Magnaflux Unit

8/15/2019 Magnaflux Unit

http://slidepdf.com/reader/full/magnaflux-unit 1/28

STANDARD OPERATING PROCEDURE AND SAFETY

GUIDE FOR MAGNANFLUX UNIT

(Located in Rm. C-23 Head Hall)

Prepared

July 28, 2010



ii

Table of Contents

1. Scope ........................................................................................................................................4

1.1 Objective ............................................................................................................................4

1.2 Regulations ........................................................................................................................4

2.Apparatus Overview and objective ...........................................................................................42.1 Apparatus overview ...........................................................................................................4

3. Hazards and control evaluation ..............................................................................................13

3.1 Possible fire event ............................................................................................................133.2 Ventilation ........................................................................................................................13

3.3 Kinetic, thermal & accoustic ............................................................................................13

3.4 Electrical ..........................................................................................................................133.5 General, physical & equipment concerns ........................................................................14

3.6 Access ..............................................................................................................................15

3.7 Training ............................................................................................................................153.8 Personal protective equipment .........................................................................................16

4. Operation ................................................................................................................................164.1 Qualified personnel ..........................................................................................................16

4.2 Experiment preparation ....................................................................................................164.3 Lab instructions ................................................................................................................17

4.4 Operating procedure .........................................................................................................18

5. Inspection and maintenance ...................................................................................................245.1 Operational & Periodic inspections .................................................................................25

6. Typical test .............................................................................................................................26

Appendix A: Operator - inspector guidance charts - Section III ...............................................27Appendix B: Operating manual for P- 90 ..................................................................................28



3

C-23, Head Hall floor plan



4

1. Scope

1.1 Objective

This standard operating procedure is intended to provide operating

instructions and safety information for the Department of MechanicalEngineering’ portable magnaflux unit located in C-23, Head Hall. Thisdocument is intended as a guideline and supplement to proper training that

must be provided by qualified personnel before the apparatus is operated.The aim of this document is to ensure that safe work practices have been

developed for the apparatus experimental work. This SOP is primarilyconcerned with the apparatus operating procedure, hazards involved with its

operation and safety precautions that must be taken to avoid injuries.

1.2 Regulations This document has been developed in accordance with the EnvironmentalHealth and Safety Office of the University of New Brunswick.

2. Apparatus Overview and Objective

2.1 Apparatus overviewThe magnaflux unit is an extremely compact integral unit of all aluminumconstruction. All operating controls and output terminals are located on the

front panel. The magnetizing cables are equipped with prods for circular

magnetization and can be wrapped around the test specimen to form a coilfor longitudinal magnetization. The power controller unit transforms the

high voltage, low amperage line input, to low voltage, high amperage half

wave D.C. for magnetizing. It also furnishes low voltage, high amperage

A.C. for magnetizing and demagnetizing.The magnetizing and demagnetizing current is controlled by current

control knob on the power controller unit and can be read on ammeter.Half wave D.C. is obtained by connecting the magnetizing cables to COM

and HWDC outlets on power controller unit. Similarly, A.C. current is

obtained by connecting the cables to COM and A.C. outlets. One of the prod has a control switch built in to the handle. It controls the flow ofmagnetizing current through the prods. On pressing the switch magnetizingcurrent flows through the prods, magnetizing the test specimen and releasing

the switch stops the magnetizing current flow through the prods. The controlswitch is connected to the control cable outlet of power controller unit via

prod control cable.



5

Figure 1: power controller unit controls and output terminals



6

Figure 2: Apparatus magnetizing prods and test specimen



7

Figure 3: Prod control switch



8

Figure 4: Power controller unit front panel

The test specimen is magnetized by firmly holding the two prods to itssurface. While the test specimen is magnetized, dry magnaflux powder

(containing small magnetic particles) is applied on its surface using

magnaflux dry powder blower. The dry magnaflux powder is available indifferent colors to give a good contrast with the test specimen being inspected.The magnetized test specimen is demagnetized after completion of test and

field indicator is used to determine the presence of magnetic field around thetest specimen.



9

Figure 5: Magnaflux dry powder blower and field indicator



10

Figure 6: Magnaflux portable unit components overview

The portable magnaflux unit is electrically powered and its power controllerunit is connected to main power supply via electric cable.The objective of the apparatus is to find those defects in test specimen which

are not otherwise visible to the naked eye. The magnaflux unit uses magnetic particle inspection method to find surface and sub surface defects. This

inspection is important to the quality of the finished product, and in findingdefects as early as possible in manufacture, to avoid wasting machining and

processing time on defective material. The operator may use dry or wetmethod to do the magnetic particle inspection of test specimen using

magnaflux unit and we only use dry method to carry out this experiment.



11

Figure 7: Magnaflux unit main power supply



12

Figure 8: Circular magnetization of test specimen

Figure 9: Longitudinal magnetization of test specimen

Please refer to Appendix “A” (Operator - inspector guidance charts - SectionIII, How magnaflux works) to see the details and description of how the

apparatus works. Also refer to Appendix “B” (Operating manual for P- 90)to see the details of apparatus installment, controls and operation.



13

3. Hazards and Controls Evaluation

3.1 Possible fire event

The apparatus is associated with elevated temperatures. In the event of fire,

evacuate the room immediately. Pull the nearest fire alarm (see C-23 floor plan). Should you return to attempt to extinguish the fire, do not do so aloneand make one attempt only and if unsuccessful leave immediately. If

successful stay at the scene and have someone alert Security (ph. # 4830)and Campus Safety (ph. # 5075). Please refer to C-23, Head hall floor plan

to see the locations of fire extinguishers, fire alarm pull station and first aidkit.

3.2 VentilationThere are no ventilation fans in room C-23 for room ventilation. The room is

centrally ventilated and its atmosphere is comfortable as fresh air is being

introduced at all times into the room. Proper ventilation system is not arequirement for the operation of magnaflux unit.

3.3 Kinetic, Thermal and AcousticThere are no moving parts associated with the apparatus so it does not pose

any kinetic threat to the user.The apparatus is associated with elevated temperatures so it poses thermal

threat to the user. The magnetizing current flowing through the test

specimen heats it up and the user should wear safety gloves to hold the testspecimen. The prods must be held firmly at 90 degrees against the testspecimen surface to prevent arcing and the user should wear safety glasses

while doing the test with magnaflux unit. The magnetizing cables carry highamperage current so the apparatus should be checked regularly for bare,frayed or cut magnetizing cables to prevent any serious burn/injury to the

user.The magnaflux apparatus is not associated with any acoustic hazard.

3.4 ElectricalThe magnaflux unit is electrically powered and it does not pose anyelectrical threat to the user, if handled carefully. Do not, however come into

contact with bare copper prods when they are energized. Make sure all otherlab occupants are clear off the test area before the prods are energized.

Always check the apparatus for bare, frayed or cut electrical cables before



14

operating it. Please see figure 7 to see the main electrical outlet powering theapparatus.

3.5 General, physical and equipment concerns

Hold the two prods parallel to the crack when magnetizing the test specimencircularly to detect the defect/crack easily. Holding the prods parallel to the

crack will cause the magnetic field lines to intercept the crack/defect perpendicularly which will make the defect more prominent to the user.

Figure 10: Prods held parallel to the defect

Similarly in longitudinal magnetization current is passed parallel to

the direction of defect and magnetic particles are attracted to the

defect to form an indication to indicate crack/defect.

Figure 11: Current passed parallel to the defect (Longitudinal

magnetization)



15

While magnetizing the test specimen, apply/dust the dry powder gently andlightly to the magnetized area. Watch for indications to form as the powder

is applied.Gently blow off the excess dry powder, while the magnetizing current is still

flowing. Keep the current flowing through the test specimen until the excess powder has been blown off.

Press and firmly hold both the prods at 90 degrees to the surface of testspecimen to prevent arcing. The magnetic field strength can be increased or

decreased by adjusting the current control knob to vary the current flowthrough the test specimen. Increase the amperage flow to increase the

magnetic field strength and decrease for decreasing magnetic field strength.Use half wave D.C. and A.C. current for magnetizing the test specimen butonly use A.C. for demagnetizing the test specimen.

Wear safety glasses and safety gloves while doing the test with magnaflux

unit. Safety glasses prevent any small magnetic particle to enter the user’seye and safety gloves prevent the user from getting any serious burns sincethe test specimen becomes hot while doing the test and electric cables carry

high amperage current.To avoid overheating and consequent damage, a maximum duty cycle of 2

minutes “ON” and 2 minutes “OFF” must be adhered to when operating atrated output (750 amperes). Keep any electronic devices clear off the test

area to prevent accidental magnetization.

3.6 Access

All personal in the C-23 laboratory should be preauthorized by the faculty in

charge or under the supervision of authorized personal (lab technician orteacher assistant). No person other than the faculty in charge or specifically

authorized personal are permitted to make alterations to, or run experimentswith the portable magnaflux unit.

3.7 TrainingAll individuals using the portable magnaflux unit shall be required to receivetraining in the proper operation and maintenance of the apparatus and its

controls. Training will include such topics as the complete operation andcontrols of the magnaflux unit. Training programs shall be administered by

qualified personnel at UNB.



16

3.8 Personal Protective Equipment

Following personal protective equipment is mandatory while using portablemagnaflux unit:

1.

Safety glasses

2. Safety gloves

4. Operation

4.1 Qualified PersonalThese notes in the operation section will provide a guideline to theindividual that has been trained by a qualified personal to operate the portable magnaflux unit. Only after the individual has been trained and feels

confident with the apparatus operating procedure should he attempt tooperate the portable magnaflux unit using these notes. Do not proceed if you

are not properly trained or are unsure in any manner of the safety operation

and safety concerns.

4.2 Experiment preparation

Following steps should be carried out to prepare for the experiment:-

1. Clean the surface of test specimen using cloth or cleaner if available

2.

Connect one of 15 feet 4/0 cable to HWDC or A.C. output terminal (seefigure 1) as desired and the other cable should be connected to the“COMMON” output terminal

3.

Plug in the prod control cable (see figure 1) in to the control cable outlet

4.

Plug in the power cable of magnaflux unit to the main electrical outlet

(see figure 7)

5.

Fill in the dry powder blower with magnaflux dry powder (smallmagnetic particles)



17

Figure 12: Preparing for the experiment

6. Place the test specimen on a white sheet or paper to collect the blown

off dry powder instead of wasting it.

4.3 Lab Instructions

4.3.1 Instructor ResponsibilitiesThe SOP of portable magnaflux unit should be read and understood. Thisdocument provides all the necessary information regarding the apparatus

operation, hazards involved & safety precautions to be taken while using



18

apparatus. The lab instructor shall remain in the room while the experimentis in progress. After the full students group has assembled and before any

explanation has begun the instructor should relay all safety precautions andhazards as outlined in section 3. Inform them that they must contact the

instructor should any problems or concerns arise during the experiment.Make the group aware of the fire extinguisher locations, fire alarm pull

station and exits. Any student from the group missing his any personal protective equipment should not be allowed by the instructor to enter the

laboratory C-23 and proceed with the experiment.

4.4 Operating Procedure

4.4.1 Operation of portable magnaflux unitAfter preparing for the experiment as mentioned in section 4.2, follow thesesteps to operate and perform experiment with the magnaflux unit:

1. Turn the current control knob to position that gives the desired outputcurrent. This will turn ON the magnaflux unit and red pilot light

labeled as “LINE” will illuminate. Start with a low output current andset the current control knob at 5

2.

Place and firmly hold the prods at right angle against the test

specimen surface. Place prods tips about 6 inches apart, on either side

of line of suspected defect. If the test specimen is smaller than 6inches in dimension, then the distance between two prods can bereduced. and observe the 2 minutes “ON” and 2 minutes “OFF” duty

cycle to prevent overheating. Press and hold prod control switch (seefigure 3) to complete the magnetizing circuit and output amperage

will be displayed on the ammeter display

3. While the test specimen is being magnetized, blow the magnaflux dry powder on the test specimen (second user can do that) gently and

lightly. Watch for the indications to form (see figure 13)



19

Figure 13: Formation of indications of defects on test specimen

surface

4. Blow off the excess magnaflux dry powder to make the defectindications more prominent. Keep the current flowing through the test

specimen while blowing off the excess dry powder



20

Figure 14: Defects indications on test specimen after blowing off

the excess dry powder

5. Stop the current flow and look for indications formed on testspecimen surface

6.

Put back the magnaflux dry powder collected on piece of paper back

in the magnaflux dry powder can/container

Note: Be sure to observe the following while carrying out the operation/testwith the magnaflux unit



21

a) Press prods firmly against the test specimen surface to preventarcing

b) Overlap the areas to be inspected (For weld inspection)c)

Reduce the field strength by adjusting the current control knob

(increasing the output current amperage) or by increasing thedistance between prods, if magnaflux dry powder particles

accumulate excessively at prod pointsd)

Increase the magnetic field strength if there is not some

noticeable influence of the particles at the prods tips (Fieldstrength can be increased by increasing the output current or

reducing the distance between prods)Please refer to Appendix “A” (Operator - inspector guidancecharts - Section III, How magnaflux works) to see the detailed

procedure on weld inspection, large areas inspection and test

specimen inspection using longitudinal magnetization (Cablecoils)

7. Demagnetize the test specimen before shutting down the magnafluxunit. Use A.C. current to demagnetize the test specimen. Please refer

to Appendix “A” (Operator - inspector guidance charts - Section III,How magnaflux works) to see the detailed demagnetization

procedure.

Note: Wear safety glasses and safety gloves while doing the test with

portable magnaflux unit



22

Figure 15: Surface and subsurface defects indicated by magnetic

particle inspection

4.4.2 Shutdown

Normal ShutdownDo the following to shut down the apparatus:

1. Use the field indicator (see figure 5) to check whether the test

specimen is completely demagnetized. Place the field indicator near

the inspected test specimen and see if there is any fluctuations in the



23

field indicator hand. The test specimen is completely demagnetized Ifthe field indicator hand stays at zero

2.

After ensuring no field strength around the test specimen, turn the

current control knob to “OFF” position to shutdown the magnafluxunit. Red pilot light labeled as “LINE” will turn off indicating unit is

turned OFF

3. Unplug the power cable of magnaflux unit

4. Unplug all the cables from output terminals of front panel (15 feet 4/0 prods cables and prod control cable)

5. Clean the test specimen surface of any dry powder by a cloth or

cleaner if available

For emergency shutdown, do not check field strength indications around the

test specimen using field indicator instead proceed with the 2nd

step of

normal shutdown procedure.



24

Figure 15: Test specimen surface cleaned after test

5.0 Inspection and Maintenance

Inspections at regular intervals will be performed on the apparatus to ensure

that it is kept in a safe and well maintained condition. The inspection and

maintenance includes

•

The wiring connection of power cable should be checked for tightness

and that the wire insulation of 15 feet 4/0 prods cables is not cut orfrayed



25

• Ensure that the flawed test specimen is placed in safe casing

(corrosion free environment) to maintain the flawed test specimen

surface in inspection condition

5.1 Periodic & Operational Inspections

Visual inspections are the responsibility of the person who is conducting

experiments on a regular basis with the portable magnaflux unit and should be carried out every time before operating the apparatus. A complete

periodic inspection of the apparatus shall be performed by the person who isconducting experiments on a regular basis with this apparatus but will alert

the faculty in charge in case of any deficiencies in the apparatus. Thedeficiencies such as those listed below shall be examined during both the

periodic & operational inspection and the faculty in charge will determine ifthe deficiencies will affect the safe operation of the apparatus.

a. Damaged or out of order front panel ammeter b.

Frayed or cut wire insulation of 15 feet 4/0 prods cables

c. Worn or damaged output terminals on front paneld.

Warning labels and indicators



26

Figure 16: Warning labels and indicators

6.0 Typical TestsThe actual test procedure will be outlined in the lab script as issued by the professor. A typical test includes detecting the surface and subsurface

defects in the flawed test specimen and understand the magnetic particleinspection method.



27

Appendix ‘A’



Appendix ‘B’

Magnaflux Unit

Documents

Transcript of Magnaflux Unit