The article describes the methods of improving the durability of new gas pipelines, as well as examines the need of rising the level of inspection security. Reliable gas pipelines is an important safety indicator of people's housing areas and the industrial and commercial organizations work areas. The verification of durability and tightness of gas pipelines is one of the most important inspection, which shows the existence of defects in compliance of the gas pipelines and debt construction technologies and instructions. Detected on time defects influence the number of uncontrolled natural gas leaks in the pipelines. When assessing the impact of hidden defects on the durability and reliability of the gas pipeline, the gas pipeline monitoring process was made, and the defects in the construction of gas pipelines (polyethylene, steel) and fittings were more often detected, the effect of hidden defects of gas pipelines on the safety of pipelines was analyzed. The experiments described in the article were carried out to evaluate the durability and tightness of gas pipelines by simulating the hidden defects on new installed gas pipeline in two sites: Site 1 and Site 2, both places are situated in Latvia. The obtained data was processed and reflected in tables, charts, graphs, and the results were analyzed and summarized in the conclusions, and also proposals are made to improve the problem. In the article is described a calculation methodology, which proves what needs to be improved in order to increase the safety of newly built and reconstructed gas pipelines.