At Highland Equipment, our team employs a wide range of NDT methods, allowing us to meet and exceed the highest inspection requirements.

What Is Nondestructive Testing (NDT)?

Nondestructive testing, also known as nondestructive examination, nondestructive inspection, and nondestructive evaluation, is non-invasive inspection that evaluates equipment without damaging it. It is made up of a range of different inspection techniques and can test for a variety of different failure mechanisms, such as cracks, inclusions, porosity or corrosion, that may cause long-term problems or mechanical failure. NDT can also be utilized to evaluate the material properties of various types of equipment.

The main goal of NDT is to ensure the long-term functionality of equipment components in a secure, economic way. Unlike destructive testing, NDT causes no damage to the component being examined; in fact, NDT can frequently be performed on equipment without halting plant operations. Due to its non-invasive nature, NDT can be performed on equipment that is currently in service, as well as on equipment that has just been manufactured.

There are two categories of NDT—conventional and advanced. Each category is composed of a series of different tests and techniques. Conventional NDT techniques have been used for decades and are well-established by industry professionals. Advanced NDT techniques, on the other hand, are newer and have few, if any, best practices, and little codification within the industry. It is important to note that the following NDT methods generally involve plant operational shut down.

Highland Equipment’s NDT Methods

At Highland Equipment, we employ the following NDT methods:

  • Borescoping
  • Dye Penetrant
  • Pressure Testing
  • Radiography (X-Ray)
  • Ultrasonic Testing (UT)


Borescoping—is a technique where an inspector can visually examine a component that is inaccessible or difficult to see. Borescopes are comprised of a visual display, a rigid or flexible tube, an electrical system, and an objective lens or camera.

Most frequently, inspectors utilize borescopes to examine turbines, engines, and other industrial parts that have stringent maintenance requirements. At Highland Equipment, we typically use state-of-the-art borescoping equipment to internally examine piping in order to ensure our welds meet and exceed the high standards we set for ourselves.

Dye Penetrant

Dye Penetrant Inspection, or DPI, is a portable and economical way to test components for surface breaking flaws. To utilize this method, an inspector will clean the component and then apply the dye by brushing, dipping, or spraying. After this, the inspector applies a developer, which draws the penetrant to the surface and makes it possible to visually inspect the component for defects.

DPI tests for many surface flaws, including seams, cracks, and porosity. It is a beneficial technique because it can be used on all non-porous materials, as well as both ferrous and non-ferrous materials.

Pressure Testing

Utilized for pipeline and vessel inspections, pressure testing gauges the reliability, pressure, joint fittings, and maximum capacity of the piping or vessel before it is put into service. This method uses either incompressible liquids such as oil or water, or compressible fluids like air, argon, nitrogen etc. to help inspectors more easily detect leaks.

Pressure testing always puts piping or vessels under significantly more pressure than they normally operate with, which provides more safety because it accounts for pressure variations and ensures the strength of the piping and vessels.

X-Ray (Radiography)

Industrial radiography utilizes X-rays to detect flaws that would otherwise be invisible to the naked eye. More specifically, X-rays can help inspectors find areas of equipment that are thinning or beginning to crack. This method is ideal for testing components that are difficult to access, as the X-rays can travel through metal, soil, air, and water. At Highland, images of welds that are created from radiography are used to identify cracks, incomplete fusion, inadequate penetration, porosity and slag inclusion within a welded joint. Radiographic inspection is used not only to look for weld defects but also to determine welded joint efficiency factors that can be used in calculations for designing pressure components, vessels and piping. For example, in our calculations for ASME Section VIII pressure vessels we can choose to design with three levels of radiographic weld examination in mind; no radiography, spot radiography or full radiographic examination.  The greater the level of radiographic examination you intend to use in your design, the greater the maximum allowable joint efficiency you are allowed to claim in your calculations.  Greater joint efficiencies, result in being able to use thinner parent materials to construct the pressure component or vessel.

Working With Highland Equipment

For everything we do, we set and maintain incredibly high inspection standards. Our team of engineers is dedicated to providing customers with the very best. We hold a number of certifications from the Technical Standards and Safety Authority, as well as the American Society of Mechanical Engineers.

To learn more about inspections or to work with us on your next project, contact us today.