1. LIQUID PENETRATING TEST
MSM OEP
LIQUID PENETRATING TEST

2. Liquid penetrant testing (PT)
This is a method which can be employed for the detection of open-to-surface discontinuities
in any industrial product which is made from a non- porous material. This method is widely used
for testing of non-magnetic materials. In this method a liquid penetrant is applied to the surface of
the product for a certain predetermined time, after which the excess penetrant is removed from
the surface. The surface is then dried and a developer is applied to it. The penetrant which
remains in the discontinuity is absorbed by the developer to indicate the presence as well as the
location, size and nature of the discontinuity. The process is illustrated in Figure 1.2.

3. Penetrants used are either visible dye penetrant or fluorescent dye penetrant. The inspection
for the presence of visible dye indications is made under white light while inspection of presence
of indications by fluorescent dye penetrant is made under ultraviolet (or black) light under
darkened conditions. The liquid penetrant processes are further sub-divided according to the
method of washing of the specimen. The penetrants can be: (i) water-washable, (ii) postemulsifiable,
i.e. an emulsifier is added to the excess penetrant on surface of the specimen to
make it water-washable, and (iii) solvent removable,

4. Liquid penetrant processes
Post emulsifiable fluorescent dye penetrant.
Solvent removable fluorescent dye penetrant.
Water washable fluorescent dye penetrant.
Post emulsifiable visible dye penetrant.
Solvent removable visible dye penetrant.
Water washable visible dye penetrant.

5. Advantages of liquid penetrant testing
Relatively low cost.
Highly portable NDT method.
Highly sensitive to fine, tight discontinuities.
Fairly simple method.
Can be used on a variety of materials.
All surface discontinuities are detected in one operation, regardless of orientation.

8. Figure 1.2: Different stages of liquid penetrant process.

9. Limitations of liquid penetrant testing
Test surface must be free of all contaminants (dirt, oil, grease, paint, rust, etc.).
Detects surface discontinuities only.
Cannot be used on porous specimens and is difficult to use on very rough surfaces.
Removal of all penetrant materials, following the test, is often required.
There is no easy method to produce permanent record.

10. PRANJAL PATEL-130410119069 MOHSIN PATHAN -130410119076
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