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WELDING TECHNOLOGIES
AND EQUIPMENT
Tanks for storing liquids, vessels and with a thickness of 10-200 mm, aluminum
pipelines operating under excessive pressure, up to 300 mm, copper up to 25 mm. At the
by hydraulic and pneumatic loading, using leak same time, defects are fixed, the dimensions
detectors and kerosene are tested for density. of which are 2% of the thickness of the
Magnetic control is based on the magnetization metal.
of welded joints and the detection of magnetic
scattering fields in defective areas (Fig. 2).
When controlling the quality of welding
with magnetic flaw detectors, the phenomenon
of electromagnetism is used. The device creates
a magnetic field around the studied area, the
stream of lines of which, passing through the
metal, bends at the places of defects. This
distortion is fixed in certain ways, of which two
are used in the welding industry - magnetic

Fig. 3. Quality control of welds with magnetic flaw
detection: 1 - magnet, 2 - weld, 3 - defect, 4 - magnetic
film.

Fig. 2 Quality control of welds with magnetic flaw detection

particle and magnetographic. In the first case,
a dry or wet (mixed with oil, kerosene or soapy
solution) ferromagnetic powder (for example,
iron) is applied to the surface of the welded
joint, which accumulates in the places of defects,
thus indicating the presence of discontinuities. A
more advanced magnetographic method involves
applying a ferromagnetic tape to the seam, on
which existing defects appear after passing it
through the device (Fig. 3).
Only ferromagnetic metals can be
subjected to magnetic control methods. Nickel
chromium steels, aluminum, copper, which are
not ferromagnets, are not subject to magnetic
control. Fig. 4. Identification of defects in welds
X-ray diffraction is based on various
absorption of X-ray radiation by metal sections
with and without defects. Welded joints are
translucent using special x-ray machines. After
the film develops, areas of increased darkening Transmission with gamma rays (Fig. 5)
are fixed on it, which correspond to defective compared with x-rays has several advantages.
places in the welded joint. The type and size of Due to the portability of the equipment, it
defects is determined by comparing the film with can be used in any conditions (in workshops,
reference images (Fig. 4). field conditions, at installation, etc.). In
X-ray machines used in industry make it addition, gamma ray transmissions are a
possible to shine through welded joints of steel less expensive method.

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