liquid penetrating testing

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 testingbased 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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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 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 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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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.

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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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liquid penetrating testing

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