PSI - Issue 59

V. Makarenko et al. / Procedia Structural Integrity 59 (2024) 385–390 V. Makarenko et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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sites (A-B) and (D-E), it increases by 2.4 times. As for the oxygen content in the surface layers of corrosive products taken from the surface of pipelines with different service life, its maximum concentration in corrosion products in the section (B-C-D) increases 1.7 times with an increase in the service life of pipes from 10 to 40 years, and compared with the same in the sections (Α -B) and (D-E) for similar service life of sewer structures – by 2.2 times. The results of microhardness and hydrogen content measurements in the wall section of pipes of various grades and service life are shown in Table 1.

Fig. 1. Distribution of residual concentrations of hydrogen (a), sulfur (b) and oxygen (c) in the metal of pipelines operated for a long time at sewage facilities: 1 – 10 years, 2 – 20 years, 3 – 30 years, 4 – 40 years. The material of the pipe walls is steel 09G2S.

Table 1. Hydrogen content and microhardness of metal of pipe steels with different service periods. Steel grade Term of operation [H], ppm H μ  10 7 , Pa

10 20 30 40 10 20 30 40 10 20 30 40

5.5 9.7

58 70

09G2S

12.5 16.7

120.5

155

17G1S

6.0 9.5

55 68 82

11.7 17.5

125

20

6.2

65 84

10.5 14.6 18.8

115 163