Liquid penetrant examinations

Liquid-Penetrant Examination This examination shall be performed in accordance with Art. 6, Sec. V of the ASME Code. 

Liquid-penetrant examination involves wetting the surface with a fluid which penetrates open cracks. After the excess liquid has been wiped off, the surface is coated with a material which vidll reveal any liquid that has penetrated the cracks. In some systems a colored dye will seep out oi cracks and stain whitewash. Another system uses a penetrant that becomes fluorescent under ultraviolet hght. 

All circumferential and longitudinal butt welds of pressure containing casings shall be 100% radiographed, if possible. All other welds shall be magnetic-particle or liquid-penetrant examined. 

Liquid Penetrant Examination. All accessible surfaces of the main load carrying components of the equipment shall be examined by a liquid penetrant examination or technique conforming to the requirements of ASTM E165 Recommended Practice for the Liquid Penetrant Examination Method. Acceptance limits shall be as agreed upon by the manufacturer and the purchaser. 

Liquid penetrant examination (for ferrous or nonfer-rous materials) shall be performed based on the following requirements ... 

Liquid penetrant examination shall be performed on all welds connecting to hydrogen piping system components which are not radiographed. 

Plate edges shall be inspected by magnetic particle or liquid penetrant examination as required by Section VIII, Division 1, UG-93(d)(3), of the ASME Code. 

NDE shall be performed as required by the material specification. If additional radiographic, ultrasonic, magnetic particle or liquid penetrant examinations of the welds or materials are specified by the purchaser, the methods and acceptance criteria shall be in accordance with the standards shown in Table 13. Alternative standards may be proposed by the vendor or specified by the purchaser. The welding and material inspection data sheet in Annex N may be used for this purpose. 

By comparison with other NDC methods, such as liquid penetrant examination, magnetic particle, eddy current testing, and radiography, the ultrasonic method is the only technique that is applicable to a wide range of materials. 

Liquid penetrant examination or magnetic particle methods and 100% volumetric examination by ultrasonic methods will be conducted at about ten-year intervals during the plant shutdown coinciding with the in-service inspection schedule as required by the ASME Code, Section XI. 

The canister water level is lowered slightly, the canister is vented, and the canister lid is seal-welded using an automated welding system. Liquid penetrant examinations are performed on the root and final passes. An ultrasonic or multilayer liquid penetrant examination is performed on the canister lid-to-shell weld to ensure that the weld is satisfactory. The canister lid-to-shell weld is then pressure-tested followed by an additional liquid penetrant examination performed on the canister lid-to-shell weld to verify structural integrity. 

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