As the government and society pay increased attention to public security issues, people's living standards are improving day by day, and the requirements for the safety and reliability of gas pipeline gas supply are becoming higher and higher. Because this technology can reduce the pollution of residual gas to the atmospheric environment and effectively save gas energy, it can carry out construction operations such as maintenance and renewal of medium and low pressure pipelines in various cities without stopping transmission, and can maintain a safe and normal supply of gas during construction. In densely populated urban areas, it has outstanding environmental protection, energy conservation and safety, and fully conforms to the current national energy utilization policies for energy conservation and consumption reduction. Therefore, the non-stop gas pipeline construction technology plays a positive role in the sustainable development of the city and the stability and harmony of society. It has become an emerging field in the development of gas pipeline construction technology, and the market demand is increasing day by day. The core key of this topic is to study various plugging forms of medium and low pressure non-stop transportation construction technologies and analyze their technological characteristics; focus on research on bladder plugging technology to ensure the tightness of the plugging effect during non-stop transportation construction. Sex, so that subsequent plugging construction can be carried out in a safe and reliable state; analyze and study the material properties of the plugging air bag in bladder non-stop transportation, and study and design the connection method between bladder non-stop transportation pipes and the pipeline to be plugged; Comprehensive analysis and comparison are carried out on various types of non-stop transportation plugging forms to determine the application scope of various types of medium and low pressure non-stop transportation construction technologies and form a standardized medium and low pressure non-stop transportation technical system. This topic is the first time that the domestic gas industry has conducted research on the non-stop transmission construction technology of medium and low pressure gas pipelines. It compares and analyzes the non-stop transmission construction technology of various medium and low pressure gas pipelines such as barrel sealing, pipeline blocker sealing, and bladder sealing, summarizes the basis for selecting non-stop transmission technology according to different conditions, and finally determines the application scope and applicable pressure level system of various non-stop transmission construction technologies. The compiled "Construction Method for Bag-Type Non-stop Transmission and Blocking of Urban Medium and Low Pressure Gas Metal Pipelines" has been rated as a Shanghai City Municipal Construction Method, and the Shanghai City Municipal Standard "Technical Specifications for Non-stop Transmission Engineering of Urban Gas Pipeline" is in the process of preparation, providing high reference value for future project implementation. The independently developed "Gas Pipeline Bladder Blocking and Non-stop Transportation Construction Technology and Its Special Clamp Ties" has been authorized by the national invention patent, and the "Special Clamp Ties for Gas Cast Iron Pipe Bladder Blocking and Non-stop Transportation Construction" has been authorized by the national utility model patent.,"Gas Pipeline Bleeding System" and "Air-blocking Air Bag Inflation and Deflation Device for Gas Pipeline Inlaying" have been authorized by the utility model patent, of which the application for the invention patent of "Gas Pipeline Bleeding System" has been accepted. In order to realize the connection between steel equipment and cast iron pipes, and at the same time ensure the overall physical properties of the pipes to meet the sealing requirements during construction, in this project, the design and research and development of special pipe fittings solves the problem that cast iron pipes in the domestic gas industry cannot achieve bag-type non-stop transportation construction. The technical problem of transportation construction fills the relevant domestic technical gaps. As a test and practice of the subject, a number of non-stop transmission transformation tasks of capsule medium and low pressure pipelines have been completed in Hongqiao Junction, Wusong Gas Factory, Fengxian Jianghai Road and other areas, and have all been successful and well received by all parties. In the non-stop construction of urban medium and low pressure gas pipelines, as a construction technical means for non-stop transmission transformation and maintenance and emergency repair of gas pipelines, the non-stop transmission technology of medium and low pressure gas pipelines has broad application prospects. It can not only be applied to pipeline rerouting operations, but also can be promoted and applied to emergency repair of gas pipe networks. Among them, the non-stop transmission construction technology of the bladder type medium and low pressure gas pipeline is characterized by simple operation, strong practicality, environmental protection, energy saving, safety and reliability. It is especially suitable for large-diameter urban gas medium and low pressure metal pipelines, and has good social benefits and economic benefits.