STANDARD OPERATING PROCEDURE AND SAFETY
GUIDE FOR MAGNANFLUX UNIT
(Located in Rm. C-23 Head Hall)
Prepared
July 28, 2010
Table of Contents
1. Scope ........................................................................................................................................4
1.1 Objective ............................................................................................................................4
1.2 Regulations ........................................................................................................................4
2.Apparatus Overview and objective ...........................................................................................4
2.1 Apparatus overview ...........................................................................................................4
3. Hazards and control evaluation ..............................................................................................13
3.1 Possible fire event ............................................................................................................13
3.2 Ventilation........................................................................................................................13
3.3 Kinetic, thermal & accoustic............................................................................................13
3.4 Electrical ..........................................................................................................................13
3.5 General, physical & equipment concerns ........................................................................14
3.6 Access ..............................................................................................................................15
3.7 Training ............................................................................................................................15
3.8 Personal protective equipment .........................................................................................16
4. Operation................................................................................................................................16
4.1 Qualified personnel ..........................................................................................................16
4.2 Experiment preparation ....................................................................................................16
4.3 Lab instructions ................................................................................................................17
4.4 Operating procedure.........................................................................................................18
5. Inspection and maintenance ...................................................................................................24
5.1 Operational & Periodic inspections .................................................................................25
6. Typical test .............................................................................................................................26
Appendix A: Operator - inspector guidance charts - Section III ...............................................27
Appendix B: Operating manual for P- 90 ..................................................................................28
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C-23, Head Hall floor plan
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1. Scope
1.1 Objective
This standard operating procedure is intended to provide operating
instructions and safety information for the Department of Mechanical
Engineering’ portable magnaflux unit located in C-23, Head Hall. This
document 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 primarily
concerned 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 Environmental
Health and Safety Office of the University of New Brunswick.
2. Apparatus Overview and Objective
2.1 Apparatus overview
The magnaflux unit is an extremely compact integral unit of all aluminum
construction. 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 coil
for 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 of
magnetizing current through the prods. On pressing the switch magnetizing
current flows through the prods, magnetizing the test specimen and releasing
the switch stops the magnetizing current flow through the prods. The control
switch is connected to the control cable outlet of power controller unit via
prod control cable.
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Figure 1: power controller unit controls and output terminals
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Figure 2: Apparatus magnetizing prods and test specimen
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Figure 3: Prod control switch
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Figure 4: Power controller unit front panel
The test specimen is magnetized by firmly holding the two prods to its
surface. 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 in
different 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 the
test specimen.
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Figure 5: Magnaflux dry powder blower and field indicator
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Figure 6: Magnaflux portable unit components overview
The portable magnaflux unit is electrically powered and its power controller
unit 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 finding
defects as early as possible in manufacture, to avoid wasting machining and
processing time on defective material. The operator may use dry or wet
method to do the magnetic particle inspection of test specimen using
magnaflux unit and we only use dry method to carry out this experiment.
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Figure 7: Magnaflux unit main power supply
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Figure 8: Circular magnetization of test specimen
Figure 9: Longitudinal magnetization of test specimen
Please refer to Appendix “A” (Operator - inspector guidance charts - Section
III, 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.
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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 alone
and 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 aid
kit.
3.2 Ventilation
There 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 a
requirement for the operation of magnaflux unit.
3.3 Kinetic, Thermal and Acoustic
There 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 test
specimen. The prods must be held firmly at 90 degrees against the test
specimen surface to prevent arcing and the user should wear safety glasses
while doing the test with magnaflux unit. The magnetizing cables carry high
amperage 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 Electrical
The magnaflux unit is electrically powered and it does not pose any
electrical threat to the user, if handled carefully. Do not, however come into
contact with bare copper prods when they are energized. Make sure all other
lab occupants are clear off the test area before the prods are energized.
Always check the apparatus for bare, frayed or cut electrical cables before
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operating it. Please see figure 7 to see the main electrical outlet powering the
apparatus.
3.5 General, physical and equipment concerns
Hold the two prods parallel to the crack when magnetizing the test specimen
circularly 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)
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While magnetizing the test specimen, apply/dust the dry powder gently and
lightly 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 test
specimen to prevent arcing. The magnetic field strength can be increased or
decreased by adjusting the current control knob to vary the current flow
through 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 but
only 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’s
eye and safety gloves prevent the user from getting any serious burns since
the 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 at
rated 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 or
teacher assistant). No person other than the faculty in charge or specifically
authorized personal are permitted to make alterations to, or run experiments
with the portable magnaflux unit.
3.7 Training
All individuals using the portable magnaflux unit shall be required to receive
training in the proper operation and maintenance of the apparatus and its
controls. Training will include such topics as the complete operation and
controls of the magnaflux unit. Training programs shall be administered by
qualified personnel at UNB.
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3.8 Personal Protective Equipment
Following personal protective equipment is mandatory while using portable
magnaflux unit:
1. Safety glasses
2. Safety gloves
4. Operation
4.1 Qualified Personal
These notes in the operation section will provide a guideline to the
individual 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 to
operate 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 (see
figure 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 (small
magnetic particles)
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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 Responsibilities
The SOP of portable magnaflux unit should be read and understood. This
document provides all the necessary information regarding the apparatus
operation, hazards involved & safety precautions to be taken while using
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apparatus. The lab instructor shall remain in the room while the experiment
is in progress. After the full students group has assembled and before any
explanation has begun the instructor should relay all safety precautions and
hazards 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 unit
After preparing for the experiment as mentioned in section 4.2, follow these
steps to operate and perform experiment with the magnaflux unit:
1. Turn the current control knob to position that gives the desired output
current. This will turn ON the magnaflux unit and red pilot light
labeled as “LINE” will illuminate. Start with a low output current and
set 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 6
inches in dimension, then the distance between two prods can be
reduced. and observe the 2 minutes “ON” and 2 minutes “OFF” duty
cycle to prevent overheating. Press and hold prod control switch (see
figure 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)
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Figure 13: Formation of indications of defects on test specimen
surface
4. Blow off the excess magnaflux dry powder to make the defect
indications more prominent. Keep the current flowing through the test
specimen while blowing off the excess dry powder
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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 test
specimen 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/test
with the magnaflux unit
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a) Press prods firmly against the test specimen surface to prevent
arcing
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 the
distance between prods, if magnaflux dry powder particles
accumulate excessively at prod points
d) Increase the magnetic field strength if there is not some
noticeable influence of the particles at the prods tips (Field
strength can be increased by increasing the output current or
reducing the distance between prods)
Please refer to Appendix “A” (Operator - inspector guidance
charts - Section III, How magnaflux works) to see the detailed
procedure on weld inspection, large areas inspection and test
specimen inspection using longitudinal magnetization (Cable
coils)
7. Demagnetize the test specimen before shutting down the magnaflux
unit. 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
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Figure 15: Surface and subsurface defects indicated by magnetic
particle inspection
4.4.2 Shutdown
Normal Shutdown
Do 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
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field indicator hand. The test specimen is completely demagnetized If
the 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 magnaflux
unit. 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.
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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 or
frayed
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• 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 is
conducting experiments on a regular basis with this apparatus but will alert
the faculty in charge in case of any deficiencies in the apparatus. The
deficiencies such as those listed below shall be examined during both the
periodic & operational inspection and the faculty in charge will determine if
the deficiencies will affect the safe operation of the apparatus.
a.
b.
c.
d.
Damaged or out of order front panel ammeter
Frayed or cut wire insulation of 15 feet 4/0 prods cables
Worn or damaged output terminals on front panel
Warning labels and indicators
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Figure 16: Warning labels and indicators
6.0 Typical Tests
The 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 particle
inspection method.
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Appendix ‘A’
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Appendix ‘B’
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