Pipeline Steels Strain Behaviour in High Mineralized Soils

• Main Author: A.I. Stanetsky
• Format: Article
• Language: English
• Published: Ukrainian National Forestry University 2017-02-01
• Series: Науковий вісник НЛТУ України
• Subjects: pipelines; safe operation; emergency situations; deformation behaviour
• Online Access: https://nv.nltu.edu.ua/index.php/journal/article/view/193
• ISSN: 1994-7836; 2519-2477

The study of the features of corrosion degradation of the linear material underground pipelines in soils of different types is important to ensure the safe operation of gas pipelines and forecasting of resource (residual life) work correctly assesses operational risks. Our research aims at studying of long-acting and highly acidic medium term work on the deformation behaviour of the material pipelines. We have chosen main gas pipelines of large diameter made of steel 17HS that have been in operation for over 40 years as the object of the study. Test samples of pipelines material for air and liquid environments performed in static mode and re-load static pure bending with automatic registration trough design. To study the kinetics of deformation based on the results of previous studies and to improve their comparative analysis, we selected a similar level of nominal voltages that are 330, 420 and 510 MPa. In addition, in ME1, The pH of which is equal to 5, witnessing growth of strain from 5 to 15 percent, depending on the nominal stress fix and increase the angle of inclination of the final section of the curve, which indicates the danger of further loss of material's ability to resist prolonged stress. In the decreasing pH to 4 (ME2) fix significant deformation jumps occurred. Long term exploited steel deformation behavior in ME3 at pH 3 is more predictable. Cycles acceleration-deceleration strain are present, but their rate is lower than ME2. Furthermore, giving the significant aggressive environment, it is easy to predict significant risks due to rapid decompression of the metal in areas of damaged coating. Thus, the results of the research indicate significant risks of emergency situations in highly acidic soils, especially with simultaneous maintenance of chlorides and sulphates. This problem requires further investigation by physical simulation of processes of interaction of pipelines with soil electrolyte. Special attention should be paid to optimization of corrosion protection, including the value of the protective potential of cathodic stations.