Dye Penetrant Testing Procedure

1.0 SCOPE:

This procedure describes the method, technique and acceptance standards for liquid penetrant examination for ferrous and non-ferrous materials and weldments for the detection of discontinuity which are open to the surface as cracks, seams, laps, cold shuts, laminations, isolated porosity in non porous material.

2.0 REFERENCE:

a) ASME SEC. V, Article – 6 & 24

b) ASME SEC.VIII division I & 2

c) ASME/ANSI B31.1 – Power piping

d) ASME/ANSI B31.3 - Process piping

e) ASME Sec VIII Div. 1 & 2

f) AWS D1.1

3.0 PERSONNEL QUALIFICATION

The personnel performing examination shall be certified in accordance for qualification and certification of NDT personnel. SNA-TC-1A 2020

4.0 PENETRANT MATERIALS

4.1 The penetrant test materials include all penetrants solvents or cleaning agents, developers etc., used in the examination process.

4.2 Penetrant shall be of solvent removable type and shall have a contrast color that is visible under normal lighting condition. The penetrant is normally red in color so that the indications produce a definite contrast with white back ground of the developer.

4.3 Non aqueous suspension of developer particles in a volatile solvent carrier shall be used.

4.4 The cleaner used for the surface cleaning shall be an organic chemical such as acetone.

4.5 All liquid penetrant materials used on nickel-based alloys, austenitic stainless steels and titanium shall be analyzed as specified in T 641 of article 6 of ASME Sec V for sulphur content and chlorine plus fluorine content and this shall not exceed 1% each of the residue by weight. The manufacturer shall certify the above requirement for each batch supplied.

4.6 Suppliers, brand names and the penetrant test materials used shall be approved.

5.0 SURFACE CONDITION:

5.0

5.1 The surface to be examined and all adjacent areas within at least one inch shall be dry and free of all dirt, grease, lint, scale, welding flux, spatter, paint, oil and other extraneous matter that could obscure surface openings or otherwise interfere with the examination.

5.2 Surface preparation by grinding, machining or etching shall be carried out when surface irregularities mask the indications of unacceptable discontinuities or otherwise interfere with the effectiveness of examination.

6.0 PROCEDURE:

6.1 Temperature Limits:

6.1.1 The temperature of the penetrant and the surface of the part to be examined shall not be below 5°C (50°F) nor above 52°C (125°F) throughout the examination period.

6.2 Pre-Cleaning:

6.2.1 Prior to the liquid penetrant examination, the surface to be examined and all adjacent areas within at least 1 inch (25mm) including the heat affected zone in the case of weld shall be cleaned. The surface shall be free from any rust, scale, welding flux, spatter, grease, paint, oily films, dirt etc., that might interfere with the penetration.

6.3 Drying After Cleaning:

6.3.1 The area to be examined shall be thoroughly dried by exposure to atmosphere after cleaning. Since any liquid residue will hinder the entrance of the penetrant, drying may be accomplished by warming parts in drying ovens, with infrared lamps, forced hot or cold, air or exposure to ambient temperature. A minimum of 30 seconds shall be allowed for the part to be dried after cleaning.

6.4 Penetrant Application:

6.4.1 The penetrant shall be applied by brushing or spraying. For spraying a hand pump or aerosol spray cans shall be used.

6.4.2 After application, the excess penetrant shall be allowed to drain from the part while allowing for proper penetrant dwell time. The length of time the penetrant shall remain on the part to allow proper penetration shall be as recommended by the penetrant manufacturer and the minimum dwell time shall meet the requirements of Table - I.

6.5 Removal of Excess Penetrant:

6.5

After the required penetration time, the excess penetrant shall be removed in so far as possible by using wipers of a dry, clean, lint-free material, repeating the operation until most traces of penetrant have been removed. Then lightly moisten a lint-free material, with remover solvent and wipe the remaining traces gently to avoid the removal of penetrant from discontinuities, taking care to avoid the use of excess solvent. Flushing the surface with the solvent following the application of the penetrant and prior to developing is prohibited.

6.6 Drying:

After removal of excess penetrant, the surface shall be dried by normal evaporation. Normally no other drying techniques are necessary, so long as the processing temperature range is within the specified temperature range.

6.7 Developer Application:

The developer shall be applied as soon as possible to the area being examined by spraying after the excess penetrant removal and area has been dried. The areas shall be sprayed so as to assure complete coverage with a thin even film of developer. However, the time interval shall not exceed two minutes.

7.0 EVALUATION:

7.1 Inspection shall be made after a minimum period of ten minutes (Refer Table - I) and not later than 60 minutes after the application of developer.

7.2 The evaluation shall be carried out with a minimum light intensity of 100 fc
(1000 Lx) to ensure adequate sensitivity during the examination and evaluation.

7.3 Discontinuities at the surface will be indicated by bleed out of the penetrant, however localized surface irregularities such as from machining marks or other surface conditions may produce false indications.

7.4 An indication is the evidence of a mechanical imperfection. Only indications with major dimensions greater than 1/16” (1.58 mm) shall be considered relevant.

a) A linear indication is one having a length greater than 3 times the width.

b) A rounded indication is one of circular or elliptical shape with the length equal to or less than 3 times the width.

c) Any questionable or doubtful indications shall be reexamined to determine whether or not they are relevant.

8.0 ACCEPTANCE STANDARDS:

Relevant indications exceeding the following value are considered repairable.

8.1 ASME Sec. VIII Div. I

All surfaces to be examined shall be free of:

8.1.1 Relevant linear indications;

8.1.2 Relevant rounded indications greater than 3/16inch (4.8mm);

8.1.3 Four or more relevant rounded indications in a line separated by 1/16 inch
(1.6 mm) or less (edge to edge).

9.0 REPAIR & RETEST:

9.0

Whenever an imperfection is repaired by chipping or grinding and subsequent repair by welding is not required, the excavated area shall be blended into the surrounding surface so as to avoid sharp notches, crevices or corners. Completed repairs shall be reexamined by the method originally used.

10.0 POST CLEANING:

10.1 When the inspection is concluded, materials shall be cleaned by dry cotton waste, leaving the product in a dry and clean condition.

11.0 REPORTING:

11.1 A detailed report in the standard proforma as shown in Attachment No.1, signed by Level II personnel shall be issued.