Process And Application Of Fluorescent Liquid Penetrant Inspections And Preventive Maintenance 3-1-1

Front 1

Successful detection of discontinuities depends on

Back 1

The part being clean enough to allow Penetrant to enter and exit discontinuities

Front 2

Factors used to select most suitable method of cleaning

Back 2

A) type of soil or contaminants to be removed

B) type of material inspected

C) surface condition of part

D) geometry and accessibility of part surface

E) required degree of cleanliness

F) availability and adequacy of cleaning facilities

Front 3

Light oils and soft films (contaminants)

Back 3

1. Oils and light greases

2. Easily removed by solvents

3. Enter surface opening preventing Penetrant from entering

4. May fluoresce under black light

Front 4

Heavy oils and solid Films (contaminants)

Back 4

A) corrosion preventive compound, thick grease, graphite

B) harder to remove; solvent or chemical plus considerable mechanical action

C) same effect as light oils

Front 5

Carbon, varnish, and other tightly held Soils (contaminants)

Back 5

A) partially burned combustible

B) difficult to remove

C) blocks discontinuities and absorbs penetrants

Front 6

Scales, oxides, and corrosion products (contaminants)

Back 6

A) scales and oxides result from exposure to high temperatures

B) very hard to remove

C) stress corrosion often occurs within discontinuities

D) interferes with Penetrant mechanics

E) keeps excess Penetrant on the surface

Front 7

Cleaning processes

Back 7

1. Success of Penetrant Inspections depend on parts being free of contaminants and Soils that could interfere with process

2. No special method is exclusively for preparing parts for Penetrant inspection

Front 8

Pre-testing purpose

Back 8

1. Purpose is to ensure that parts will not be damaged by Penetrant

2. All nonmetallic parts not inspected previously or not having approved technical order SHALL be pre-tested

Front 9

Pre-testing procedures

Back 9

A) Test 100% of spare material, if available. If not available, test small area of part that can tolerate possible damage

B) clean and visually examine the part

C) apply Penetrant; allow to dwell twice as long as normal; wipe excess Penetrant from area and examine for surface damage

D) repeat previous step, using remover and developer and reinspect for damage

E) if any evidence of damage is noted, DO NOT use method

Hint 9

Note: part should be watched when put back into service

Front 10

3 Penetrant Types

Back 10

Type 1 - Fluorescent Penetrant

Type 2 - Visible Penetrant

Type 3 - Visible and Fluorescent Penetrant

Front 11

Properties of Type 1 (Fluorescent)

Back 11

A) magnifies flaw 1000x

B) only type authorized for aircraft use

C) requires black light

Front 12

Properties of Type 2 (visible)

Back 12

A) Magnifies flaw 10x

B) desensitizes type 1

Front 13

Properties of Type 3

Back 13

A) this dual mode combines both properties but they are compromised when compared to individual use

Front 14

3 Classifications of Penetrant materials and process references

Back 14

A) Inspection, Liquid Penetrant. ASTM-E1417 (series)

B) Materials Specifications. SAE AMS 2644 (series)

C) Qualified Products List. QPL-AMS2644-3

Front 15

What does ASTM-E1417 tell you?

Back 15

How to do a penetration inspection

Front 16

What does SAE AMS 2644 tell you?

Back 16

What your materials must be able to do

Front 17

What does QPL AMS 2644-4

Back 17

Where to get materials and what materials you can get

Front 18

Penetrant System

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A) Penetrant and emulsifier are a system and cannot be interchanged

B) developer and solvent removers must be from the same manufacturer. Can be different from Penetrant and emulsifier

Front 19

Characteristics of Penetrants

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1) capable of entering and filling surface openings, however small

2) must remain in opening during removal of excess Penetrant

3) must bleed from opening after excess is removed

4) must present a readily noticeable indication of openings

Front 20

6 specific physical properties and principals of Penetrants

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1) Viscosity

2) Specific Gravity

3) Flash Point

4) Volatility

5) Thermal Stability

6) Storage Temp Stability

Front 21

Principals of Viscosity

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1. Measure of a liquid's resistance to a change in physical shape

2. Decreases as temperatures rise, increases with lower temperatures

3. Determines how much Penetrant remains on surface during dwell, high viscosity clings; low viscosity runs

Front 22

Principals of Specific Gravity

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1) Ratio between densities of a substance to the density of distilled water at 60 degrees F

2) Most commercial penetrants have a specific gravity of less than one

Front 23

Principals of Flash Point

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1) Temperature at which flammable vapors are given off a liquid to form an explosive mixture in air.

2) MILSPEC minimum flash point is 200 degrees F

Front 24

Principals of Volatility

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1) vapor pressure or boiling point of liquid

2) associated with evaporation rate of liquids

3) low Volatility desired

4) Lower Volatility equals higher viscosity

Front 25

Principals of Thermal Stability

Back 25

Heat Fade

Front 26

3 physical principals that allow Penetrant to work

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1) surface tension

2) wetting ability

3) capillary action

Front 27

8 specific Chemical Properties of Penetrants

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1) Chemical Inertness

2) Toxicity

3) Solvent Ability

4) Removability

5) Water Tolerance

6) Mechanism of Fluorescence

7) Brightness

8) Ultraviolet Stability

Front 28

What is Chemical Inertness?

Back 28

Penetrant should not react with materials being inspected

Front 29

What is Toxicity?

Back 29

Measure of adverse effects on humans

Front 30

What is Solvent Ability?

Back 30

Noticeability of Fluorescent dye in oil

Front 31

What is Removability?

Back 31

Removability of excess Penetrant with little or no residual background

Front 32

What is Water Tolerance?

Back 32

Since water contamination is inevitable, method A penetrants have the ability to handle up to 5% water per volume. Methods B and D are not affected by the amount of water.

Front 33

What is Mechanism of Fluorescence?

Back 33

Atomic structure of Fluorescent material and energy level of radiation source

Front 34

What is brightness?

Back 34

Amount of visible light given off when exposed to a black light

Front 35

What is Ultraviolet Stability?

Back 35

Resistance of the dye to lose its ability to fluoresce

Front 36

What are the 3 Penetrant application methods?

Back 36

1) Immersion

a) preferred method when entire part. must be inspected

b) avoid air bubbles and pockets

2) Spraying

a) air or pressure Spraying equipment

b) Electrostatic Spray (automated lines)

c) aerosol spray

3) Brush or Swab (useful for small areas)

Front 37

3 Application Factors

Back 37

1) Penetrant Sensitivity

2) Temperature Limitations

3) Penetrant Dwell

Front 38

What is Penetrant Sensitivity?

Back 38

A) ability to show indications of very small typed cracks

B) use the lowest sensitivity that will reveal the flaw

Front 39

What are the application Temperature Limitations?

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A) Operating range is 40 - 125 degrees F

B) Penetrant inspection SHALL NOT be performed at less than 40 degrees F

C) Sensitivity improves between 125 - 150 degrees F

D) penetrant inspection SHALL NOT be performed above 125 degrees F unless special high temperature Penetrant is used

Front 40

What is Penetrant Dwell?

Back 40

Total length of time from initial application of Penetrant to removal

It allows Penetrant to seep into and fill surface openings

Front 41

6 factors that influence dwell time

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1) width and depth of void

2) type of Penetrant

3) part material and form

4) type of discontinuity

5) penetrant viscosity

6) cleanliness of part

Front 42

What are the 2 basic dwell modes?

Back 42

1) Immersion Dwell - part stays submerged entire time

2) Drain Dwell - part is covered with Penetrant and placed on a rack to dwell

Front 43

What are the minimum dwell times?

Back 43

1) minimum dwell times are based at 60 - 125 degrees F

2) Service induced defects SHALL NOT be less than 30min

3) Shall be doubled for service induced defects if between 40 - 60 degrees F

4) If stress corrosion is suspected, SHALL NOT be less than 240min

Front 44

Effects of under dwell

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1) Penetrant is not allowed to completely fill discontinuities

2) Visibility of results are reduced

Front 45

Effects of over dwell

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1) Results in Residual background Fluorescence

2) causes removal difficulties with older penetrants

3) apply fresh Penetrant every 60min when long dwell times are required

4) when dwell time of 45min or more is involved, apply fresh Penetrant 15min before removal or at any time the Penetrant appears to be drying

Front 46

What Factors influence Penetrant Removal?

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1) Surface Condition

2) Shape and Geometry

3) Flaw Size and Shape

Front 47

How does Surface Condition effect Removability?

Back 47

1) smooth polished surfaces clean easily with any method

2) rougher surface removal is harder; rough surfaces reduce Removability in two ways:

A) restricts mechanical forces of spray rinse

B) prevents emulsifier from evenly combining with Penetrant on surface

Front 48

How does Shape and Geometry effect Removability?

Back 48

1) accessibility of surface to spray

2) thickness of penetrant layers

Front 49

How does Flaw Size and Shape effect Removability?

Back 49

1) Narrow, deep flaws, hold lots of Penetrant, narrow openings restrict diffusion rate of emulsifiers and the mechanical force of a spray

2) removal of penetrant in narrow, shallow flaws will reduce visibility of indications

3) broad, shallow flaws present most critical problems extreme care must be used during penetrant removal

Front 50

4 Methods of Removal

Back 50

Method A - water-washable penetrant removal

Method B - Lipophilic Process

Method C - Solvent Removal Process

Method D - Hydrophilic Remover Process