Applied Insulating Coatings for Gas Distribution Pipelines in the Republic of Belarus and Their Characteristics

Gas distribution system is a production complex, which is part of the gas supply system and consists of organizational and economically interconnected facilities designed to organize the supply of gas directly to consumers. On the national basis of the gas distribution system is formed by about 67.0 thousand km of external distribution gas pipelines, 28.0 thousand km  of which are underground steel pipelines. As potentially hazardous objects, steel underground distribution pipelines are subject to higher requirements for corrosion protection. As a rule, they are provided with complex anticorrosion protection, an obligatory component of which is insulation coatings. Taking into account the above mentioned, the definition of general indicators characterizing condition of insulation, the degree of its wear is an actual task. To solve it, for the first time, we have analyzed an array of long-term statistical data on defects of protective coatings of distribution gas pipelines, detected by instrumental method. The values of specific defect density Dd and damageability Ad have been determined for all types of applied protective coatings. The best values have been found for insulation on the basis of heat-shrinkable tapes. The characteristic damage of  the protective coating on the basis of bituminous mastics (microcracks), which can be used as an indicator of aging of this type of insulation, has been determined. It has been shown that defect formation in the insulation coatings of gas pipelines up to the present time is, as a rule, a low-intensive process, which has been confirmed, among other things, for  gas pipelines operated for a long time. The obtained results were included into the justification of abolition of the previously used 40-year normative service life of steel gas pipelines in the new edition of the Rules of Technical Safety in the Field of Gas Supply of the Republic of Belarus.