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8/11/2019 Liquid Penetrating Testing
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Liquid
penetratingtesting
Prepaired by dilip tiwari
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TESTING
Testing is process which helps to indentify
your job is in the form homogeneous or not.
There are two types of testing .
1-destructive testing
2-non destructive testing
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Destructive testing
In destructive testing that given the information
about ( surface, sub surface and internal) of
any job with destroying. Example
tensile test,
fracture test,
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racture test
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Tensile test
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Non destructive test
In this method the given the information about
( surface, sub surface, internal ) of any job
without destroying of job.
There are 13 types of non destructive testing .
But there are 6 method is very popularindustries
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METHOD OF NDT
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Type of non destructive testing
There are six methods are very popular inmodern industries.
1- Visual testing 2- liquid penetrating testing
3-Magantinc particle testing
4-Eddy currents 5- Ultrasonic testing
6- Radiography testing
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Course done by SKILL MART
Liquid penetrating testing
Magnetic particle testing
Ultrasonic testing
Radiography testing
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Purpose of the testing
Increase the quality the product.
Reduced the time
Reduced the cost.
Save the human life
These are all benefits of testing.
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Liquid penetrating test
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Magnetic particle testing
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Radiography testing
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BASIC PRINCIPAL OF
METHOD
Liquid penetrating testing- based on CAPILLARYACTION
Magnetic particle testingbased on MAGNATICLEAKAGE
Ultrasonic testingbased on piezo electric effect
Radiography testingbased on absorption ofradiation
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SURFACETESTING
There are two methods applicable for
dictation of surface discontinuity.
1-Visual testing
2-Liquid penetrating testing
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Visual testing
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Liquid penetrating testing
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SUBSURFACE
DISCONTINUTY
There are two methods applicable for sub
surface discontinuity.
1-Magnetic particle testing
2-Eddy currents
M ti ti l
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Magnetic particle
testing
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Eddy currents
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INTERNAL DISCONTINUTY
There are two methods applicable for internal
discontinuity.
1-Ultrasonic testing
2-Radiography testing
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Ultrasonic testing
Back
wall
echo
defect
Back
wall
echo
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Radiography testing
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CHARACTERSTICS OF NDT
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Use of NDT
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APPLICATIONS OF NDT IN RAW
MATERIALS
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INSPECTION IN SECONDRY
PROCESSING
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INSPECTION IN SERVICE IN
PERIODS
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Liquid
penetratingtesting
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Liquid penetrating testing
Liquid penetrating is part of
ndt. It helps to find out the
surface discontinuity of the
any materials by specialsliquid.
Ad f li id i
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Advantage of liquid penetrating
testing
LPT done all type of materials.
It is very easy to apply.
Less training required.
Economically.
It portables.
There are no electric facility required.
Di d t f li id
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Disadvantage of liquid
penetrating testing
LPT is not done on porous materials.
It will given the information only open the
surface discontinuity.
All materials has highly inflammables.
All materials are toxic.
It is required the electric facility required.
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Application of LPT
We can done the liquid perpetrating testing fordifferent place.
Welding Casting
Forging
Round bar
Rubbers
Plastics
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Procedure of LPT
There are five procedure in LPT. The following
steps are given below.
Surface preparation
Apply the penetrates
Excess removal of penetrating
Apply the developer
Interpretation
Post cleaning
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Video clip of waterwashable method of LPT
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Surface preparation
6-Solvent removal method oil,grease, and gum ( only ferrous materials)
The solvent method has portables. This is
the unique property of this method. 7-Sand blasting.paints, varnish,
and resin
8-Grid blasting.paints, varnish,
and resin Grid blasting is applicable only which
materials has more than hardness 45 HRC.
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Surface preparation
9-Etching corrosion
After etching the job heating is necessary
because the hydrogen gas has reduces the
sensitivity of LPT indication. 10-Manual method-There are two type of
manual method
Wire brushing (this method is prohibited) Grinding..rust particles, spatters
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Blow air
1-Blow air
dust only
This method is very
useful for roughsurface.
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Water washables method
2-Water washables
dust and soil
This method is
applicable only nonferrous materials.
After this method
the surface shouldbe dry.
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Vapour digressing
3-Vapors degreasing oil, grease, and gum
This types ofcontaminates are
water insoluble sovapoure breaks thebond and makesthese contaminantssoluble into the water.
This is most popularin ndt method due toeconomical.
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Ultrasonic testing
If emulsifier method isnot done quickly thenultrasonic method ispreferred.
This method is veryuseful for small andmass quantity ofmaterials.
This method is very
costly. This method is used
in production line.
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Solvent removal method
This method is veryuseful for the ferrousmaterials.
This is portables so it is
used in urban area. In this we use the
solvent like alcohol,organic oils, cleaner,etc.
First we removed theexcess penetrate byhand wipe thenremaining penetrate
remove by solvent.
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Sand blasting
This method is
removing for paints,
varnish, and resin.
The sand blastinggenerally not
recombdate coz it
cover the
discontinuity.
It is used for soft
materials.
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Grid blasting
This method is
remove the paints,
resin, and varnish.
This method is usedonly such type of
materials which has
more than 45 HRC.
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Etching
This method is very
useful for remove the
corrosion.
This is removed byacid.
After using this
method the heating is
necessary coz thehydrogen is leaving
the surface of job
otherwise it will effect
the results.
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Dyes
Dyes is colorful dye.Which apply after thesurface preparation.
There are three type
of dye. Visible dye
Fluorescent dye
Dual dye
The dye are differentcolor like pink, yellowblacks, brown andviolet
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Visible dye
In the visible dye wemakes by someadding some dye.This is calledpenetrates.
The penetrates aredifferent color but pinkcolor are mostsensitive.
The visiblepenetrates generallyin day shift. Theminimum lightintensity required
1000 lux.
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Fluorescent dye
Fluorescent dye is type of pigments whichabsorbed the U.V light and emits the visible
light. This type of dye used in night shift. The fluorescent is working on the basis of light
returns in the darkened area. On the jobsurface the light intensity is 20 lux only.
The minimum U.V light intensity required 1000microwatt/cm2
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Dual dye
This type of dyes iscombination of the visible
dye and fluorescent dye.
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Properties of penetrates
The penetrates have following properties.
The penetrates should have to spread well.
the penetrates should have to essay
remove the job after done LPT. The penetrates should have to no chemical
reaction to the job surface.
The penetrates have to low vaioporastion.
Non toxic
Economic
Method of the penetrates
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Method of the penetrates
apply
There are four method to apply the penetrates
on the job surface.
Dipping method ( 100% of LPT to the job)
Flowing method ( large job but smallinterested area)
Spraying method ( this method is
portables) Brushing method ( used when all method
not possible)
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Excess removal of the
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Excess removal of the
penetrates
After dwell time of the penetrates then we
remoive the penetrates. There are four type of
excess of the penetrates from the surface.
Water soluble method (method A)
Emulsifier method (method B)
Solvent removal method (method C) Post emulsification method (method D)
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Water washable method
In this method the excess removal method is
removed by the water.
The all penetrates is made of oily so it is
always water insoluble's. So this type penetrates have to emulsifier has
the bottles itself. So emulsifier makes them
water soluble.
This method is very useful for rough surface,
keyways, threads, where penetrates are
trapped.
Advantage of water
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Advantage of water
washables
1-Fast economical test process.
2-Good and wide range of defect and rough
surface.
3-Easywash with water
4-Easily adaptable to small parts.
5- Good on rough surface keyways, and
threads. 6-Relatively inexpensive.
7-Idael for automation
Disadvantage of water
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Disadvantage of water
washables
1-Not reliable in finding wide and shallowdiscontinuity.
2-Not as reliable on second and third runningof the parts.
3-Suspectible to over- washing.
4-Water contamination is more destructive tothis penetrates.
5- Required longer penetrates time. 6-affetced more by acid and chromates.
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Solvent removal method
Solvent which cant removed directly with water
can be removed by use of organic solvents. The
solvents used are quite and dries quickly and
without a residue.
Normally the same type of solvent are used for
pre cleaning and removing excess cleaning.
The excess penetrates removal is performed by
wiping the parts surface only one direction with aclean and lint free cloth. The proper producre is to
make a single pass then fold the cloth to expose
the clean cloth.
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Solvent removal method
This will remove the most of the penetrates onthe surface. The remaining tracer are removedby wiping with new cloth or paper lightlywetted with solvent remover.
This process are done quickly using aminimum cleaner if the operation is prolongedor if excessive amount of cleaner used somepenetrates are removed from discontinuity.
Directly the applied the cleaner on jobsurface is prohibited.
Advantage of the solvent
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Advantage of the solvent
removal method
No water required.
No electricity for color contrast penetrates.
Spray can supplies fresh uncontaminated
materials.
Can be re run.
Less susceptible to over wash of penetrates ifused carefully ideal for large items.
Disadvantage of the solvent
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Disadvantage of the solvent
removal method
Not as good as water wash on keyways,
threads and rough surface.
Less sensitive for wide shallow defect.
materials are more costly.
Less production than water wash.
Greater hazards of toxicity. Flammability of cleaners.
Post emulsification
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Post emulsification
penetrates.
Hydrophilic emulsifiers are water based
viscous liquids and contains blends of non
ionic detergents, coupling agents, corrosion,
inhabits and dyes. The hydrophilic emulsifier function by
displacing excess penetrate by detergents
action.
These emulsifier are slow action oily lipophillic
emulsifier. Therefore it is easier control the
cleaning process. Because it is incompatible
with water pre rising prior to application of
Post emulsification
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Post emulsification
penetrates.
Hydrophilic removers are applied by
immersion in an aqueous solution. The
concentration of emersions varies between the
range from 2.5% to 30%. The emulsion times varies from 20 seconds to
5 minutes.
The hydrophilic solution are also applied by
spray or a foam.
The monitor of concentration of solution is
measured by the refractor meter.
Advantage of post
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Advantage of post
emulsification penetrates
Good on wide shallow defect.
Washed well after emulsification.
Short penetration time.
Good production especially on large parts.
Normally not affected by acid and chromates..
Suitable for smooth surface.
Disadvantage of post
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Disadvantage of post
emulsification penetrates
Additional step are required in process for
application of emulsifier.
materials are more costly. Not as good as water wash on keyways,
threads, and rough surface.
Usually need UV systems.
D l
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Developer
Developer are very fine and white powders
applied as dry and with a liquid carrier to a
form a thin uniform coating on the test surface.
There are two unction of each developer. 1- it will gave the basic back ground of your
job thats why the developer increase the
visibility.
2- the developer increase the indication by
capillary action and provides the color
contrast.
D l
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Developer
Developers are either applied wet or dry.
The desired end result is always a uniform,
highly porous, surface layer.
Since the quality control requirements for eachof the developer types is slightly different.
They will be covered individually.
The developer thickness are not more than40 micron other wise it will covered the
small discontinuity.
D l
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Developer
There are generally three type of developer.
Dry developer
Wet developer
Water soluble
Water sensible
Solvent sensible developer
D d l
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Dry developer
The dry developer is in the form of powdered.
It used by dipping and spraying by electro
static gun with 25 psi.
It has very low sensitivity. Generally this method is useful for dry and
rough surface in presence of U.V light.
This will also removed by gently blow air whichhas pressure 25 psi.
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W t d l
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Wet developer
These developers are applied immediatelyafter the final wash.
A uniform coating should be applied by
spraying, flowing or immersing thecomponent.
They should never be applied with a brush.
It has higher sensitivity than dry developer. Care should be taken to avoid a heavy
accumulation of the developer solution in
crevices and recesses
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S l t S d bl
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Solvent Suspendable
When applying a solvent suspendable developer,it is up to the inspector to control the thickness ofthe coating.
Visible penetrate system, the developer
coating must be thick enough to provide awhite contrasting background but not heavyenough to mask indications.
When using a fluorescent penetrate system, a
very light coating should be used. The developer should be applied under white light
and should appear evenly transparent.
De elopment time
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Development time
The time taken by remaining penetrate tocame out from the discontinuity. This is called
the development time.
The development time is depends upon thefollowing factors.
1- size of discontinuity
2- temperature of the job Note= both factor are increased then
development time will also increased.
Procedure of the fluorescent
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LPT.
Surface preparation
Apply the fluorescent
U.V light
Interpretation
Post clean
Fluorescent
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Fluorescent
Fluorescent is pigments which absorbs theU.V light and emits the visible light. Thefluorescent is suspensible pigments that whywhen you will spry on the job surface beforeyou will shake well.
There are generally two colour of fluorescent red,orange and Irish green colour.
Fluorescent penetrates response is maximumwhen exposed to 365nm wave length light.
The fluorescent penetrates are moresensitivity than dye because they have lowerviscosity. can penetrates smaller discontinuityand have excellent visibility.
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Fluorescent
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Fluorescent
Fluorescent penetrates should
never be used on surface which
has been proposed previously with
colour contrast penetrates. 1% of
the visible penetrates stop
completely stop the fluorescent
brightness.
Level of the fluorescent
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Level of the fluorescent
Fluorescent penetrates are designed fordifferent sensitivity level.
Level for casting and rough surface.
Level 1.sensitivity 50m NiCr crackpanel.
Level 2. Sensitivity 40m generalpurpose use.
Level 3.sensitivity 20 to 30 m. Level 4 .sensitivity 10m extremely
critical useThis sensitive determined by nickel andtitanium alloy panel containing very small
cracks on it.
Fluorescent brightness
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Fluorescent brightness
Is the amount of visible light given off when afluorescent dyes is exposed to u v light.
It depends upon on.
The thickness of the penetrates film. The intensity of the U.V light.
Amount of fluorescent dye and itscapability to absorbed U.V light.
The efficiency of the dye in converting thereleased electron to visible light.
Use of penetrates
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Use of penetrates
If there is dirt in crack
there is no room for the
penetrates to entre it andthe process will not work.
The part shall be cleanedto open the discontinuity.
Penetrates application
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Penetrates application
The temperature of the test surface shiold bebetween 10ocand 52oc.
The entire area must be wetted with a layer of
the penetrates and allowed to dwell. The penetrate must not dry during dwell time.
The spraying method is best in all method
allow ell. In immersion method dont allowed in the
penetrates and then drain out the penetrates
container.
Dwell time application
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Dwell time application.
The penetrates is left on the test surface forsufficient time to allow penetration into the
discontinuity opening.
The time involved depends on the viscosity ofthe penetrates, the temperature of the parts
and the tightness of the discontinuity to be
detected.
Wrought product required longer penetration
time than cost product.
The penetration time is known as dwell time.
Dwell time application
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Dwell time application.
The dwell time used generally between 10 and30 minutes.
form Type of flaw Minimum
dwell time
(Aluminum)
Minimum
dwell time
(Magnesium)
Minimu
m dwell
time(steel)
casting Porosity, cold shut 5 5 10
forging laps 10 10 10
All weldments Lack of fusion,
porosity, cracks
10 10 20
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Interpretation of the indication
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Interpretation of the indication
Discontinuity on or near surface are indicatedby retention of the particles patterns.
localized surface irregularities due to
machining marks, grinding marks, weldripples, may produced non relevant or false
indication.
Broad areas of particles accumulations which
might mask indications from discontinuity are
prohibited.
Such area shall be cleaned and reexamined.
Evolution of the indications
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Evolution of the indications
Evolution is process of the severity of thecondition after the discontinuity indicationshave been interrupt.
Evaluation leads to the decision as to whetherthe part must be rejected to be repaired aredirectly accepted for use.
In LPT the discontinuity on size of indications
and not on actual size. The recombdate development time as per
ASME Sec V is from 7 to 30 minutes.
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False indication
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False indication
This type of indication by corner,keyways, threads, yarns, grinding
marks, finger prints, tools marks andimproper cleaning.
False indication not a seriousdiscontinuity so it will accepted in our
specimen. In nondestructive inspection, an
indication that may be interpretederroneously as a Discontinuity
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Relevant indication
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Relevant indication
This type of discontinuity are coming from
true discontinuity. The relevant indication
effect on future usefulness of thespecimen.
There are two type of relevant indication
Round indication
Linear indication
Round indication
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Round indication
This type of indication is length always
smaller than 3 times of the width. Thatindication are called round indication.
Porosity,
blow holes,
pin holes etc.
Linear indication
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Linear indication
This type of indication has length alwaysgreater than the 3 times of the width.
Like undercut,
crack, crater crack,
lack of fusion,
lack of penetration
Seems
Blow holes
These indication found only
when it is open to the surface
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ACCEPTACE CRITERIA OF
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THE LPT
By ASME code the acceptance criteria offollowing.
1- We can not acceptance the linear indication. 2- We accept the single round indication up to
4.8mm.
3- more than tree non relevant indication is notaccepted where there space between less
than 1.6mm.
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