Testing Without Destruction
Testing Without Destruction
Automotive parts and designs are often crash-tested to see how well they will stand up in the event of an accident. Furniture and other flammable products are burn-tested before use to determine how well they limit fire and other damage. And aggressive environmental testing can help determine the effect that weather and other environmental factors will have on a given product over its usable life.
These types of tests can generate reams of data. In many cases, however, they also generate a destroyed product.
But product testing doesn’t have to result in damage. Nondestructive testing (NDT) methods including X-ray, radiology, liquid penetrant, ultrasonic, electromagnetic, visual examination, and more can offer manufacturers insights into the performance and structure of their products without having to burn them to the ground in the process. These types of tests fall under the purview of the committee on nondestructive testing (E07). Formed in 1938, the committee maintains jurisdiction over 225 standards covering both traditional and emerging testing methodologies including radiology, liquid penetrant, magnetic particle, acoustic emission, ultrasonics, electromagnetics, leak testing, and reference radiological images.
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Not surprisingly for a committee that has existed for nearly a century and manages standards that impact a wide range of industries, its constituency varies widely.
“People that make lawn mower parts can use these standards, and people that put parts on the space shuttle can use them too,” says Curt Powell, longtime committee member and chair of the subcommittee on liquid penetrant methods (E07.03).
At a high level, E07 is tasked with developing standard specifications, test methods, practices, guides, terminology, and other reference material related to a growing range of nondestructive testing methods and applications. Among these are two that, according to committee leadership, are among the most asked-about of the committee’s standards: standard practice for liquid penetrant testing (E1417) and the standard practice for magnetic particle testing for aerospace (E1444).
On the surface, the two couldn’t appear less related. While E1417 covers a liquid film to detect surface discontinuities, E1444 offers a standard practice for the aerospace industry. But, as Powell explains, both serve a similar purpose to the industries that use them the most.
For instance, E1417 tests the surface of a specimen for fissures, porosity, tears, etc., and different testing materials will provide various sensitivity levels of inspection. So while an aerospace manufacturer might be looking for very fine discontinuities and may impose a higher sensitivity level such as Level 3 or Level 4, an industrial product might only require a lower sensitivity range because it is not as critical to inspect everything as closely in those applications.
“E1417 makes it easy for the person trying to purchase a product or service to simply say, ‘I want my product to be inspected for these discontinuities using E1417 at this sensitivity level,’” says Powell. “And within the eleven pages of that document, with the exception of acceptance criteria, it's all there. It talks about whether you have to train or certify your people, the different types of materials you can use to meet your sensitivity goals, the process control requirements, the recordkeeping, how to identify a product that was rejectable versus acceptable, etc. It’s one-stop shopping.”
E1444 offers effectively the same benefits except for magnetic particle testing instead of liquid penetration.
These types of standards have proven to be extremely helpful for companies that are trying to set up an NDT facility. Instead of having to rewrite the whole procedure for that company, it's typically easier for companies to align their inspection procedures with these two standards and use them as the basis for their own procedures. As long as they are following the standard practice based on their end goals, their NDT needs have been met.
“It’s all there,” Powell says. “As a user, you can open up to the first page and the standard takes you by the hand through how we created each process, what control checks were used, and all the other documentation you might need.”
Given that functionality, it’s no surprise that both of these standards have emerged as industry standard templates in the field of nondestructive testing.
Tim Sprinkle is a freelance writer based in Colorado Springs, Colorado. He has written for Yahoo, The Street, and other websites.