T9074-AS-GIB-010/271 Rev 1
5.6.6 Surface Drying.
5.6.6.1 Method C. The drying of test surfaces after the removal of the excess penetrant shall be accomplished by normal evaporation, or by blotting with absorbent paper or clean, lint-free cloth. Forced air circulation in excess of normal ventilation in the inspection area shall not be used. Unless otherwise specified by the penetrant manufacturer, the time for surface drying after removal of excess penetrant and prior to application of the developer shall not be greater than 10 minutes. 5.6.6.2 Methods A, B, and D. The drying of test surfaces shall be accomplished by using hot-air recirculating ovens, circulating air, blotting with paper towels or clean lint-free cloth, or by normal evaporation. If a drying oven is used, the temperature shall not exceed 160 °F. It is important that during the drying operation, no contaminating material be introduced onto the surface that may cause misinterpretation during the inspection operation. The time for surface drying operation shall be in accordance with the manufacturer's instructions.
5.6.7 Application of Developer. For Method C liquid penetrant inspections, only nonaqueous wet developers shall be used.
5.6.7.1 Nonaqueous Wet Developer. Surfaces shall be dry prior to application. Immediately prior to application, the developing liquid shall be kept agitated to prevent settling of solid particles dispersed in the liquid. The developer shall be uniformly applied in a thin coating to the test surface by spraying. If the geometry of the item being inspected precludes the use of a spray, a brush or similar applicator shall be used provided it results in a uniform, thin coating of developer. Pools of wet developer on the inspection surface shall not be permitted. Inspection shall be performed not less than 7 minutes and not greater than 30 minutes after the developer has dried. 5.6.7.2 Dry Developer. Dry developing powder shall be applied only on dry surfaces so that matting will be prevented. The powder shall be thinly but uniformly applied to provide a dusty appearance immediately after drying of the test surface. Inspection shall be performed not less than 10 minutes and not greater than 30 minutes after the developer has been applied. 5.6.7.3 Aqueous Wet Developer. This type of developer shall be uniformly applied to surfaces by dipping, spraying, or brushing as soon as possible after removal of all excess penetrant but in no case to exceed 10 minutes. Time for development of indications after the aqueous developer has been applied and dried shall not be less than 10 minutes and not greater than 30 minutes. The surface may be dried prior to the application of the aqueous wet developer, but this is not necessary. When using liquid-type developers, it is necessary that they be continually agitated in order to prevent settling of solid particles dispersed in the liquid. Pools of wet developer on the inspection surface shall not be permitted. 5.6.8 Lighting in Test Area. When using the visible dye penetrant method, the test area shall be adequately illuminated for proper evaluation of indications revealed on the test surface. Due to the fact that some light-emitting diodes (LED) lights have been found to impair color contrast of indications, specific use of these types of lighting sources and other light sources that impair contrast of indications or adversely impact test results shall be approved by the activity’s NDT Examiner, or the Examiner's designated representative. When fluorescent penetrant is used, the inspection shall be accomplished in a darkened area using a black light (ultraviolet light). The black light shall be capable of producing an intensity of 800 microwatts per square centimeter on the inspection surface. Intensity of the black light shall be measured daily when used, and after bulb replacement. For battery operated black lights, the NDT Examiner shall include a process in the procedure to ensure the depleting battery life does not result in an unacceptable black light intensity during inspections. Not less than 5 minutes shall be allowed for the black light lamp to obtain full brilliance before the lamp is used for any part of the inspection. For LED and other black light sources that do not require a 5-minute warm up, the NDT Examiner shall approve and document an alternative warm up time in the procedure. 5.6.9 Final Cleaning. When the inspection is concluded, the penetrant materials shall be removed as soon as possible by means of water or solvents as specified in 5.6.2 and with applicable cleaning specifications. 5.6.10 Safety Precautions. Penetrant inspection materials shall be used in accordance with all applicable safety regulations.
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