What is NDT?

Non-Destructive Testing (NDT) is an inspection, testing, and analysis technique. Sometimes called Non-Destructive Examination (NDE), it is commonly used in the oil and gas, manufacturing, aircraft, pulp and paper, construction, and mining industries.

An NDT inspection evaluates and determines an asset’s wall thickness and identifies weld weaknesses. It is a cost-effective, reliable, accurate, and safe way to check for corrosion, metal fatigue, and material anomalies.

Why is it Important?

Protecting your workers, the public, and the environment is your highest priority. NDT inspections help by finding defects and flaws in an asset you cannot visibly see early. The process used does not damage assets. For example, an NDT inspection crew can inspect a pressure pipe many times in many different areas of the pipe, and afterward, it can be returned to service.

In contrast, Destructive Testing, such as impact resistance testing, usually ends up with the asset being damaged to the point it can no longer be used for service. This is an important test for understanding the potential performance of an asset under different scenarios but is quite different in nature from its non-destructive counterpart.

Types of NDT Inspections

Here are the most common NDT inspections s used in the oil and gas industry.

VI (Visual Inspection)

To look (eyes only) at something without using any additional inspection instruments. VI is a very effective technique for detecting surface flaws such as coating imperfections.

UT (Ultrasonic Testing)

Transmits high-frequency sound waves into a material to detect imperfections or to locate changes in material properties.

MPI (Magnetic Particle Inspection)

Cracks or defects are found by establishing a magnetic field in the object and using iron filings to see if the field lines are constant.

ET (Eddy Current Testing)

An electromagnetic technique used on conductive materials for crack detection or the rapid sorting of small components for either flaws, size variations, or material variation, as well as other applications.

RT (Radiography Inspection)

Uses gamma or X-radiation on materials to identify imperfections.

PT (Penetrant Testing or Dye Penetrant Testing)

Applying liquid or dye to an asset reveals surface-breaking flaws by a “bleedout” at the imperfection location.

LT (Leak Testing)

A technique to detect and locate leaks in pressure containment parts, pressure vessels, and structures using pressure gauges, soap-bubble tests, or electronic listening devices.

AE (Acoustic Emission Testing)

Acoustic emissions identify possible defects and imperfections in a material.

Why Should You Conduct NDT Inspections?

There are many benefits of conducting NDT tests. The most important, of course, is the prevention of incidents, which improves safety for the public, your workers, and the environment. But there are other benefits, and we encourage you to invest in this affordable, safe, reliable, and accurate inspection program.


  • It’s a cost-effective way to understand the integrity of your materials. It does not damage them, and they can return to service after being tested.
  • NDT saves you money. You can track inspection results through the asset’s lifetime, allowing for decreased inspection intervals that are determined by risk level.
  • Your workers spend more time on tools. NDT requires little interruption to workers and equipment, meaning less downtime.
  • NDT improves maintenance scheduling. By identifying areas of high risk, you can direct corrective actions to those ahead of other less critical issues and before a structural failure occurs.
  • An NDT program will protect against the consequences of regulatory non-compliance. This could include fines, downtime while regaining compliance, and reputational risk.


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