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Inspection Inventory: A Closer Look At The Myriad of Methods of NDT

Posted by Shawcor North American Land NDT on March 09, 2018 8:00:00 AM

Inspection Inventory: A Closer Look At The Myriad of Methods of NDT
Inspection Inventory: A Closer Look At The Myriad of Methods of NDT

When it comes to creating safe, stable worksites, non-destructive testing, or NDT, is a must. Defined as testing that doesn’t change the material under inspection, this method is necessary for the secure construction of gas plants, pipelines, oil extraction equipment, and other volatile infrastructure. There are many different forms of NDT, each of which is suitable for various evaluations, including material assessments and regulatory compliance purposes. The most common conventional methods include:

Magnetic Particle Testing

Often abbreviated as “MT,” magnetic particle testing is a common method for finding defects on or immediately under the surface of ferromagnetic metals. It involves placing the pipe or other material of inspection under a magnetic field and then dusting iron fillings onto it. These fillings will gather along the edges of cracks and other compromised areas of the material. Inspectors can thus rapidly identify and correct defects with no risk to themselves or to the material being evaluated.

MT has the benefit of being compatible with an array of other inspection methods, including dry powder, wet fluorescent magnetic, and contrast technique inspections. It does, however, require specially-trained professionals. In particular, those performing MT must be able to achieve the correct alignment between the defect and the magnetic flux, and they need to know how to demagnetize the equipment after the inspection is completed.

Radiographic Testing

Radiographic inspection methods involve using X or gamma rays to inspect materials or equipment. Because these rays have exceptionally short wavelengths, they can easily pass through a wide range of materials that are otherwise hard to penetrate, including metals like carbon steel. This is ideal for detecting corrosion, welding imperfections, and insufficient wall thickness in pressure vessels, casting, and pipes.

The most effective forms of radiographic testing involve computed radiography, or real-time radiography, which uses computers to evaluate radiographic data and audit job sites and results remotely. Computed and real-time radiography technologies also decrease radiographic exposure times by up to 70 percent and developing times by 80 percent, leading to quick, accurate results.

Other NDT Options

Besides magnetic particle and radiographic testing, there are a number of other forms of NDT, including:

  • Liquid Penetrant Inspection- This method involves placing a liquid penetrant on the surface of a pipe or other asset. The liquid will then gather in cracks, dents, and defects, allowing operators to identify areas of concern.
  • Ultrasonic Thickness Testing- This NDT strategy is ideal for testing the wall thickness in pipes, vessels, and other materials. By emitting sound waves and measuring how long they take to return to the emission source, inspectors can determine how thick materials are overall, as well as whether there are any particular areas that are potentially at risk.
  • 3D Laser Scanning- Using lasers, it is possible to identify pits in metal assets and to determine how deep they are. This helps operators find out both whether corrosion has occurred, the rate at which the corrosion is occurring, and where it is most serious.

Shawcor has the training and resources to perform a wide range of NDT inspections on numerous assets and materials. For more information or to request our services, contact us today.

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