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Surface Method Training Course 1
PT - PROCESSING
Asosiasi Uji Tak Rusak Indonesia
Surface Method Training Course 2
CONTENT
Surface Preparation
Penetrant Application
Removal of Excess Penetrant
Developer Application
Inspection
Post Cleaning
Surface Method Training Course 3
1. SURFACE PREPARATION
PURPOSE
To have a clean and dry test surface
Clean no rust, no scale, no paint, nocorrosion product
Dry no oil, no grease, no water
Because if contaminants are present, it willprevent the penetrant from entering thediscontinuities.
Example of contaminants:Oil, grease, scale, rust, welding flux, acids,waterPaint?Plating?
Surface Method Training Course 4
METHODS OF CLEANING
Mechanical CleaningChemical Cleaning
MECHANICAL CLEANING
To remove rust, scale, paint, dust and etc.
Methods of cleaningWire brushingGrindingPolishingSand blastingUltrasonic cleaning
If we use sand blasting, be careful sandblasting of low hardness material may closediscontinuity
Surface Method Training Course 5
SAND BLASTING
BEFORE AFTER
Soft part
It deforms and close the discontinuity
Surface Method Training Course 6
CHEMICAL CLEANING
To remove grease, oil, etc.
Methods of cleaning:
Detergent cleaningRemove surface soilDetergent may be alkaline or acid and shall be non-corrosiveThorough rinsing and drying required
Vapour degreasingRemove organic contaminants such as oil, greaseUse of solvent vapourChlorinated solvent can be harmful to Ni, Stainless Steel, Ti
Steam cleaningSuitable for large articleRemoves inorganic or organic contaminants
Surface Method Training Course 7
CHEMICAL CLEANING
Solvent cleaningRemove grease and oilTypical solvent: alcohol, acetoneCleaner /remover normally supplied bypenetrant manufacturer
De-scaling solutionRemove oxide film
After the cleaning the part should be dried sothat no water or solvent remains in or over thediscontinuities, as this will hinder entrance ofthe penetrant
Drying can be done by using:Infra-red lampsDrying ovenForce air circulationNormal evaporation
Surface Method Training Course 8
2. PENETRANT APPLICATION
TYPES OF PENETRANT
Non-fluorescent/visible dye penetrant
Fluorescent penetrant
PENETRANT SYSTEMS
Water washable
Post-emulsified
Solvent removed
Surface Method Training Course 9
PENETRANT SYSTEMS
Sometimes referred to water washable andnon water washable penetrants
The only different is emulsifier agents
Water washable
Non-water washable
SolventDye
Emulsifier agents
Solvent
Dye
Surface Method Training Course 10
HOW THEY ARE APPLIED
MethodsDipping (or immersing)SprayingBrushingPouring (flowing)Compressed air spray gun
The way we applied is not very important
The temperature of the test part should be between 160C 520C (600F 1250F) for most of the standards
If out of this range, then the standards say your procedure should be proved well apply
Surface Method Training Course 11
PENETRATION TIME
Definition the period of time during whichthe penetrant is permitted to remain on thespecimen. This is known as penetration timeor dwell time
Application Technique
Soak Time
Dwell Time
Penetration Time
ImmersionPeriod of article is in bath
drainingSoak time
+ dwell time
Others - Time
penetrant remains on article
Dwell time
Surface Method Training Course 12
FACTORS THAT AFFACTING PENETRATION TIME
Types of penetrant used (related to surfacetension () and wetting ability (cos) lesstime for non-water washable)
Specimen wetting ability
Material processes (forged parts required moretime than for casting parts)
Types of discontinuity that we are looking for
Temperature of the part
Surface Method Training Course 13
TEMPERATURES OF THE PART
Normally in standard the penetration timesgiven are minimum recommended times
Example ASME the penetration times arevalid for temperature range 160C 520C
Parts with low or high temperature then thepenetration time indicated in manual(manufactures recommendation) is not validany more
Lower temperature of the part - higher thepenetration time and vise versa
Surface Method Training Course 14
THE GENERAL RECOMMENDED FOR PENETRATION TIME*
*NOTE - use recommended values given bymanufacturer
If we use immersion method, then we do notneed 15 minutes to dip the part inside thetank.
1000C
Surface Method Training Course 15
3. REMOVAL OF EXCESS PENETRANT
It depends on the type of penetrant, namely;
Water washable
Non water washable
Solvent removed
Post emulsifiable process (hydrophilic remover,lipophilic emulsifier)
Surface Method Training Course 16
WATER WASHABLE PENETRANT
How to remove it from the surface of the testpart?
Two ways:
a) Simply apply water with certain pressure.
Normal standard the maximum pressureof water jet is less or equal to 50psi.
Excellent result if P ~ 20psi and apply waterat an angle of 450 max.
Good for rough surface, water temperature160C 430C.
900 450
wrong OK much better
Surface Method Training Course 17
WATER WASHABLE PENETRANT
b) For field application where we do not havepressurised water/large amount of water then wecan use wet towel to remove excess penetrant, andthen use water applicator (no pressure) to removethe residual penetrant
WaterWet towel
Discontinuity
Surface Method Training Course 18
NON WATER WASHABLE PENETRANT
a) POST EMULSIFIED PROCESS
The penetrants employed in the post-emulsified process do not contain an emulsifying agent
The penetrant is not soluble in water
Use emulsifier to render non water washable penetrant to become water washable
Two types of emulsifier:
Lipophilic
hydrophilic
Surface Method Training Course 19
NON WATER WASHABLE PENETRANT
LIPOPHILIC (OIL BASE)is applied by dipping, spraying and NEVER bybrushHow it works?
Apply P.E penetrant (non-water washablepenetrant)
Apply emulsifier before removing the penetrant
Apply emulsification dwell time
Non-water washable penetrant
Non-water washable penetrantEmulsifier
Non-water washable penetrant
Water washable
Surface Method Training Course 20
NON WATER WASHABLE PENETRANT(LIPOPHILIC)
The emulsifier will completely mix with thepenetrant on the surface become water washable
Inside discontinuity it still non-water washable
For fluorescent penetrant washing should bechecked with black light
The amount of time that the emulsifier is permittedto remain prior to the removal process is usually inthe range of 1 to 3 minutes, seldom exceeds 5minutes
The exact emulsification dwell time must bedetermined by experiment
Surface Method Training Course 21
NON WATER WASHABLE PENETRANT
HYDROPHILIC (WATER BASE)REMOVER/EMULSIFIER
Before dipping the part (after penetrantapplication) into detergent tank rinse the partwith water sprayed is preferred
Immerse the part into detergent
Emulsification time or contact time may varyfrom 30 sec. 15 min. depending on sample ordiscontinuity to be inspected
Wash with water
Surface Method Training Course 22
NON WATER WASHABLE PENETRANT( Post Emulsified Process)
THE EMULSIFICATION TIMEIs the most important parameter in P.E processTo short emulsification time;
Emulsifier not completely mix with penetrantDuring washing difficult to remove the penetrant fromthe surface
To long emulsification time;Emulsifier will mix with penetrant inside thediscontinuitiesDuring washing it is possible that the penetrant insidethe discontinuities will also be removed as well reducesensitivity
The best emulsification time can only be determinedon the part itself. The best time is the minimum timethat leaves no excess penetrant on the surface
emulsifier
Non water washable penetrant
Water washable penetrant
Surface Method Training Course 23
NON WATER WASHABLE PENETRANT
b) REMOVED BY SOLVENTUse cloth/paper tissueUse solvent or penetrant removal from thesame penetrant manufacturerMethod
Remove as much excess penetrant as possiblewith dry lint-free clothRemove the remaining excess with removerdampened lint free cloth (clean) until no trace ofpenetrant on clothWhen using visible dye penetrants, checked forcomplete removal by nothing that the lastremover dampened wipe is `colour freeWhen removing fluorescent penetrants, checkprogress with black light and stop when testsurface no longer fluoresces
Never apply (or spray) solvent directly tospecimen, because we also can clean some ofthe penetrant inside the discontinuities
The less solvent we use the better is the result
solvent Less sensitivity
Surface Method Training Course 24
4. DEVELOPER APPLICATION
Sequence
1. Dry developer or non aqueous developer
The part should be dried first before applythe developer
2. Water soluble or water suspendable
The parts have to be dried after applying thedeveloper
Surface Method Training Course 25
WET AQUEOUS DEVELOPER (WATER SOLUBLE)
How it applies?
By dipping the part into tank container (contain developer)
Difficult to get uniform layer of developer
After developer application, the part has to be dried in oven (80oC 100oC)
By pouring or flowing
By using compressed air spray gun
Surface Method Training Course 26
DRY DEVELOPER
By dipping the part into the tank
By using powder applicator or rubber squeeze bulb or low pressure spray gun
NON AQUEOUS DEVELOPER
Spray can or spray gun or electrostatic sprayer
Note never blow air to accelerate solvent evaporation
Surface Method Training Course 27
DEVELOPING TIME
Is the time from developer application to the time part is inspected
Rule of thumb to use a developing time of around half of the penetration time
Example: penetration time : 20 minutesdeveloping time : 10 minutes
10 minutes is 99.9% good because if the indication is not seen after 10 minutes then the part contain no discontinuities
Surface Method Training Course 28
5. INSPECTION
LIGHTING REQUIREMENTS
Good illumination should according to standard
White Light : visible penetrant
350 Lux or 32.5 ft/candles
Black light : fluorescent penetrant
ASME Code 1000watts/cm2 at 38cm from the surface;
MIL-I-25135D - 1200watts/cm2
Surface Method Training Course 29
GENERAL RECOMMENDATION (BLACK LIGHT)
Allow a minimum of 5 minutes to warm thelamps before starting inspection
Stay a minimum of 5 minutes in the darkenedarea before starting inspection
DONT switch ON and OFF the lamp often itwill shortened the life of lamp
Keep the filter inside the lamp clean all thetime
Surface Method Training Course 30
INSPECTION(two Steps)
INITIAL INSPECTIONIs done as soon as possible after applying the developer
Remember we have to write a report
Mainly good for porosityTo know better the type, nature and extend of discontinuities
Need initial inspection
Big porosity
In-line porosity
Four porosity
Immediately after applying
developer
PorosityAfter 1 minute
After 3 minutes
After 10 minutes
Surface Method Training Course 31
INSPECTION(two Steps)
FINAL INSPECTION
Is done when the developing time has elapsed
Wrong interpretation it looks like a big defect
Therefore, initial inspection is required becausenormally porosity has small opening but withbig volume inside
Final inspection
Big porosity
In-line porosity (looks like linear discontinuity)
Four porosity
(looks like big porosity)
Surface Method Training Course 32
6. POST CLEANING
After complete the inspection we have toclean the part (as soon as possible especiallyfor standard sample)
Method (for standard sample)
Best vapour degreasing or ultrasonic cleaning
Apply developer if indication reappear thenthe cleaning procedure should be repeated.
PT - PROCESSINGCONTENT1. SURFACE PREPARATIONMETHODS OF CLEANINGSAND BLASTINGCHEMICAL CLEANINGCHEMICAL CLEANING2. PENETRANT APPLICATIONPENETRANT SYSTEMSHOW THEY ARE APPLIEDPENETRATION TIMEFACTORS THAT AFFACTING PENETRATION TIMETEMPERATURES OF THE PARTTHE GENERAL RECOMMENDED FOR PENETRATION TIME*3. REMOVAL OF EXCESS PENETRANTWATER WASHABLE PENETRANTWATER WASHABLE PENETRANTNON WATER WASHABLE PENETRANTNON WATER WASHABLE PENETRANTNON WATER WASHABLE PENETRANT(LIPOPHILIC)NON WATER WASHABLE PENETRANTNON WATER WASHABLE PENETRANT( Post Emulsified Process)NON WATER WASHABLE PENETRANT4. DEVELOPER APPLICATIONWET AQUEOUS DEVELOPER (WATER SOLUBLE)DRY DEVELOPERDEVELOPING TIME5. INSPECTIONGENERAL RECOMMENDATION (BLACK LIGHT)INSPECTION(two Steps)INSPECTION(two Steps)6. POST CLEANING