Types of Ultrasonic Non-Destructive Testing (NDT) Techniques

The technology of ultrasonic testing has been used by production and industry since the development of the radio engineering process. The effect and device of the technology are that ultrasonic waves of acoustic type do not change the rectilinear trajectory of motion when passing through a homogeneous medium.

The ultrasonic method is also used to check metals and compounds with different structures. Such cases imply that there is a partial process of reflection of waves, depending on the chemical properties of metals, the greater the resistance of sound waves, the stronger the effect of reflection.

Ultrasonic testing or Ultrasonic nondestructive testing does not destroy the structure of the joints. The technology of ultrasound diagnostics includes the search for structures that do not correspond to the chemical or physical properties of the indicators, any deviations are considered a defect.

Vibration readings are calculated according to the formula L = c / f, where L describes the wavelength, the speed of movement of ultrasonic vibrations, and f as the vibration frequency. The defect is determined by the amplitude of the reflected wave, thus it is possible to calculate the size of the defect.

Ultrasonic Testing: Various Types

Automated Ultrasonic Backscatter Technique (AUBT)

It is a type of ultrasonic testing method created to detect the damage from High-Temperature Hydrogen Attack (HTHA). This method can be used in pressure piping and vessels. It uses a digital oscilloscope, broadband UT probes, and high frequency. This enables it to offer frequency analysis and A-Scan display.

Phased Array Ultrasonic Testing (PAUT)

It is ultrasonic testing that considers different ultrasonic testing probes created by different elements (small size). Every element in the PAUT solution can pulse separately. This is carried out with the computer computation technique with the method termed Phasing. It enables the solution to drive focused beams from various focal distances and different angles.

Long Range Ultrasonic Testing (LRUT)

As one of the types of ultrasonic, LRUT enables testing of the extensive amount of material from one testing point. This technique operates by uniformly fixing the transducer rings nearby the pipe. The rings then produce guided waves of low frequency. Later, the waves propagate around the pipe symmetrically. It offers overall pipe wall coverage.

Internal Rotating Inspection Systems (IRIS)

This technique of ultrasonic testing is used for detecting corrosion in tubing and piping. It is done by the internal inserted probe that creates sound waves. The system operated with probe insertion in the flooded pipe. From the pipe, the probe moves, and scans where it is going.

Time of Flight Diffraction (TOFD)

It is the technique used for looking into the defects in the welds. TOFD leverages the time of flight of the ultrasonic pulse for finding the reflector location. To know the TOF, the technique uses ultrasonic transducers. The transmitter emits fewer frequency waves that propagate at an angle. They differentiate back to the receiver if they are hitting the defect.

Dry-Coupled Ultrasonic Testing (DCUT)

DCUT is a low-cost and alternative technique that does not need a liquid couplant to find nonmetallic and metallic material. In addition, DCUT transducers are able to withstand high voltage. It is a flexible technique that could be operated with contact, flexible, remote transducers, and wheels.

• Manageable transducers could be applied on an internal or external component surface for finding the defects.
• Contact transducers are used for detecting defects and density measures.
• Wheel transducers enable inspectors to find the long piping systems in less span of time.
• The remote transducers are beneficial as they can get thickness calculations at non-conventional angles. These are the ones that are 90° to the surface. This reduces the requirement to remove or support components to carry out inspection.

Rapid Ultrasonic Gridding (RUG)

It is the type that performs ultrasonic thickness in which several ultrasonic thickness probes are used to quickly collect thickness requirements in ad hoc or predefined space. Similar to different ultrasonic testing techniques, Rapid Ultrasonic Gridding gets A-Scan data that could be performed in B or C scan modes, or for creating visual needs as 3-D models. Though, it can capture different A-Scan data points at more frequency as compared to the thickness measuring methods.

Scope of ultrasonic inspection

This control method is used in the industrial sector, as well as in the reconstruction and construction of houses. It is often used:

• For analytical diagnostics of units and assemblies.
• To determine the wear of pipes in the main pipeline.
• In nuclear or thermal power engineering.
• In the field of mechanical engineering, oil, and gas, chemical industry.
• When checking welded joints of structures with a complex configuration.
• When diagnosing metal compounds with a coarse-grained structure.
• When welding joints of units and boilers of equipment, which are under the influence of pressure, high temperature, aggressive environment.

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