EQUIPMENT AND MATERIALS:

This procedure is intended for use with the following consumables or their equivalent.  It has to be ensured that the consumables are selected in such a way that they are compatible to the test surface and object and as per test requirements.

Dye Penetrant Inspection - Water Washable, Fluorescent Penetrant System

Dye Penetrant Inspection - Water Washable, Visible Penetrant System

Ø  Intermixing of penetrant materials from different families (manufacturers) is not permitted by this procedure.

             Manufacturer’s recommendation for compatible penetrant systems must be adhered with.

Ø  Dye Penetrant Inspection - Control of Contaminants                                                       

               When testing nickel based alloys, austenitic stainless steels and titanium, contaminant content of penetrant materials shall be controlled.  Control shall be based on the manufacturers batch certification which shall                                 include, as a minimum, the manufacturer’s name, batch number and chemical contaminant content as determined in accordance with ASME Section V, paragraph T-625. 

Only dye penetrant inspection materials having a batch number printed on the container and traceable to a valid manufacturer’s batch certification on file shall be used.

 PARTS TO BE EXAMINED:

This procedure shall be used for parts or welds in ferrous and non-ferrous materials in accordance with applicable code or specifications for parts or welds.                                  

When welds are tested, at least one inch of the base material on both sides of the weld is to be covered.     

 SURFACE PREPARATION:

Ø  Prior to the test, the area to be inspected and at least one inch on either side shall be free from all contaminants (dirt, grease, lint, slag, spatter, oil, scale, water and protective coatings).

Ø  In general for welds, satisfactory results may be obtained when the surface to be inspected is in as welded condition.If mechanical methods of cleaning like grinding, machining or sanding is necessary, the surface area shall be etched to remove smeared metal. (For full details, ASME Sec. V, article 24 and SE-165 shall be referred). After etching, suitable neutralising solutions shall be used and test surface be washed with water.

Ø  Unless otherwise recommended by the manufacturer, welded components or parts cleaned by Vapour degreasing, organic solvents or detergents, and properly protected from contamination, need not be re-cleaned with penetrant cleaner (remover) prior to application of the penetrant.

On occasion, a wire brush may be helpful in removing rust, surface scale, but it is used only  when no other means of removal will surface.  It shall be followed by cleaning with penetrant cleaner if compatible.

Ø  Dye Penetrant Inspection - Drying:

Evaporation time, following precleaning, shall be 5 minutes minimum.  Where indications of retained moisture exist, the evaporation time shall  be increased till no evidence of moisture in the area of test can be detected.

EXAMINATION:

Ø  Dye Penetrant Inspection - Temperature Limitations: The temperature of the penetrant materials and the surface of the part should be between 50°F and 100°F for fluorescent water washable penetrants and between 60°F and 125°F for visible penetrants.

Ø  Dye Penetrant Inspection - Penetrant Application:

                     a) Either immersion (dipping), flow-on, spray, or brushing technique is used to apply  the penetrant to the precleaned dry specimen.                 

                    b) The penetrant is applied evenly over the entire area.

                   c)  Fillers shall be used on the upstream side of the air inlet when using compressed air to apply penetrant.

Ø  Dye Penetrant Inspection - Dwell times:

                   a) Penetrant dwell times are critical and should be adjusted depending on temperature and other conditions and may require qualification by demonstration for specific applications.

                  b) Typical minimum penetration times are given in the Table-1. 

                 c) Penetrant shall remain on the test surface for the entire dwell time period. 

                 d) Care shall be taken to prevent drying out of the applied penetrant and additional penetrant must be applied to re-wet the surface. 

Dye Penetrant Inspection - Typical Minimum Penetration Times

Ø  Dye Penetrant Inspection - Excess Penetrant Removal:

After the elapse of penetrant dwell time, the excess penetrant is removed by water spray.  Water at 60°F to 110°F and a pressure not exceeding 30 psi (210 KPa) is applied with droplet type sprayer specifically designed for penetrant removal.  The nozzle of sprayer is  held so that water strikes the surface of the specimen at an angle of approximately 45 degrees.  Care is to be taken to avoid over-washing, which causes washout of penetrant from discontinuities. Other methods of referenced codes or specifications could also be used if applicable for the test surface conditions. 

Ø  Dye Penetrant Inspection - Drying:

The test surface must be dry prior to the application of non-aqueous or dry developers.  If water-based wet developer is used, it is applied to still damp specimen immediately after the penetrant removal wash.  Excessive heat or too long a drying time tends to bake the penetrant out of  discontinuities.           

Ø  Dye Penetrant Inspection - Developer Application:

When the drying process is complete, the specimen is ready for the application of either dry or non-aqueous wet developer.  When water-based wet developer is used, it is applied by flooding the surface to the wet specimen immediately after excess penetrant is removed.                                          

It is recommended to use aerosol cans, after agitation, typically for weld inspection at various project-site works.  Spray distance shall be 10” to 12” from test surface.  The test-areas must be cool enough to prevent too repaid evaporation of the developer vehicle.

Dry developer is applied to the specimen by brushing with soft brush, by use of a powder    gun, or by dipping the specimen in a tank of the developer and removing excess powder with a low pressure air flow.

An even thin coat/film of developer is preferred.

Applied developer shall not be removed from test surface.

Ø  Dye Penetrant Inspection:

Ø  The area under inspection shall be observed during application of developer and at intervals during development time.

Ø  The recommended development time is between 7 and 30 minutes.Development time begins directly after application of dry developer and as soon as wet developer coating has dried on parts-surface.

Ø  Indications getting formed and formed at the test surface (by the blotting action of developer) be noticed, analysed (relevant indications be noted) under adequate lighting conditions.                

Ø  Lighting Conditions:

               a) Visible penetrant indications can be examined in either natural or artificial light.  Adequate illumination is required to ensure no loss in the sensitivity of the examination.  A minimum light intensity at the examination                       site of 100 fc (1000 Lx) is recommended.

                 b) Examine fluorescent penetrant indications under black light in a darkened area.  Visible ambient light should not exceed 2 ft candles (20 Lx).  The measurement should be made with a suitable photographic-type               visible light meter on the surface being examined.

Black Light Level Control - Black light intensity, minimum of 1000 µW/cm2, should be measured on the surface being examined, with a suitable black light meter.  The black light wavelength shall be in the range of 320 to 380 nm. 

The intensity shall be checked at least once every 8 hours, or whenever the work station is changed.  Cracked or broken ultraviolet (UV) filters should be replaced immediately.  Defective bulbs, which radiate UV energy, must be replaced before further use.  Since a drop in line voltage can cause decreased black light output with consequent inconsistent performance, a constant-voltage transformer should be used when there is evidence of voltage fluctuation.

Caution: Certain high-intensity black light may emit unacceptable amounts of visible light, which will cause fluorescent indications to disappear.  Care should be taken to use only bulbs certified by the supplier to be suitable for  such examination purposes.

Note: The recommended minimum light intensity is intended for general usage.  For critical examination, higher intensity levels may be required.

Black Light Warm Up - Allow the black light to warm up for a minimum of 10 min prior to its use or measurement of the intensity of the ultraviolet light emitted.

Visual Adaptation - The examiner should be in the darkened area for at least 5 min before examining parts to allow the eyes to adapt to the dark viewing.

Caution - Photochromic lenses shall not be worn during examination.