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In the article on the basis of mechanical, metallographic and X-ray spectral studies, the cause of accidental destruction of CHP pipelines is established. Metallurgical investigations have established that the surface of the pipelines is affected by corrosive ulcers, characteristic of products of corrosive influence of the chemically active process medium, pumped by pipelines. It is shown that corrosion of metal pipes of pipelines is accompanied by its active flooding and venting, which results in decrease of plastic properties and stability of the material against corrosion-mechanical destruction of pipelines, especially after 3-5 years of operation. Concentric distribution of elements on separate sections of corrosive impressions of pipe walls was studied using secondary ion mass spectrometry. Metallographic studies found that the surface of the pipelines was affected by corrosive ulcers, characteristic of products of corrosive influence of the chemically active process medium, which is pumped by pipelines. The scan was done horizontally, in the middle part of each plot. The construction of the distribution curves of the alloying elements present in the steel, in particular chromium, was performed to clarify the boundaries of these defects. In the cavities of the ulcers, the maxima of carbon concentrations and the oxygen distribution similar to it are recorded, indicating carbon-carbon corrosion of the metal in the presence of chemically aggressive technological environments. Microhardness was determined according to GOST 9450-80 using a diamond pyramid together with a metallographic microscope. Samples for hardness measurements were prepared in the same way as macrosplights. The change in the level of stresses of steel steels with different operating life was determined on standard cylindrical specimens with a diameter of 5 mm, which were cut from the blanks of these steels, and subjected to uniaxial stretching type MI-12 [6]. [ABSTRACT FROM AUTHOR]