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1. Scope of Application 1.1 This process is applicable only to the inspection of surface defects in workpieces. 1.2 This process is suitable for solvent cleaning-based coloring inspection. 2. Inspectors for flaw detection must receive technical training and hold a qualification certificate at level II or above for penetrant testing, issued by the Non-Destructive Testing Committee of the Ministry of Labor. 3. Materials for inspection: Inspection materials, grade, type – Penetrants: HD-RS, DPT-5 (solvent-based cleaning type); Cleaners: HD-BX, DPT-5 (solvents); Development agents: HD-EV, DPT-5 (quick-drying development agents). 4. Inspection conditions: 4.1 Inspection temperature – During the inspection process, the surface temperature of the workpiece should be between 15°C and 50°C. If the temperature is outside this range, adjustments shall be made in accordance with Appendix II of Part IV of the “General Procedures for Non-Destructive Testing”. 4.2 Surface requirements: The surface of the workpiece must be free of any foreign substances that could affect the test results, such as rust, scale, welding spatter, iron filings, burrs, and various protective coatings; if such substances are present, they must be removed by grinding to meet the requirements. 5. Inspection Steps 5.1 Pre-cleaning: After surface treatment, to remove contaminants from the surface of the workpiece, it is cleaned using a cleaning agent, and then dried by normal evaporation. 5.2 Application of penetrant: Use a spray can to apply the penetrant, ensuring that it covers the area to be inspected thoroughly and remains wet throughout the penetration time, which should be more than 10 minutes. 5.3 Cleaning: To remove excess penetrant, first wipe away the majority of it with a clean, lint-free cloth. The remaining amount should be gently wiped away using a clean cloth dipped in cleaning solution; care should be taken to avoid over-cleaning. 5.4 Application of the developer: Before use, shake the spray can to ensure uniformity. Keep the distance between the nozzle and the surface to be inspected at 300 mm–400 mm, and adjust the spraying angle to be 30°–40° relative to the surface. The developer should be applied in a thin and even layer; it must not be applied multiple times to the same surface. 5.5 Observation The observation should be carried out 15 minutes after the developer has dried; if the size of the visible traces does not change, the time limit can be exceeded. 6. Re-inspection 6.1 Re-inspection is required when one of the following situations occurs: a) At the end of the inspection, it is verified using a comparison block that the penetrant has lost its effectiveness. b) An error was found in the operating method during the testing process. c) When there is a dispute between the supplier and the buyer or when other needs are perceived. d) Parts that have been repaired. 6.2 When deciding to conduct a re-inspection, the surface to be inspected must be thoroughly cleaned to remove any residues from the previous test. 7. Post-treatment: Use a solvent to remove any remaining penetrant and developer. 8. Evaluation of the severity level of defect visibility marks. 9. Classification of defect visibility marks: a) Except where it is confirmed that the visibility mark is caused by external factors or improper operation, any visibility mark that is 0.5 mm or larger should be treated as a defect visibility mark. b) Defects with a length-to-width ratio greater than 3 that show traces are treated as linear defects ； Defects with a length-to-width ratio of 3 or less, which show traces, are treated as circular defects. c) When the angle between the long axis direction of the defect trace and the workpiece axis or generatrix is greater than 30°, it is treated as a transverse defect; otherwise, it is treated as a longitudinal defect. d) When two or more defect traces are on the same straight line and the distance between them is 2 mm or less, they are treated as one defect, with its length being the sum of the lengths of the two defects plus the distance between them. 10. The following defects are not allowed: a) any cracks and white spots ； b) Any transverse defects are shown. c) Any linear defects on the weld with a length greater than 1.5 mm are shown. 11. The grade evaluation for the cumulative length of defect display is as follows: Evaluation dimension 35×100; Grades I: 0.5, II: ≤2, III: ≤4, IV: ≤8, V: greater than Grade IV