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INSPECTION TRENDS — July 2005 — Summer · Volume 8 · Number 3

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Summer Features

YOKE MT: Part II —
Preparing for Inspection
by G. E. Smith and U. Aschemeier
Magnetic particle testing (MT) is probably the most used form of nondestructive examination of welds other than visual inspection and is a natural companion to visual inspection. As you prepare to perform MT, keep in mind that knowledge of the test item is crucial to the successful performance of magnetic particle tests. A knowledge of the test variables for basic weld inspection, including pole spacing and shape; magnetic field strength; dry-, water-, or oil-based magnetic media (particles); media color or fluorescence; and media shape and particle size, can affect the selection of MT. Development of effective test procedures is the job of the NDT Level III and those persons who write codes and specifications.

The Effect of Geometric Unsharpness on Radiographs
by B. Zoofan
The concept of geometric unsharpness in radiography is a major topic in any radiographic text book. Still, for trainees and students who have just been exposed to this concept, the principles of geometric unsharpness and their effect on the quality of radiographs are difficult to understand.

Geometric unsharpness (U_g) is simply the amount of blurriness in a radiographic image due to the finite size of the radiation source or the geometrical configuration of the exposure setup. There are different sources of unsharpness in radiography, but, compared to others, geometric unsharpness is the most dominant factor. Indeed, at the early stage of the discovery of X rays, this new technique was called shadowgraphy.

In the Beginning...
by C. J. Hellier
Nondestructive testing (NDT) features a broad, diverse, and interesting history. Each of the many examination methods had a unique beginning. There were many pioneers who discovered individual methods, and many more who developed and improved those methods out of necessity and the quest to find more — and smaller — discontinuities.

So exactly when did NDT begin? Many believe that the first, and probably the most important, NDT was performed as described in the biblical account found in the book of Genesis. In describing the process of creation, Chapter 1 repeats the expression "and God saw that it was good" six times. That first nondestructive test is known today as visual testing (VT).

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INSPECTION TRENDS
(ISSN 1523-7168) is published quarterly by the American Welding Society. Editorial and advertising offices are located at 550 N.W. LeJeune Rd., Miami, FL 33126; telephone (305) 443-9353. Printed by R. R. Donnelley & Sons Co., Senatobia, Miss. Subscriptions $30.00 per year for noncertified, nonmembers in the United States and its possessions; $50.00 per year in foreign countries; $20.00 per year for noncertified members and students; $10.00 single issue for nonmembers and $7.00 single issue for members. POSTMASTER: Send address changes to Inspection Trends c/o American Welding Society, 550 N.W. LeJeune Rd., Miami, FL 33126-5671.

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