POLYETHYLENE GAS PIPELINES: PROBLEMS AND EXPERIENCE OF TECHNICAL DIAGNOSTICS

More and more often in various industries, polymer materials are replacing metal structures. The gas industry is no exception, one of the areas of development of which was the introduction of polyethylene pipes to replace traditional steel pipes. This process began more than half a century ago, and according to data at the beginning of 2023, polyethylene pipes account for about 49.5 % of the length of all underground gas pipelines of gas distribution networks. The main obvious advantage of polyethylene pipes over steel pipes is corrosion resistance, which allows them to be operated without the use of protective anticorrosive coatings and electrochemical protection means. The strength properties of polyethylene pipes allow their operation at gas pressure up to 1.2 MPa, which makes it possible to almost fully meet the needs of the gas distribution sphere. The welding technologies of polyethylene pipes are well developed, standardized and automated. An important problem for long-term operating polyethylene gas pipelines is the assessment of their technical condition and determination of the residual life. Despite the existing need for work of this kind (for example, in 2022 only in the territory of the Saratov region it was required to carry out technical diagnostics of 8 gas pipelines with a total length of 39.86 km), expert organizations do not have the necessary tool for implementing this task today. Although the mechanism of aging of polyethylene is well known, there are no generally accepted standards for assessing the performance of polyethylene gas pipelines based on a comprehensive accounting of the influence of aging factors that determine their technical condition. The purpose of this article is to highlight the experience of Giproniigaz JSC in technical diagnostics of polyethylene gas pipelines, as well as to draw the attention of specialists from both the gas industry and academic science to the problem of developing a methodology for technical diagnostics of polyethylene gas pipelines.