8 June 2022

Ultrasonic inspection of welds

The most vulnerable point in pipelines are the welds connecting the two parts of the object to each other. Defects in welded joints can lead to catastrophic consequences, the damage from which can be measured in millions of rubles. To examine the welds for cracks, voids and other defects, it is possible by flaw detection.

This procedure is performed in various ways, but the most accurate and common is non-destructive ultrasonic testing. It does not require large resources, is the most versatile and allows you to determine the exact coordinates of defects and residual resource. Flaw detection is carried out at the production stage to exclude defects, as well as during operation after a certain period of time.

In what cases and for what purpose is it carried out

Ultrasonic inspection is a standard procedure for checking the quality of welding. It is carried out in three cases:

  • during production - it is necessary to avoid defects in the sale of metal structures, tanks and pipelines, to check their compliance with state standards and loads;
  • during operation - regular technical inspections include a special inspection to check the reliability of welding in working conditions. This allows you to identify pockets of corrosion, cracks and other defects that develop due to the influence of the external environment;
  • if a defect is suspected - if the structure is not fully operated, or becomes the cause of problems, it must be examined to identify the focus. Flaw detection will determine the location and extent of the lesion.

The peculiarity of welded joints is their dependence on external and internal operating conditions. Designed for a certain load, they are able to withstand it for a long time. However, even the slightest weakening in the form of foreign inclusions, voids, cracks or pockets of corrosion can lead to the destruction of the object. It is possible to prevent this at an early stage by identifying defects using ultrasound diagnostics.

This is especially important in the manufacture of products for large industrial facilities - load-bearing structures for construction, railway rails, pipelines for gas and fuel, elements of nuclear and chemical reactors. Flaw detection is widely used in many areas - in the oil and gas industry, mechanical engineering, nuclear power.

Advantages of this type of control

  • speed - inspection of seams with a flaw detector depends on their volume and the model of the device. However, in all cases, it will go faster than analog devices will be capable of. This is especially important for working in a short time or in a dangerous environment, where you need to get results as quickly as possible;
  • accuracy - flaw detectors determine the type, depth and spread of the defect. The data obtained make it possible to find the root cause of such problems and eliminate it, as well as prevent the destruction of the structure;
  • accessibility - flaw detectors are quite compact and easy-to-use devices, and the procedure itself is inexpensive. It is much cheaper to eliminate the consequences of the destruction of the weld;
  • versatility - it is possible to conduct research in laboratories and on the spot, without stopping other work and reducing the cost.

Of course, there are a number of disadvantages associated with the complex geometric shapes of the object under study or the heterogeneity of the material. However, this is compensated by the precise technique and experience of the laboratory assistant conducting the ultrasound.

What equipment is used

For ultrasonic testing, flaw detectors are used. These are specialized portable devices that emit and receive ultrasonic waves. Reflecting, the waves fall into the receiver and show the exact location of the damage in the seam on a detailed flaw diagram.

Flaw detectors differ from each other in design, the method of conducting ultrasound, the number of connected sensors, functions and the ability to withstand certain environments.

Scheme of work

Diagnostics of welds in our company meets all the parameters of GOST and is carried out according to the following algorithm:

  • the weld and the part are cleaned from soot, grease, dirt and dust, forming a platform with a side of 5-7 centimeters. Technical oil is applied to the cleaned surface, which improves the contact of the device with materials and increases the accuracy of measurement;
  • the equipment is configured according to the parameters of  state standarts and the object under study, the emitter is installed, while the receiver is held by a specialist;
  • making movements from the back side of the seam, it receives ultrasonic waves, while special software calculates the received electrical signals into a flaw diagram.

For a complete study of the connection, 2-3 sessions of ultrasound are carried out.

The result of the work

Ultrasonic flaw detection requires highly specialized skills and equipment. Therefore, it is worth contacting a laboratory to accurately measure the quality of welds in Moscow. The ECHOPLUS company provides services of ultrasonic testing, thickness measurement, and also sells high-quality flaw detectors at a good price.

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