The X-ray machines are divided into the units of small (up to 120 kV), medium (200–400 kV), and high (1–2 MV) voltage. The first group of machines is suitable for the study of products from light alloys and thin steel sheets, the second and third groups are used for the flaw detection of massive steel apparatuses.

In most cases, the irradiation is performed with a narrow beam of X-rays. However, there are sectional X-ray tubes specially developed for a circle-wise exposure with an annular field of X-raying.

If a rigorous flaw detection of the products from steel and heavy alloys with the thickness of hundreds of millimeters is required, an electromagnetic betatron radiation is applied. Due to the high energy of betatron radiation (15–30 MeV) and a fine ray focus, it becomes possible to detect flaws with the diameter of 0.8 mm under the thickness of 300 mm at steel products. However, taking into account the cumbersome nature of the equipment, this method is currently used relatively rarely.