Dye Penetrant / Liquid Penetrant testing procedure
In this post, I have drafted ready use DPT/ LPT Testing Procedure. You can use it as it is by changing the company names/ written practice procedure number.
1.1 This procedure shall be used for detecting discontinuities in Structural Fabrication of XXXXX that are open to surface such as cracks, lack of fusion. This procedure covers color contrast (visible) liquid penetrant examination method utilizing the solvent removable process. The processes like water washable and post emulsifiable shall not be applicable. When applicable, shall automatically call for procedure revision.
1.2 This procedure will be applicable for Inspection of XXXXX.
1.3 Extent of Liquid Penetrant Inspection examination will be 100% welds of bed plates of all units & welds joining XXXX shall be carried out. (Put item details)
1.4 The extent of examination shall be as per Product Quality Plan.
2. Reference Documents
Applicable edition & addenda of the following:
2.1 AWS D 1.1 Edition 2020.
2.2 SNT-TC-1 A Edition 2021
2.3 DIN EN 571 , along with evaluation to ISO 5817, class 8.
2.4 XXX Written Practice
2.5 Client specification XXX.
3. Personnel Qualification
3.1 Personnel performing Liquid Penetrant Examination shall be qualified in conformance with the current edition of the American Society for Nondestructive Testing Recommended Practice No. SNT-TC-1A and XXXXX Written
Individuals who perform NDT shall be qualified for.
3.1.1 NDT Level II , or
3.1.2 NDT Level I working under the NDT Level II
3.2 Certification of Level I and Level II individuals shall be performed by a Level Ill individual who has been certified by (1) The American Society for Nondestructive Testing, or
(2) has the education, training, experience, and has successfully passed the written examination described in SNT-TC-1A.
3.3 Personnel involved in conducting the test, recording results and evaluating the same against applicable acceptance standards shall be certified to at least Level II as per XXXXX Written Practice.
3.4 In satisfying the requirements of 3.3, the qualification of the PT operator shall include a specific and practical examination which shall be based on the requirements of this code. This examination shall require the PT operator to demonstrate the ability to apply the rules of this code in the accurate detection and disposition of discontinuities.
4. Penetrant Materials
Reagent grade chemicals should be used in all tests.
4.1 The following group of solvent removable penetrant materials are approved for use:
Magnaflux SKL-SP1 – Penetrant
Magnaflux SKC – S- Cleaner
Magnaflux SKD – S2 – Developer
4.2 RESTRICTION: Intermixing of penetrant materials from different groups is not permissible.
4.3 Control of Contaminants:
Batch certificates from manufacturer shall be the basis for acceptance of the penetrant materials. The certificates shall include the penetrant manufacturer’s batch numbers and the test results for sulphur and total halogen content which
shall not exceed values given below.
a) For Nickel Base Alloys only:
Sulphur contents shall be determined as per Mandatory Appendix II and shall not exceed 1% of residue by weight.
b) For Austenitic Stainless Steel and Titanium only:
Halogen content shall be determined as per Mandatory Appendix II for chlorine and Fluorine. The total halogen content shall not exceed 1% by weight.
c) Certification of contaminant content for all liquid penetrant materials in line with above requirements is required. Certification shall include penetrant manufacturer’s Batch no and test results.
5. Surface Preparation
5.1. In general as welded, surfaces are accepted .The surface to be examined and all adjacent areas within at least 25 mm (1″) shall be dry and free of all dirt, grease, lint, scale, welding flux, weld spatter, paint, oil and other extraneous matter or processing residuals that could obscure surface openings or otherwise interfere with the examination.
5.2. This could be achieved by using cleaning solvents, vapor degreasing or chemical removing processes.
5.3. Surface conditioning by grinding, machining, polishing or etching shall be performed to remove the peened skin or process residuals when penetrant entrapment in surface irregularities might mask the indications of unacceptable discontinuities or otherwise interfere with the effectiveness of the examination.
6.1. All parts or areas of parts to be inspected must be cleaned and dried before the penetrant is applied .Inspection area must be free of rust, scale, welding flux, weld spatter, grease, paint, oily films, dirt, and so forth, that might interfere with the penetrant process.
6.2. The area under examination shall be cleaned with the cleaner from the group of penetrant materials selected in accordance with paragraph 5.1 Cleaning shall be accomplished by spraying and wiping with lint free cloth.
6.3. Drying shall be accomplished by exposure to ambient temperatures, or hot forced air or warming the parts in drying ovens or infrared lamps. A minimum period of 1 minute shall be provided to ensure that cleaning solution has evaporated prior to application of penetrant (Reference Doc:- Magnaflux MSDS Data Sheet )
7. Temperature Limits
7.1. The temperature of the penetrant materials and the surface of the part to be examined shall be between 50°F to 125°F (10°C to 52°C) throughout the examination period. Where it is not possible to comply with the temperature limitations, qualify the procedure for temperatures of intended use.
7.2. Local heating and cooling is permitted provided the part temperature remains in the range of 50°F to 125°F (10°C to 52°C)
8. Penetrants Applications
8.1. Apply the penetrant to the surface to be inspected so that the entire part or the area under examination is completely covered with penetrant. The application of the penetrant shall be carried out by spraying or brushing. For spray applications there should be proper ventilation at spray booths with exhaust systems.
8.2. The maximum penetration time or dwell time for penetrant shall be 10 minutes as required in Table 2 ASME Sec V, Article 24 for temperature range from 50°F to 125°F (10°C to 52°C).
8.3. In no case shall the penetrant be allowed to dry. During dwell time if necessary, the penetrant may be re-applied to ensure that the first coat does not get dried up. Unless otherwise specified, the dwell time shall not exceed the maximum recommended by the manufacturer.
9. Removal of excess penetrants
9.1. After the required penetrant dwell time, remove the excess penetrant as far as possible by wiping with a dry, clean lint free cloth or absorbent paper, repeating the operation until most of the traces of penetrant have been removed. Then lightly moisten a cloth or absorbent paper with cleaner and wipe the remaining traces gently to avoid the removal of penetrant from discontinuities.
9.2. Flushing the surface with cleaner following the application of penetrant and prior to developing is prohibited.
9.3. The part surface shall be allowed to dry by normal evaporation.
10. Application of Developer
10.1. The developer shall be applied as soon as possible after penetrant removal, the time interval shall not exceed 10 min.
10.2. Wet non-aqueous developer shall be used. Prior to applying the developer, the developer shall be thoroughly agitated to ensure adequate dispersion of suspended particles.
10.3. Application of developer shall be by spraying, to ensure complete coverage with a thin, even film.
10.4. Developer shall be applied only to dry surface. It shall be applied by spraying. Application of non aqueous developer by dipping and flooding is prohibited.
10.5. Drying shall be by normal evaporation
10.6. Development time for final interpretation begins as soon as developer coating is dry. Minimum developer dwell time of 10 minutes shall be provided and maximum permitted developer dwell time shall not exceed 1 hour.
Interpretation of Indications
11.1. It is good practice to observe the bleed out while applying the developer as an aid in interpreting and evaluating indications. Final interpretation shall be made within 10 to 60 minutes.
11.2. If the surface to be examined is large enough to preclude complete examination within the prescribed or established time, the examinations shall be performed in increments.
12. Light Intensity Requirements
12.1. A minimum light intensity of 100 fc (1000 lux) is required to ensure adequate sensitivity during the interpretation and evaluation of indications.
12.2. When natural illumination is inadequate, supplementary white light from a bulb of minimum 100 W held at about 90 deg to the examination surface at a distance not exceeding 300 mm shall be used for interpretation and evaluation of indications.
12.3. The light source , technique used and light level verification is required to be demonstrated one time, documented, and maintained on file.
13.1. Light meters shall be calibrated at least once in a year or whenever meter has been repaired. If meters have not been in use for one year or more, calibration shall be done before being used.
14. Evaluation of Indications
14.1. Unless otherwise agreed, it is normal practice to interpret and evaluate the discontinuity based on the size of the indication. Only indications with major dimensions greater than 0.019 inch (0.5mm) shall be considered relevant.
14.2. A linear indication is one having a length greater than three times the width.
14.3. A rounded indication is one of circular or elliptical shape with the length equal to or less than three times the width.
14.4. Any questionable or doubtful indication shall be re-examined to determine whether or not they are relevant.
15. Acceptance Standards
15.1. Acceptance shall be in accordance with AWS D1.1 :2000 or later, Section 6 for cyclically loaded connections or DIN EN 571 along with evaluation to ISO 5817, class 8.
15.2. Following acceptance standards as per DIN EN 571 along with evaluation to ISO 5817, class 8 shall apply
NOTE: An indication of an imperfection may be larger than the imperfection that causes it, however, the size of the indication is the basis for acceptance evaluation.
16. Repair examinations
16.1. After a defect is thought to have been removed and prior to making weld repairs, the area shall be examined by suitable methods to ensure it has been removed or reduced to an acceptably sized imperfection.
17. Re-examination of repaired area
17.1. After repairs have been made, the repaired area shall be blended into the surrounding surface so as to avoid sharp notches, crevices, or corners and reexamined by the liquid penetrant examination using this procedure.
18. Documentation and reports
18.1. Recording of Indications:
a) Non Rejectable Indications: Non Rejectable Indication shall be recorded in the report.
b) Rejectable Indications: Rejectable Indications shall be recorded as to type of indication (linear or rounded), length and location.
18.2. Penetrant Examination Report shall be prepared by at least NDE Level II qualified and certified as per Written Practice and shall contain information as following:
- Supplier Name, Address and Supplier Code
- Client Purchase/Shop Order Number and date
- Identification Number, Revision Level and Revision date
- SDR(s)/QCR(s) and the following
- Project Number (Contract Number) & Equipment Code
- Drawing Number
- Identification of Part Tested
- Material and thickness
- Liquid penetrant type and Family of Penetrant Materials Used
- Metal Temperature
- Dwell Time & Developing Time
- Lighting equipments
- Interpretation & Evaluation
- Signature with Date of the Person Performing, Interpreting and
- Evaluating the Penetrant test.
18.3. All reports/ records shall be maintained during production and during at least the following10 years for all components produced.
19. Post examination cleaning
19.1. All parts or areas examined must be cleaned and dried as soon as possible, however within 60 minutes, once the final interpretation and evaluation is completed.
19.2. The area examined shall be cleaned by wiping the developer with a cloth before it fixes on to the part. Repeat the process until most of the traces of developer are removed. Then, lightly moisten a cloth with cleaner and wipe the remaining traces. All traces of lint shall be removed.
19.3. The area cleaned shall be allowed to dry by normal evaporation.
20.1. Penetrant materials shall not be stored around hot surfaces, sparks and flames, as they are inflammable.
20.2. Do not breathe vapors or take internally as the penetrant materials are toxic in nature. Proper Ventilation at spray booths & exhaust system should be available for safe working conditions.