Non Destructive Test (NDT)– Procedure

 NDE test: - NDE Inspection is used to detect any surface-connected discontinuities such as cracks from fatigue, quenching, and grinding, as well as fractures in joints.











Material required for NDE test:

1)    Penetrant (Red color)

2)    Cleaner

3)    Developer (White color)

Penetrant: Penetrants are classified into two types.

1. Fluorescent 2.Non- Fluorescent.

Fluorescent penetrants contain two or more dyes that fluoresce when excited by ultraviolet (UV-A) radiation.

Non-Fluorescent penetrate inspection is performed in a darkened environment.

NDE test Inspection steps:-

 

1.      PRE-CLEANING

2.      APPLICATION OF PENETRANT

3.      EXCESS PENETRANT REMOVAL

4.      APPLICATION OF DEVELOPER


1.       PRE-CLEANING:- The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale that could either keep penetrant out of a defect, or cause irrelevant or false indications. Cleaning methods may include cleaning solvents.

                                                                


 

2.    APPLICATION OF PENETRANT: - The penetrant is the highly colorful dye usually in bright color like red, etc. The penetrant is normally a less viscous liquid that enables it to penetrate into cracks; moreover it is the capillary action that causes the penetrant to be sucked inside the cracks. (Generally 5 to 60 minutes). .



                                               

 

3.      EXCESS PENETRANT REMOVAL: - The excess penetrant is then removed from the surface. The removal method is controlled by the type of penetrant used. if excess penetrant is not properly removed, once the developer is applied, it may leave a background in the developed area that can mask indications or defects. In addition, this may also produce false indications severely hindering your ability to do a proper inspection.



 

4.      APPLICATION OF DEVELOPER: The developer is basically an absorbent chemical quite similar to chalk powder for its absorption capabilities. The developer sprayed on top of the surface where the penetrant has already been applied to tend to absorb the penetrant present in the cracks and indicates the same clearly to the eye.



 

Advantages and Disadvantages of NDE Test

 

ADVANTAGES:-

  • High sensitivity (small discontinuities can be detected).
  • Few material limitations (metallic and nonmetallic, magnetic and nonmagnetic, and conductive and nonconductive materials may be inspected).
  • Rapid inspection of large areas and volumes.
  • Suitable for parts with complex shapes.
  • Indications are produced directly on the surface of the part and constitute a visual representation of the flaw.
  • Portable kit.
  • Low cost.

DISADVANTAGES:-

  • Only surface cracks can be detected. Any cracks below the surface or sub surface cracks cannot be detected
  • Method works well only for surfaces that are machined or polished. Irregular or very rough surfaces tend to provide false results.

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