Penetrant nondestructive testing

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. 

R. C. McMaster, ed., "Liquid Penetrant Inspection," Nondestructive Testing Handbook, Vol. 2, 2nd ed., American Society for Nondestmctive Testing, Columbus, Ohio, and the American Society for Metals, Cleveland, Ohio, 1982. 

Corrosion-fatigue cracks can be detected by nondestructive testing techniques such as magnetic particle inspection, radiography, ultrasonics, and dye penetrant. Corrosion-fatigue cracks may occur in numerous tubes simultaneously. Nondestructive testing of tubes at locations similar to those in which cracks are observed can be useftil. 

Gross cracks may be visually observable. Nondestructive testing for the presence of cracks includes using dye penetrant, ultrasonics, and radiography. Determination of the cracking mechanism will require metallographic analysis. 

Caitz, L. Nondestructive Testing Radiography, Ultrasonics, Liquid Penetrant, Magnetic Particle. Eddy Current, ASM International, Materials Park. OH, 1995 Cornua, R.D. Problem-Solving Surface Analysis Techniques. Advanced Materials Processes, 16 (December 1992). 

Nondestructive evaluation, also termed nondestructive testing or nondestructive inspection, is extensively used in weld testing (14). Nondestructive tests do no impair the serviceability of the material or component under stress. The most widely used tests for evaluation of welds are liquid penetrant, magnetic particle, ultrasonics, and radiography. Acoustic-emission tests are increasingly used. Nondestructive tests detect and characterize, in terms of size, shape, and location, the various types of weld discontinuities that can occur. 

Preliminary testing is done next to uncover flaws in joining, and sometimes in the metal itself. Nondestructive test methods, such as ultrasonics and X- or gamma-ray inspection, are used on main welding seams Dye penetration, hydrostatic, or air-soap tests are also used to locals leaks and cracks. Helium or Freon leak detectors are necessary fok more critical leak testing, particularly on high-vacuum equipment. 

There are three common imperfections encountered in friction stirring voids, joint line remnants, and root flaws (or incomplete root penetration). The presence of voids is easily detectable by current nondestructive testing methods, but joint line remnants and root flaws... 

A form of nondestruetive testing in which the surface of a material is saturated with dye or fluoreseent penetrant and a developer is applied. The dyes bleed visibly to the surface indicating defects, while a fluorescent penetrant indicates the defects when an ultraviolet light is shown on them. See also Nondestructive Testing. 

The X-ray computed tomography, commonly abbreviated as X-ray CT, is a nondestructive testing method used to analyze the internal structure of objects. During testing, the examined object is X-rayed from different angles and the resulting set of projections is reconstructed to a three-dimensional volume (Fig. 7.1). The X-ray CT technique is based on the differentiation of different materials by their dissimilar X-ray absorption characteristics. After the penetration of the sample, the rays exhibit the transmitted intensity that is defined by the intensity of radiation /, the absorber thickness h, and the attenuation coefficient // according to the equation ... 

Nondestructive testing. An ultrasonic inspection technique is available for the detection of flaws in plate, piping, and tubing. The water-immersed pulse-echo ultrasound equipment has been adapted to highspeed use. Eddy-current, dye-penetrant, and radiogr.aphic inspection methods are also used as required. The inspected materials have included Inconel, austenitic stainless steel, INOR-8, and the Hastelloy and other nickel-molybdenum-ba.se alloys. 

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