Destructive and Nondestructive Testing Methods: A Comparison

When comparing destructive and nondestructive testing, destructive testing is, in some ways, the most reliable method. However, nondestructive testing (NDT) retains a significant advantage over destructive testing because it covers more ground and saves on material costs. With NDT, analysts can avoid damaging assets and find more flaws in the process. Destructive testing is ultimately more expensive and wasteful, as inspectors must damage viable materials that could have been used during normal operations. Moreover, destructive-means testing is also less efficient than NDT in terms of inspection times, involving manual steps that take longer and require more effort than the streamlined processes NDT can offer.

Let’s take a closer look at how the two approaches measure up against each other.

Probing with a Wider Reach

Destructive testing is a more direct approach, but it cannot provide the same extensive reach that NDT tools offer. If dealing with destructive testing on large infrastructure, an analyst must destroy aspects of the welds to find hidden flaws. It can be all too easy to miss indications on larger design forms, and inspectors don’t have the time to conduct such a thorough manual test.

Furthermore, the inspector would have to compromise key structural points of the infrastructure, which could degrade the viability of the asset and lead to safety concerns in the future. The companies would also likely need to invest additional time and resources to replace the parts that underwent destructive testing. This is not the ideal option when dealing with a sizable infrastructure that costs millions of dollars.

On the other hand, there is a better option:

Example: An NDT company has been hired to conduct regular inspections on an oil pipeline. Using long-range ultrasonic testing, an analyst detects corrosive anomalies over 50 feet away, including the location of the aberrations. Then, the analyst isolates the piping section and uses a corrosion scanner to further profile the flaws.

Ultrasonic testing is a noteworthy NDT method that fosters long-range methods. It should be noted that the long-range technique has its limitations, but it provides a solid guiding mechanism on flaw location. After, inspectors should follow up with portable NDT instruments that can highlight the full nature of the flaws or detect wall thickness measurements.

A destructive-means test could never detect flaws from long distances, as inspectors must interact directly with the object being tested. With ultrasonic technology, a user can obtain the necessary data from a single location.

In addition to oil pipelines, NDT can cover the following other types of large infrastructure, such as:

  • Oil rigs
  • Nuclear power generation plants
  • Railroad tracks
  • Walls

Nuclear plants are particularly noteworthy because the long reach of ultrasonic keeps personnel away from radioactive zones. Nuclear experts may also use another NDT method known as eddy current testing (ECT), which can test such materials as steam generator tubing without interfering with the structural integrity of steam generators.

Eddy current instruments can also find surface and sub-surface abnormalities, as they are easily able to probe for deviations behind walls or underneath protective coatings. This also prevents personnel from dealing directly with wiring or other conductive elements that can be dangerous to work with.

With destructive testing, inspectors would have to scrape away the paint layers or break down walls to reach an asset. This isn’t to say that NDT is exempt from layer removal entirely, as NDT methods like magnetic particle testing require the removal of painted surfaces before testing. But advanced NDT techniques such as ECT and UT require only minimal prep time and efficient testing parameters.

Time-Saving Strategies

In addition to covering more ground, NDT spares analysts the laborious task of breaking down materials for testing purposes. Companies with vast numbers of products or equipment to inspect don’t have the time to manually test every single item in their inventories. Besides which—why would companies risk damaging all of that valuable equipment when NDT renders it unnecessary to do so?

Plus, destructive testing requires companies to shut down operations to accommodate the testing process. This is a daunting task that hampers operations and costs a company vital hours for each minute a machine isn’t in operation.

This is where NDT plays a major role in ensuring smooth and timely operations, as the instruments can test many items with minimal interruption to operations. With a portable instrument, users can probe nearly every part of the object. Certain NDT methods are advanced to the point where inspectors can achieve instant data with a single pass of the instrument.

NDT instruments also provide a level of flexibility that is often key in detecting hard-to-find flaws.

Example: An inspector must test an engine that has flush rivet rows and weld toes. To conduct a destructive test, the inspector would have to break down the item, absorbing more time than needed while compromising the design form—and the engine would cost thousands of dollars to replace. With ECT surface array technology, however, the analyst can use a probe coil set to inspect the rivet rows with ease. That same instrument also accepts +point coils that can inspect weld toes in less time, producing impeccable data in the process. 

Overall, NDT saves on time and labor hours that, if a company utilized a destructive testing method, would have been devoted to reassembly—not to mention the costs involved in repairs and replacements.

Destructive and Nondestructive Testing Reliability

Innovative NDT techniques such as eddy current technology and ultrasonic technology have sensitive signals that can detect more aberrations in less time than destructive testing can hope to achieve. Between destructive and nondestructive testing, destructive testing provides reliable results, but its manual process and material degradation procedures cost companies a great deal in terms of time and money that can easily be saved with an NDT approach.

With NDT, inspectors can detect surface, subsurface and volumetric indications using the latest software that provides a simple interface and automated procedures. Plus, NDT allows inspectors to quickly and accurately detect aberrations that could lead to costly damage in the future—allowing companies to address deviations before they turn into problems that can endanger the public and staff personnel.

Zetec is a leading provider of NDT solutions that foster enhanced testing procedures. Contact Zetec today to get stellar equipment and a custom NDT inspection plan that conforms to your company’s specific needs.

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