Liquid Penetrating Test Industrial Metallurgy.pptx

This PPT is about Liquid Penetrating Test. This test is conducted on metal surfaces to find spots or crack on the surface of the metal.

1. Liquid Penetrant Testing (LPT)

2. Introduction: LPT is also known as Dye Penetrant Testing (DPT) Detecting the Surface Flaws (Cracks, Porosity, etc..) Material: All Materials (Non – absorbent ) except Powder Metallurgy Component Principle: Capillary action Liquid used: Cleaner, Dye and Developer Standard: ASTM E 165 - 02 ASME BP&VC Section V - Article 6

3. Basic Steps Involved in LPT: 1.Cleaning 2.Application of Dye 3. Dwell time 4. Removal of Excess Dye 5. Application of Developer 6. Flaw detection

4. Basic Requirements for LPT: Cleaner Penetrant Developer Light Source

5. Cleaner: Detergent Solvent Alkaline 2. Penetrant : 1. Water Washable 2. Post – Emulsifiable , Lipophilic 3. Post – Emulsifiable , Hydrophilic 4. solvent Removable Based on Washability

6. 3. Developer Dry Powder Water Soluble Water Suspendable Non - Aqueous 4. Light Source: UV Light (Black) Wave Length : 280 - 320 nm

7. Properties of good Penetrant : Penetrant should be drawn into flaws by Capilary action It should easily spread over the surface of the material Penetrant should remain in the flaw and easily remove from the surface of the material It should be fluid Visible under normal and UV Light It should not harmful to Inspector as well as Material

8. Penetrant : Basic types of penetrant : Type 1 - Fluorescent Penetrant : they contain a dye or several dyes that fluoresce when exposed to ultraviolet radiation Type 2 – Visible Penetrants : they contain a red dye that provides high contrast against the white developer background.

9. Classification of Penetrant based on removal process: Method A - Water Washable Method B - Post – Emulsifiable , Lipophilic Method C - Solvent Removable Method D - Post – Emulsifiable , Hydrophilic

10. Method A - Water Washable Can be removed by rinsing with water. Penetrants contain an Emulsifying agent (detergent) It is referred as self – emulsifying penetrant system

11. 2. Method B - Post – Emulsifiable , Lipophilic Oil soluble Interact with the oil based emulsifier to make removal possible

12. 3. Method C - Solvent Removable It requires use of a solvent to remove the penetrant from surface of the component.

13. 4. Method D - Post – Emulsifiable , Hydrophilic They use an emulsifier that is a water soluble detergent . Excess dye is removed with use of water wash.

14. EMULSIFIERS: Method B, lipophilic emulsifiers

15. EMULSIFIERS: Method D, hydrophilic emulsifiers

16. Classification of Penetrant based on detectability or sensitivity: Level ½ : Ultra Low Sensitivity Level 1 : Low Sensitivity Level 2 : Medium Sensitivity Level3: High Sensitivity Level 4 : Ultra High Sensitivity

17. Developer: The role of the developer is to pull the trapped penetrant material out of defects and spread it out on the surface of the part Visible penetrants create a white background so there is a greater degree of contrast between the indication and surrounding background. Developers used with fluorescent penetrants both reflect and refract the incident UV Developers are Chalk powder (dry or dissolved in water )

18. Classification based on method that the developer is applied. Form A - Dry Powder Form B - Water Soluble Form C - Water Suspendable Form D - Non-aqueous Type 1 Fluorescent Dye Form E - Non-aqueous Type 2 Visible Dye Form F - Special Applications

19. Dry Powder Least sensitive and inexpensive Easy to apply Dry powders are white colour . Water Soluble Developer consist of a group of chemical that are dissolved in water. Spray method , dipping , pouring and brusing method can be used. Dryer is used to dry the water at the temperature of 21 o C Water Suspendable It consist of insoluble developer particle suspended in water. Frequent stirring or agitation is required.

20. Non-aqueous Suspend the developer in volatile solvent Applied by spray gun Penetrants pullout from the indication by solvent action Special Applications Plastic or lacquer are special developer s It is used for permanent record.

21. PROCEDURE: Cleaning Surface should be free from contamination like oil, grease, water, paint, plating and heavy oxides particles. Either Mechanical or chemical method Mechanical – Brushing, Machining and Blasting Chemical – Solvent, Alkaline and Ultrasonic cleaning

22. APPLICATION OF DYE: The dye is applied uniformly to the surface of the part and allowed for some time = Dwell time (5 – 60 mins ). applied by spraying, brushing, or dipping Selection of a dye - sensitivity required, materials cost, number of parts, size of area requiring inspection, and portability.

23. Removal of Excess Penetrant :

24. DEVELOPING: A developer is applied to pull the trapped penetrant out the defect and spread it on the surface The dye coming to the surface by reverse capillary action Red visible or Fluorescent indication on a white back

25. INTERPRETATION Visible Penetrants = Normal light (1000 lux ) Fluorescent Penetrants = UV light (320nm – 400nm)

26. ACCEPTANCE CRITERIA (ASME BPVC Section VIII Indications greater than 1.6mm considered as relevant. All linear indications are unacceptable. (Length of the indication is more than 3 times of width of the indication) Rounded indications with max dimension in any one side more than 4.8 mm are unacceptable. 4. Two indications placed apart with in 1.6mm are unacceptable. 5. More than 10 indications in a 6 in2 area are unacceptable

27. APPLICATIONS: Deeper flaws than shallow flaws Small round defects Flaws with a narrow opening at the surface Flaws on smooth surfaces Flaws under tensile loading

28. ADVANTAGES • Can detect surface defects better than VT. • Can inspect parts with irregular shapes easily. • Fast method of inspection and indications are visible directly on the specimen surface. • Considered low cost compared to many other NDT methods . • Is a very portable inspection method.

29. LIMITATIONS : Qualitative Results • Can not detect subsurface and internal flaws • Cannot inspect powder metallurgy components • Precleaning is required for better flaw detectability . •