Liquid penetrant testing method

This method consists of application of liquid to the surface of a sample, allowing the liquid to penetrate into the discontinuities in the sample. After some time the excess liquid on the surface is removed, leaving the liquid in the discontinuity intact. Then a developing agent is applied, which draws the liquid penetrant from the discontinuity to the surface of the sample, leaving a visible indication of the discontinuity on the sample. The liquid penetrant usually consists of a colored dye to enable ease of detection in either visible or ultraviolet light. 

The method can locate discontinuities open to the surface in porous materials. It is possible to detect porosity, surface cracks and through leaks, which may result from fatigue cracks, shrinkage porosity, cold shuts, grinding and heat-treat cracks, seams, forging laps and bursts as well as improper bonding between joined metals. 

The method has been successfully used in detection of flaws in Al, Mg, Cu, brass, cast iron, stainless steels and titanium. This method can also be used in testing ceramics, plastics, rubber products, powdered metal products, as long as it is borne in mind that the method is limited to the detection of open discontinuities on the surface and limited to materials devoid of porous surfaces. 

The true indications of the discontinuities may appear as continuous lines due to cracks, cold shuts, forging laps, scratches or die marks. 

Cold shuts Smooth, narrow straight lines 

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General corrosion control, prevention, and monitoring should be planned for from the onset. To detect and monitor corrosion, various methods must be used, while corrosion protection would be done by the addition of inhibition and use of protection coatings [5]. Visual examination, laser methods, the replication microscopy liquid penetration testing method, magnetic particles testing, the eddy current inspection method, acoustic emission technique, thermal methods of inspection, and nondestructive methods are the various methods to be adopted when monitoring pipeline corrosion [5]. 

General hydrodynamic theory for liquid penetrant testing (PT) has been worked out in [1], Basic principles of the theory were described in details in [2,3], This theory enables, for example, to calculate the minimum crack s width that can be detected by prescribed product family (penetrant, excess penetrant remover and developer), when dry powder is used as the developer. One needs for that such characteristics as surface tension of penetrant a and some characteristics of developer s layer, thickness h, effective radius of pores and porosity TI. One more characteristic is the residual depth of defect s filling with penetrant before the application of a developer. The methods for experimental determination of these characteristics were worked out in [4]. 

EN I SO 6530 2005 Protective clothing - Protection against liquid chemicals -Test method for resistance of materials to penetration by liquids. 

Liquid penetrant inspection. The liquid penetrant NDE method is apphed to detection of faults that have a capillary opening to the test object surface. The nature of this NDE method demands that attention be given to material type, surface condition, and rigor of cleaning. Liquid penetrant inspection can be performed with little capital expenditure, and the materials used are low in cost per use. This technique is applicable to complex shapes and is widely used for general product assurance. 

Nondestructive testing techniques for welded joints usually include visual, radiographic, magnetic particle, liquid penetrant, and ultrasonic testing methods. Of interest in this paper is the radiographic testing (RT) technique. 

After sueeessful eompletion of all testing, eaeh rotating assembly must be disassembled for visual inspeetion of the rotor, bearings, and seals. Oversped wheels should be examined by the liquid penetrant method. 

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. 

American Society for Testing and Materials, Standard Test Method F903-87-Resistance of Protective Clothing Materials to Penetration by Liquids, American Society for Testing and Materials, Philadelphia, 1987. 

If pneumatic pressure testing is to be done, all radiographable welds are examined completely by this method and all others by the magnetic particle or liquid penetrant method. Failure during a pneumatic pressure test simply cannot be permitted. 

A variety of test methods have been developed that measure a fabric s resistance to liquid penetration. However, manufacturers, trade associations, and government agencies do not agree as to which test method is the best predictor of liquid barrier performance, particularly in the surgical environment. 

ASTM FXXXX (draft) Standard Test Method for the Resistance of Protective Clothing Materials to Biological Fluids conducted at 1 psi (based on ASTM F 903) The fabric is subjected to a liquid at 0 psi for 5 min, at 1 psi of pressure for 1 min, and at 0 psi for 54 min. Time of penetration is recorded. 

Methods for sealing the metal surfaces of the test devices against nonwoven fabrics should be explored because leaks may be confused with penetration and recorded as a test failure. Test methods which quantify the liquid penetration rather than detect it with visual inspection should be developed and compared with others. 

ASTM F903-10, Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Liquids Procedure C. 

Liquid-Penetrant Inspection is a method of testing for surface defects or sub-surface defect with surface openings by relying upon a penetrant seeping into the defect. It is normally used for non-magnetic materials. 

Penetrant testing - this method uses a penetrant dye applied to a pre-cleaned surface. The liquid penetrant which has high surface wetting characteristics is pulled into surface... 

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