How to do dye Penetrant testing of welds


    Dye penetrant testing procedure.

    Dye penerant testing(DP) also known as liquid penetrant testing(LPT) Or Penetrant testing(PT).
    So i am giving you procedure for doing DP.
    dye penetrant testing kit(developer,penetrant)

    What is dye penetrant testing?

    Dye penetrant testing or liquid penetrant testing is form of non destructive testing for locating discontinuities in (welding,casting,forging etc) components based on capillarity or capillary action.

    what is capillarity or capillary action?

    "Ability of liquid to flow in narrow spaces without the assistance of or opposition of external forces."

    Main types of Dye penetrant testing

    • visible Dye penetrant testing
    • Fluorescent  DP testing.
    • Dual sensitive penetrants(contain characteristics of both visible and fluorescent dyes.

    Which type discountuinities detected using DP test?

    Only defects open to the surface are located using  dp test.Subsurface defects not detected.

    Defects detected using DP test

    • Cracks
    • Undercuts
    • porosity
    • pinholes
    • blowholes
    • lack of fusion
    • etc

    Principles of penetrant testing

    working principle dye penetrant testing

    Steps in DP test.(dye penetrant test  or Liquid penetrant test)

    STEP 1   PREPARING JOB FOR DP
    Prepare job ready for DP test depend upon manufacturing method used for example. consider welded joint to be examined.

    Do mechanical cleaning like grinding,buffing,wire wheeling etc.
    Grind start end points,high points.
    (Grindermans duty)
    cleaning of job for LPT test

    STEP 2  CLEANING AREA TO TO BE TESTED USING DP

    Clean the job using cotton waste using thinner,detergent,water chemical cleaners etc. Depend on type of penetrant used.
    steps in dye penetrant test


    STEP 3  APPLY DYE PENETRANT

    Apply dye penetrant by means of brushing or spraying.
    Penetrant used have high surface wetting characteristics. 
    how to do dye penetrant testing

    STEP 4 GIVE DWELL TIME

    provide dwell time for dye penetrant to penetrate into defects via capillary action and other mechanisms.

    Dwell Time depends on mfg. process used on component.
    generally
    • Welding 5-7 minutes
    • casting 10-15 minutes.

    STEP 5 REMOVE EXCESS PENTRANT
    Remove excess pentrant using cotton and thinner depend on type of penetrant used (for eg. water washable,thinner washable,detergent washable etc).
    dye penetrant testing procedure

    Points to be noted.
    Don't over-clean or use extra cleaning agents it will remove all penetrant from discontinuity and defects not developed.

    STEP 6 APPLY DEVELOPER OVER SURFACE

    Apply developer after cleaning excess penetrant. 
    Developer pulls excess penetrant traped inside defects back the surface.

    Apply developer spray by keeping it 15cm away from Job.
    liquid penetrant testing step by step


    STEP 7 GIVE DEVELOPING TIME

    Give 2-3 minutes developing time to pull penetrant inside discontinuity back to surface.


    STEP 8 EXAMINE SPECIMEN/SURFACE

    Examine/inspect surface visually for type 1(visual) DP test or using Ultra violate light for fluorescent DP test.
    You can also use binoculars for more clarity for size of defect.
    how to do liquid penetrant test

    STEP 9 POST CLEANING
    after completing dp testing of welding clean it using cotton and cleaner.
    liquid penetrant test,dye penetrant test,penetrant NDT test,DP,LPT,PT

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    dye penetrant testing procedure,pdf for dp test,liquid penetrant testing procedure,how to do dp,how to do penetrant testing,step by step guide dp test
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    1 comments:

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