the wire rope on thefloating crane was determined to be in a safe, usable condition and neednot be replaced.

COMPARISON OF FEATURES

Table 1 is a summary of the instrumentation and operational featuresof the Magnograph unit and the individual AC/DC units. The Magnographunit uses fewer components to conduct a test. Three pieces of equipment,the sensor head, electronics section, and recorder section, are requiredto obtain LF and LMA data. To obtain the same information, the individualAC/DC units requires five pieces: DC sensor head, DC electronics section,degausser unit, AC sensor head, and AC electronics section.

The Magnograph unit has two technical features that are superior tothat of the individual AC/DC units. First, the LF and LMA data aredisplayed on the same brush chart recorder trace. This permits a morecomplete interpretation of the results. It is a definite aid to inexpe-rienced personnel in determining what types of defects the data signalsrepresent. Second, the sensor head picks up defect signals at slow wirerope speeds. This provides a means to quickly locate the defects forvisual inspection.

SUMMARY

Laboratory and field tests were conducted on NDT equipment for wirerope. A unitized AC/DC unit was found to provide several importantfeatures that individual AC/DC units were technically unable to provide.Those features were:

(a) A range of operating speeds from 0 to 500 fpm for wire ropetraveling through the sensor head. The extremely slow speedsare important for locating defects for visual inspection. Anindividual DC unit is limited to 50 to 500 fpm.

(b) Data displayed on a two-channel brush chart recorder thatshowed concurrently the local faults and the magnitude of lossof metallic area. Data interpretation is aided by these twoimportant parameters being displayed together. IndividualAC/DC units must measure local faults and loss of metallicarea separately by using different equipment for each parameter.

The unitized AC/DC unit, developed by Noranda Research Centre andcalled the Magnograph unit, performed well in inspecting metallic wireropes.

RECOMMENDATIONS

Based on the test and evaluation work reported herein, the unitizedAC/DC unit has two important features over that of individual AC/DCunits for Navy applications. Those features are listed in the summarysection. It is recommended that the Navy procure unitized AC/DC equipmentfor meeting its needs in inspecting metallic wire rope.

8!

In anticipation of Navy shipyards and other operational facilitiesproviding their inspectors with NDT equipment, it is recommended that

further tests be conducted using the Magnograph unit so that a com-pendium of defect signals can be published to assist inspectors in data

interpretation. The operational limits of the equipment need furtherinvestigation, and this information also needs to be conveyed to inspectorsby an operator's manual document.

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Figure 1. Conventional method for inspector to locatebroken wires on outside of wire rope.

N , S

Figure 2. Saturation of wire rope with lines of flux.

1 3

Figure 3. Lines of flux.

Figure 4. Flux leakage at location of broken wire.

movement of

conductor

Figure 5. A current is created in a conductormoving through lines of flux.

14

movementof wire

Figure 6. Search coils pick up radial componentof flux leakage.

j primary coil

secondary col alternat ingci 1 mgnetic

Figure 7. The basic principle of the AC method.

Figure 8. Sketch of a Hall effect sensor.

N N

/ fall effect

/ 0

F i go r 10(. SiLLp1 of IMagnograplinindestruc ti ye tes t eqo ip)meiitfor at tue-t ()n at rran, wi re

17 1 ' I L' cL ronl ic and r( to rcu r-. 'CiO(1 ionrc inl foreground andsen-sor wa'id in background.

......................

Gould Inc. Instrument Systems Div io BRUSH ACCUCHART

Figure 11. Data from laboratory test on anindividual DC unit.

*~.. ...... ....

F i gUre 12. Data f romLalhuraturv test on

BRUSH ACCUCHART Gould Inc., Instrur ani indiv idual AC unit.

...... . K.. 4 I ------

....... .......................................

t t -1 - - j- t - + -

1L .. .i . ... ...... .... .. -- -

7 ..... .... ..

+ -- A A i 4A t ±± .L Iivp Al Ah A ne

V.T.h.... ....H I..

ti .. t .

. ......... ...... i...

Figure 13. Data from laboratory test on theIagnograph unit.

Figure 14. Degaussing wire rope between tests using

individual DC and AC units.

Figure 15. Floating crane at Long Beach Naval Shipyard.

19

Ii

Appendix

DESCRIPTION OF NORANDA'SMAGNOGRAPH EQUIPMENT

FRONT PANEL CONTROLS - ELECTRONICS (Figures A-i and A-2)

I. Power ON/OFF Switch (should be OFF during battery charging)

2. Powerline/Mains connection

3. Sensor Head Connection (NOT necessary during playback mode)

4. Chart Recorder Connection

5. Battery Check Switch:

When depressed, battery state is indicated on LMAanalog meter (6).

6. LMA Analog Meter:

Displays same signal as the chart recorder LMA channel

during record and playback. May also be used for zeroadjustment.

7. Metric/English Switch:

Selects either SI or Imperial Units as the basis of allmeasurements.

8. Rope Direction Switch:

Changes counting direction of Measured Length Up/DownCounter.

9. Loss of Metallic Area (LMA) Gain Potentiometer:

Used to set the gain of the LMA Channel according to thesize and type of rope being tested.

10. LMA Zero Potentiometer:

Used to zero the LMA Signal before commencing a test.

11. Offset % LKA Switch:

Used during a test (if necessary) to move the L14A zeroby a fixed percentage.

20

12. Local Fault (LF) Gain Potentiometer:

Used to set the gain of the LF Channel according to thesize and type of rope being tested.

13. LF Zero Potentiometer:

Used to zero the LF signal before commencing a test.

14. Compression Band Division Switch:

Used to reduce the rope noise component of the LF signal.

15. LF Analog Meter:

Displays similar signals to the Chart Recorder LF channel,during record and playback. Also may be used for zeroadjustment.

16. Static/Dynamic Switch:

Normally used in Dynamic mode for rope speeds 50 to500 fpm. Below 50 fpm, static mode should be selected.

17. Measured Length Counter (and Reset):

Displays distance traveled along a rope. Counts bothUp and Down. Can be Reset using the push button.

18. Wire Rope Speed:

Displays the rate of movement of the rope through theSensor Head.

19. Tape Counter (and Reset):

Indicates position on the tape cassette.

20. Record/Play Switch:

Selects either Record or Playback mode for both thecassette recorder and the internal electronics.

21. Cassette Tape Recorder with Standard Controls:

Record ButtonTape RunRewindStopFast Forward

22. External Battery Connections

23. External Battery Power Indicator (illuminates if connectionis correctly made)

21

FRONT PANEL CONTROLS - CHART RECORDER (Figure A-3)

1. Power Line/Mains Connection

2. External Battery Power Indicator Light (illuminates if connec-tion is correctly made)

3. External Battery Connections

4. LF (Local Fault) Channel Input (for test purposes only)

5. LF Channel Pen Position

6. LF Sensitivity Variable Potentiometer:

Should be fully clockwise

7. LF Sensitivity Switch:

Should be set at 10 mV for Magnograph recordings

8. LF Channel Input Shorting Switch

9. LMA Channel Input Shorting Switch

10. Chart Speed Selectors:

Used when TIME BASE mode is selected

11. Battery State Indicators:

Battery needs recharging when indicator enters the redarea

12. LMA (Loss of Metallic Area) Sensitivity Switch

13. LMA Sensitivity Potentiometer:

Should be fully clockwise

14. LMA Channel Pen Position

15. LMA Channel Input (for test purposes only)

16. Electronics Section Connector

17. Proportional Drive Selector:

Selects chart recorder timebase or proportional drive

I)')iii~ip - 0

21o1

10 MAGNOGRAPH

'Y.'m

Figuire' A- 2. Vieow of Magriog raph sens or head.

chartp

m

e

0 ff 1 2 10

5 50 -a~keven

L wJ w J LJ PSL A

(D0

batte0

sens~t-tv s nv

I0

rA -1 t -LD i UR CSI "2

4

DISTRIBUTION LIST

AAP SAVORDS I A IND) 1)1)1 I' PW l:NURNGi IV,\ McAlester. OKAFl) (AI-ITLI)). Wright- Patteison I l I AF lech Office (M~gt & Ops). I vndall. IL: Al-TCXR. I vndall FL

('ESCtl. Wright -Pat terson:, 110 l'actical Air ('nid 1R. F. Fisher). L-angksN AF13 VA: IIOAFES('DEMM.I'Nndall AFB, F: MIAC DE)I* (Col. 11, Ihonipsin I Scott. iI.: SAMSO MNNI). Notion AFB (A. Stintolbrar\. (Ilttt NE

ARC IICSLUBI-AB (Code 54. Sin D~iego. CAARMY ARRAI)(ONI. Dover. NJ: BMDS('-REIII (1. Mclellan) Huntsville Al.: I)AIN-( WL-M (1.1 C D

Binning). Washington I)C: l)AEN-FEL1-E (J. Ronan), Washington I)C: I)AEN-NIPE-l) Washington DC':DAEN-MPU. Washington DC: ERAD)(OM Tecch Supp D~ir. (DELSD-L) Ft. Monmiouth, NJ,IIQ-DAEN-MPO-B (Mr. Price): Tech. Ref. Di%., Fort fluachuca. AZ

A\RMY - CERL Librarv. Champaign 11.ARMY COASTAL. ENGR RS('II (EN Fort Belsoir VA. R. Jacho%\ski. Fort Belvoir VAARMIY COE Philadelphia Dist. (LIBRARY) Philadelphia. PAARMY CORPS OF ENGINEERS MRD-Eng. D~iv.. Omaha NE. Seattle Dist. Librar'.. Seattle WAARMY CRREL A. Kovaes, Hanover Nil: C'onstr. Engr Res Branch. (Aamot)ARMIY CRREL R.A. EatonARMY DARCOM A.MCPM-CS 01. C'acti. Alexandria VAARMY ENG DIV IINDED-CS. Huntsville AL: HNDED-SR. Huntsville, Al,ARMY ENG WATERWAYS E.XP STA L~ibrary. Vicksburg MISARMY ENGR DIST. Library. Portland ORARMY ENVIRON. HYGIENE AGCY Water Cual Di% (Doner). Aberdeen Pro% (Ground. 1,1)ARMY MAT SYS ANALYSIS A(-I Code DRXSY-CM IM Ogorzalek) Aberdeen Prosing (irnd MDARMIY MATERIAL.S & MECHANICS RESEARCH C'ENTER Dr. Lenoe. Watertowsn MAARMY MOBIL EQUIP R&D COI (Code DRXFB-MR Fort Belvoir VA: F Stiira Fiirt Belv~oir VA: Fuel

finding Equip Br.- Ft Belsoir. \'A: Mr. ('esaseo. Fort Belvoir MDARMY MTMC Trans Engr Agene% ID) F Eiehhorn) Newport News. VAARMY TRANSPORTATION SCFHOL IMA) T Sweeney, Code ATSP CD-]E Fort Eiustis VA: V Quinbv (Code

ATSP-CPO-MS Fort Eustis VAARMY TRNG & DOCTRINE CMD Code ATCD-SP-L Fort Monroe VAASSTr SECRETARY OF THE NAVY Spec. Assist Energy (Leonard), Washington. DC. Spec. Assist

Submarines. Washington DCBUREAU OF COMMERC'IAL FISHIERIES Woods Hlole MA (Biological Lab. Lib.)BUREAU OF RECLAMATION ('ode 1512 (C. Selander) Denver COCENTER FOR NAVAL ANALYSES Doeument Center (Darke). Arlington, VA('INCLANT Civil Engr. Siipp. Plans. Ofr Norfolk. VACINCPA(' Fac Engrng Div (144) Makalapa. ifCNAVRES Code 13 (Dir. Facilities) New Orleans. LA('NM Code (13462. Washington DC: ('ode 0143 Washington DC: Code MAT-tI8T3. Washington. DC('NO Code NOP-964. Washington DC': Code OP 3231. Washington 1)C: Code OP 4015, Washington DC'% ('ode OP

4)15, Wasington DC: Code OP 414 Washington DC: Code OP 414. Washington DC: ('ode OP 97 WalshintonD(%' Code OP 97 Washington D(': ('ode OP 997 Washington DC(' Code OP 987 Washinton D(': Code OP323Washington DC: Code OPNAV 091324 (H) C'ode OPNAV 22. Wash DC: ('ode OPNAV 23. Wash D)C:OP987J (J. Boosman). Pentagon

('OMCHPAC Operations Off. Makalapa fiICOMDEVGRUONE San Diego, ('A('OMFAIRWESTPAC Security 01Cr. Misawa JapanCOMFLEACT. OKINAWA PWO, Kadena. Okinawa('OMNAVBEACHPHIBREFTRAGRU ONE San Diego CACOMNAVMARIANAS Code N4, GuamCOMOCEANSYSPAC SCE, Pearl Hiarbor HICOMSUBDEVGRUONE Operations Offr. San Diego. CANAVSURFLANT Norfolk. VANAVSURFPAC San Diego. CA(OMOPTEVFOR CMDR. Norfolk. VA: Code 7011A, San Dtego. (A

j 25

1)1FFI .NSI, IN I LIlIGI N( 1: A( I N( Y Dn.. W~ashington DC(1)1 I 1it Arm% Lgistics Skig ('enter. Fort Lee, VAl)NA SITL. Washington DC(D)011 Dr (Cohen: Lit iek. Richmiond. \%A1) FIC lDclense Ilcchnicail Info (ir Alexandria. VA1)IN S RI) Anna I ab (Code 1175) An napolis NI I): Arna lab (Coide 1175) Annapolis NilI): Anna Lab C ode

1568) Annapolis MDD INSRD(' Code 172 (NI. Kren.,ke). Bethesda MlD1)INSRD(' Code 2785 I Bloomiquist . .5 i iapolj, MD C I) ode 284 (A. Rutolo I. A nnapol is MD)1) I'NSRD' (Code 4111 (R. (jicrich). Bllcda NIl)DTNSRDC Code 4121 (R. Rivers), Annapolis. MilD'INSRDC (Code 42, Bethesda NilDTNSRI)( (Code 5221 (Library). Annapolis MDFL T(OMBATrRACENLANT l'WO. Virginia licb VAEMFLANI' CEC 0thr. Norfolk VAFMFPAC C0 Pearl HarborGSA Fed. Sup. Serv. (FMBP). Washington DCFICU ONE CO, Bishops Point. HIKWAJALEIN MISRAN BMDSC-RKL_-CLIBRARY OF CONGRESS Washington, D(C (Sciences & Tech Div)MARINE CORPS BASE Camp Pendleton (CA 920155: (Code 43-260, (Camp Lejeune NC: First Service Support

Group Camp Pendleton CA: M & R Division. Camp Lejeune NC: PW() ('amp Lejeune NC': PWO. ('amp SD. Butler. Kawasaki Japan

MARINE CORPS HQS Code LFF-2. Washington DCM('AS Facil. Engr. Div. Cherry Point NC: CO. Kaneohe Bay HIt: Code PWE. Kancohe Bay HI: ('ode S4.

Quantico VA: PWD, Dir. Maint. (Control Div., Iwakuni Japan: PWO Kaneohe Bay Ill: PWO. Yuma AZMCDEC NSAP REP. Quantico VA: P&S Div Quantico VAMCRD PWO. San Diego CaMILITARY SEALIFT COMMAND Washington D('NAD Engr. Dir. Hawthorne, NVNAF PWD - Engr Div. Atsugi. Japan: PWO Sigonella Sicily: PWO. Aisugi JapanNALE OINC. San Diego. CANARF Code INM). Cherry Point. NC: Code 640. Pensacola FL: Equipment Engineering Division (('ode 6IIKX))

Pensacola. FLNAS CO. Guantanamo Bay Cuba: Code 114, Alameda CA: Code 183 )Fac. Plan BR MGR): Code 187WM.

Brunswick ME: Code 18U (ENS P.J. Hickey). Corpus Chbristi TX: Code 6234 (G. Trask). Point Nlugu CA:Coide 70. Atlanta. Marietta GA: ('ode 8E. Patuxent Ri',.. MD: Dir. Maini. (Control Div.. Key West FL: D~ir.Li. Div., Bermuda: ENS Buchhiilz, Pensacola, FL: lakehurst. NJ: Lead Chief. Petty Offr. PW Sell HelpDiv. Beeville TX: OI('. (BU 417, Oak Harbor WA: l'W (i. Nlaguirc). C'orpus Christi.TX; PWD Maint.Cont. Dir.. Fallon NV: PWD Maint. D~iv._ New Orleatis. Belle (Chasse LA: PWI). Maintenance ControlDir.. Bermudla: PWD. Willow Grove PA: PW() Belle Chiasse. LA: PWO ('base Field Beeville. TX: PWOKey West FL.: PWO. Dallas 'rX: PWO. Gjlenview\ IL: PWO. Kingsville TX: PW(). M~illingtion IN: PWO..Miramar. San D~iego ('A: PWO.. Moflett Field (CA: ROI('( Key" West FL.: SCE Lant Fleet Norfiilk, VA:SC'E Norfolk. VA: SC'E. Barbers Point HI: Securits' Offr, Alameda ('A

NATL BUREAU OF STANDARDS B-348 BR (Dr. (Campbell), Washington DCNAIL RESEARC'H COUNCIL Naval Studies Board, Washington DCNATN AVMEDCEN PW() Bethesda. MD)NAVAC-r PWO. London UKNAVAC-I DEl PWO. Holy Lock UKNA VAE ROSPREGMEDCEN SC~E, Pensacola FL_NAVAVIONICFAC PWD Deputy Dir. 1) 71,1 Indianapolis. INNAVCIIAPGRV. (C.) Williamsburg VANAVCOASTISYS(EN (ode 719, Panama City. Fl,: (ode 772 IC B Koesy) Panamna ('it ElNAVCOAS'ISYSTCTR CO. Panama City FL.: (ode 423 (1). Good). Panitna (its FL: ('ode 713 1.J Quirk)

Panama C ity. Fl. Code 715 (J. Mit I leman I Panama ('ity. Fl . L ibrar\ Panama ('its' Fl,NA%'( ONIAREAMSIRSFA (OdeC W-60i2, Honolulu. Wkabimka , Ill. NI,iint (Control D~i% . 5ahiawa. Ill. PWO.

Norfolk VA. PWO. Wahiawa fit: S( ' Unit I Naples Italy

26

\.N'('OkMNISl'A (O. San Migul.C R. P. ('ode 401 Nea Makri, Crce:c PWO. Exinouthi. Australia: PW). FortA mador C'anal Zone

NANI.DIR.\PROI)EVCIN 'Lech. Iibrar\N'AN LIDUFRACIN Frig lDept (('ode 42) Newport. RIN NNI'IXSYSC()M (OIC PNIE-l24-6l. Washington DCNAN INVIRI III'I('EN (O. Norfolk. VAN.\VTO1)A( (Code 60U5. Indian Ilecad Mil)NAN'F.'N P1WO. Cape H atteras. Buxton N(% PW(). ('enteriville Bech. Ferndale (W: PWO. (m1ainNNVFAC l'WO. lewes DENAN'FA (WO(' ) ('ode 1143 Alexandria, VA: (ode 044 Alexandria. VA: C(ode 0)451 Alexandria. VA: ('ode

1ii (I). Potter) Alexandria. VA: ('ode 0453C, Alexandria. VA: (ode 0)454B Alexandria. Na: ('ode 0140:(ode 04611) (V NI Spauldi ngz) Alexandria. VA: (ode 0183 Alexandria. VAW (Code 04135 Alexandria. VA:Code 016. Alexandria VA: ( ode 110I Alexandria. NAW ('ode 1)1112 IiJ.e Lcan is) Alexandria. VA: Code 1113IM (arr) Alexandria. VA: ('OLIC 1113 (T'. Stevens) Alexandria. VA: (ode 1113 Alexandria. VA: Miorrison

Yap. Caroline Is.: P WV Brewer Alexandria. VA: PC-2 Alexandria. VANAVFA('ENGCOkM - ('IES DINV, Code [III Wash. DC: ( ode 4102 (1) Seheesele) W\asl'ington. OC: (ode 4103

I II. DeVoe) Wash. D(: (Code 405 Wash. D)C: ('ode FPO-l Wash. D)C: ('ode FPO-l II'. Wash. D)C: C(odeITO- I L,. Wash. DC;' (Contraets. ROICC. Annapolis Nil): FPO- I (Spencer) Wash. I)(': FPO- I Wash. DC

NAVEAUENGCONI - LANEF lDIV. (Code IOA. Norfolk VA: Fur. BR IDeputy Dir. Naiples Italy: EuropeanBranch. New\ York: RD'I&EL() 1112, Norfolk VA

NAN'FA(EN(W(OM - NORTH D)IV. (Boretsiy) Philadelphia. PA:O CO LI(Cd (1911 )(L)DR ATi Stewart): (Code10128, R DI& 7LI). Philadelphia PA ('odie Ill1 ('astranoxo ) Philadelphia. PA\: ('ode 114 (A. Rhoads)D~esign D~i\. ( R. Niasino). Philadelphia PA: ROI('(. (Contracts. (Crane IN

N AN'FA( ENG(COMI - PA(C DI1V. I Kyi) ('ode 11, Pearl IHarbor. Ill: ('oide 20H1 Pearl Harbor. Ill: ('ode 4042.RDF&E. Pearl Harbor ILL: Commander. Pearl Hlarhor. Ill

NAVI'ACENG('ONI 'SOUTH DIV. ('odte 90. RDT&ELO. Charleston SC.: ROIC 1('L)R R. Nioeller).C'ontraets.(Corpus C'hristi TIX

NAVFA('ENG('OM W XEST' DINV. 1112: 112: AROI(C (Contraets. rI'sent',ninc Palms CA: ('iide 014B SanBrunoi. ('A: 091' 20 San Bruno. ('A: RI)'I&ELO ('ode 20111 San Brutno. ('A

NAN'FA(ENGC(ONI ('ON'IRA("l AROICC. point Mueiu ('A: AROI('(. QUantieo. VA: Cotde 015. 'IRIDENI'.Bremerton WA: Dir. Eng. l)i%.. Exntouth. Australia: Eng lDiv' dir. Souithwecst Paic. Manila. PL: OI('('Southwecst Pac. Manila. PI: OIC(' ROI('C. Balboa ('anal ZLone: ROI('( AFE (mai: ROI('( LANi' DIV_.Norfolk VA: ROIC('. Diego Garcia Island: ROIC'(. Keflavik. Ieeland: ROI('(. Pacifie. San Bruno ('A

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28

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29

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ROLL)I NIVERSITY 01- RHIODE ISLAND) KIN( SiO N. RI IPAZiS): Nar-r.iegai,st RI IPcil Marine Sor IitLIN IVE RS iTY O F SO. (CALIFORNIA Ujus So. (alitUNIVERSITY OF lEXAS lust. Marine Sci (Librar%). P'ort Arkansas I XUNIVERSITY OF FEXAS At AUSTIN AUSlIN. IX HJIIOMPSON): Austin. IX N trccu(LINIVERSI- IY OF WASiIINGIlON Seattle "'A (MI SheriffL Dept of Ciji LEnr (D~r Nlattocki, Scalii WA

SEATILIE. WA (APPIED) PHYSICS LAB): SEAlILFIE. WA (N1FRciAN 1). SEIA I1 IL. ViA (0( 1 ANENG RSCHi LAB, GRAYL SEAIILE. WA (PACIFIC MARINE LNVIRON li IIALPI RNi. Sc,ittteWA (F. Linger): Seattle. WA Transportation. Constructiont & (ieuii. ii

UNIVERSITY OF WISCONSIN Milwaukee WI (Ctr ot Great Lakes Studies)VIRGINIA INST. OF MARINE SCI. Gloucester Point VA (library)AGBABIAN ASSOC. C. Bagge. El Segundo CAALFRED A. YEE & ASSOC. Honolulu itAMETEK Offshore Res. & Engr DivANISCO Dr. R. McCoy. Eric. PAARCAIR CO. D. Young. Lancaster OH

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30

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