Liquid Penetrant Testing (ASME BPVC Section V - Article 6, ASTM E-165-02)

1.
LIQUID PENETRANT TESTING
(ASME BPVC Section V – Article 6, ASTM E-165-02)
AIM:
To detect the surface flaws in the given weld samples by using Liquid Penetrant
Testing.
APPARATUS AND MATERIAL REQUIRED:
 Solvent cleaner(FC -711/2)

 Dye penetrant (FC – 911/2)
 Developer (FC- 811/2)
 Lint free cloth
 Welded LPG cylinder
PRINCIPLE:
The Liquid Penetrant testing is based on the principle of reverse capillary action.
The settling down of penetrant into the discontinuities is called capillary action and rising of
penetrant from the discontinuities by the application of developer is known as capillary rise.
PENETRANT MATERIALS:
Penetrants are formulated to possess a number of important characteristics. To perform well,

a penetrant must:
 Spread easily over the surface being inspected.
 Be drawn into surface breaking defects by capillary action or other

mechanisms.
 Remain in the defect but remove easily from the surface of the part.
 Remain fluid through the drying and developing steps so it can be drawn back
to the surface.
 Be highly visible or fluoresce brightly to produce easy to see indications.
 Not be harmful to the inspector or to the material being tested.
PROCEDURE:
Steps for Penetrant Testing
1. Pre-Clean
• Parts must be free of dirt, rust, scale, oil, grease, etc. to perform a reliable inspection.
• The cleaning process must remove contaminants from the surfaces of the part and
defects, and must not plug any of the defects.
• Pre-cleaning is the most important step in the PT process!!!
• Some machining, surface finishing and cleaning operations can cause a thin layer of
metal to smear on the surface and prevent penetrant from entering any flaws that may
be present.
• Etching of the surface prior to inspection is sometimes required.
2. Penetrant Application
• Many methods of application are possible such as: Brushing or Spraying or

Dipping/Immersing
• The penetrant solution must be allowed to “dwell” on the surface of the part to allow
the penetrant time to fill any defects present.
• The dwell time vary according to penetrant type, temperature, material type and
surface finish but 10-15 minutes for precise detection 30 minutes is required.
3. Excess Penetrant Removal
• Solvent Removable - The part is wiped with a clean dry cloth to remove the bulk of
the excess penetrant.
• Then, a cloth lightly dampened with solvent is used to remove any remaining penetrant
on the surface
4. Developer Application
• Nonaqueous developer is applied by a aerosol spray to a thoroughly dried and cooled

part. A thin even coating should be applied.
• The coating should be white but still slightly transparent when performing a visible
dye penetrant inspection, and even thinner when performing a fluorescent penetrant
inspection.
5. Inspect/Evaluate
• In this step the inspector evaluates the penetrant indications against specified
accept/reject criteria and attempts to determine the origin of the indication.
• The indications are judged to be either relevant, non-relevant or false.
• A very important step of evaluation is to document findings on an inspection report
form or other record keeping form.
• This may be supported with drawings or photos of indications, etc.
6. Post-clean
• The final step in the penetrant inspection process is to thoroughly clean the part that
has been tested to remove all penetrant processing materials.
• The residual materials could possibly affect the performance of the part or affect its
visual appeal
ADVANTAGES:
 An easy method to learn.

 Very versatile and can be used to examine metals and non-metals.
 Sensitive to small surface breaking discontinuities.
 Post-emulsifiable systems can detect wide, shallow discontinuities.
 Very good for high volume production.
DISADVANTAGES:
 Pre-cleaning has to be thorough.

 Will not detect discontinuities below the surface.
 Rough surface or surfaces with porosity can produce excessive background,
which will interfere with inspection.
 Fluorescent penetrant in particular is sensitive to contamination, which will
severely affect performance and so extensive plant performance checks may
be required for bulk consumables.
INTERPRETATION:
From the test indication of the weld sample it is found that the sample contain contains
 Porosity
 Lack of fusion
 Lack of side wall fusion
 Cluster porosity
RESULT:
Thus the defect was found in the given welded LPG cylinder by using liquid penetrant
testing.
Cluster porosity
Porosity

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1.

LIQUID PENETRANT TESTING

(ASME BPVC Section V – Article 6, ASTM E-165-02)

APPARATUS AND MATERIAL REQUIRED:

 Solvent cleaner(FC -711/2)

Penetrants are formulated to possess a number of important characteristics. To perform well,

 Spread easily over the surface being inspected.

 Be drawn into surface breaking defects by capillary action or other

Steps for Penetrant Testing

• Many methods of application are possible such as: Brushing or Spraying or

3. Excess Penetrant Removal

• Nonaqueous developer is applied by a aerosol spray to a thoroughly dried and cooled

 An easy method to learn.

 Pre-cleaning has to be thorough.

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