Within the framework of the present Thesis, a methodology for assessment of the technical condition of distribution gas pipeline systems suitable for the Latvian conditions was developed. Within the present Thesis the structuring of the technical operational process of distribution gas systems was carried out, the methodology for assessment of the technical condition of distribution gas pipeline systems was developed and tested at Bauska and Cēsis divisions of the Joint Stock Company (hereinafter JSC) "Latvijas Gāze". The Thesis also contain elaborated unified methodologies for performing technical diagnostics (stray current, electrical protection, soil specific resistance measurements, insulation defects and adhesion, operational conditions of steel underground gas pipelines, etc.) and uniform forms for recording the above measurement results. There is comparative assessment and recommendations for selecting equipment and measuring devices used for technical diagnostics of gas pipelines and their testing. The data obtained in various regions of Latvia in the result of the research allow concluding that certain "risk areas" get formed in distribution gas pipeline systems and their condition can be assessed and measures can be implemented for minimising the risk of accidents. The operational risk analysis of a gas pipeline contained in the methodology developed within the Thesis present a constituent of the industrial safety management and provides for a systematic use of all the available information for identification of danger and assessment of the risk of undesirable events. In the course of the research the optimum values of the calculation were identified and necessary formulae for calculation and the criterion for assessment of the results was provided, i.e. the operational risk (Re) may not exceed the admissible risk (Rp). Implementation of the methodology for assessment of the technical condition of distribution gas pipeline systems as developed within the Thesis and its inclusion in regulatory documents will ensure justified and operative assessment of the technical condition of gas pipelines. The results of the Thesis were reported at 8 international conferences and reflected in 8 publications.