Research and development of pressure-sealing technology for pipelines: Technological evolution, innovative breakthroughs and future prospects In the industrial fields such as oil and gas pipelines, urban water supply networks, and chemical plants, the safe operation of pipelines is crucial for ensuring energy supply and public safety. However, during their long-term operation, pipelines inevitably encounter the needs for maintenance, renovation, and emergency repairs. The traditional methods require pipeline shutdown operations, which not only cause huge economic losses but also bring environmental risks due to the emission of media. The research and application of pipeline pressure-sealing technology have completely changed this situation - it enables the isolation and repair of pipelines without interrupting the medium supply, becoming an important supporting technology for pipeline integrity management. This article will systematically review and look forward to the research history and development trends of pipeline pressure-sealing technology from multiple dimensions such as research background, technological evolution, core breakthroughs, innovative achievements, and future directions. I. Research Background: From Passive Response to Active Technological攻关 Driven by actual needs The research and development of pipeline pressure-sealing technology is based on the practical needs of industrial development. With the rapid growth of industries such as petroleum, natural gas, chemical engineering, and urban heating, the pipeline network has become increasingly large and complex. During the operation of these pipelines, maintenance demands continuously arise due to corrosion, external force damage, and material aging. The direct economic losses and indirect social impacts caused by pipeline shutdown for maintenance have become increasingly prominent - a day of pipeline shutdown in a refining and chemical enterprise may result in losses of several hundred million yuan, and the shutdown of urban gas pipelines will affect the normal lives of thousands of households. The urgent need in reality calls for a technology that can isolate and repair the pipeline without interrupting the transportation. 2. Promotion of Safety and Environmental Protection Apart from economic factors, safety and environmental protection requirements are also significant driving forces for the development of pressure sealing technology. During shutdown maintenance, it is necessary to empty and replace the medium, which not only leads to resource waste but also may cause pollution to the environment. For flammable and explosive media, the process of emptying and replacing itself inherently poses safety risks. The pressure sealing technology has achieved an operation mode of "no shutdown, no discharge, and no pressure reduction", fundamentally eliminating these safety and environmental risks, and conforming to the concepts of green development and safe development. 3. Conditions for Technological Development The development of pressure-sealing technology also benefits from the progress of related basic industries. The emergence of high-strength and high-toughness sealing materials, the maturity of hydraulic control technology, and the improvement of precision mechanical processing capabilities have provided technical support for the research and development of pressure-sealing equipment. At the same time, with the continuous increase in pipeline operating pressure and the increasingly complex types of media, developing pressure-sealing technologies with higher pressure ratings and broader adaptability has become an inevitable choice. II. Technological Evolution: The Development Process from Simplicity to Completeness The early exploration stage The research and development of pipeline pressure-sealing technology can be traced back to the early 20th century. In the early days, pressure-sealing mainly relied on simple fixtures and mechanical compression methods, and was used for temporary handling of local leaks. These methods were easy to operate, but had low sealing reliability and were limited in application scope, being only suitable for simple leaks in low-pressure and small-diameter pipelines. The research focus during this stage was to address the issue of "whether it can be sealed". The researchers tested various sealing materials and structural forms, and explored the adaptability to different media. Although the technology was not yet mature, it laid the foundation for the subsequent systematic research. 2. Systematic Research and Development Phase In the mid-to-late 20th century, with the rapid development of the petrochemical industry and urban gas sector, the technology of pressure-sealing and blocking entered the stage of systematic research and development. The main feature of this stage was the formation of a complete technical system and equipment series. Core equipment such as hole-opening machines, clamp valves, and blocking devices were designed and manufactured in a specialized manner, forming a complete product line ranging from DN50 to above DN1000. The focus of the research and development work shifted to addressing the issue of "how to reliably seal". In terms of sealing structures, various technical routes such as cylindrical sealing, folding sealing, and capsule sealing are developing concurrently, each with its own emphasis; in terms of opening techniques, mechanical opening and pressure balance technologies are constantly improving, significantly enhancing the opening accuracy and safety; in terms of materials, sealing materials with high temperature resistance, corrosion resistance, and aging resistance have been widely applied. 3. The stage of intelligence and refinement Entering the 21st century, the research and development of pressure-sealing technology has entered an intelligent and refined stage. The characteristics of this stage include the wide application of digital design, automatic control, and intelligent monitoring technologies. The R&D personnel utilized simulation methods such as finite element analysis to precisely simulate the force state of the occluder and the deformation behavior of the sealing elements, thereby optimizing the structural design. They adopted servo control technology to achieve precise control of the opening process. They developed a remote monitoring system to monitor the sealing status in real time and promptly detect abnormalities. They introduced precise detection technologies such as laser measurement and three-dimensional scanning to improve the accuracy of opening positioning and the installation of the occluder. Meanwhile, specialized technologies tailored for specific working conditions have been constantly emerging. Technologies such as high-pressure sealing technology, high-temperature sealing technology, underwater pipeline sealing technology, and gas pipeline non-stop-flow sealing technology have expanded the application scope of pressure-bearing sealing technology. III. Key Technical Challenges and Breakthroughs in the Research Process Sealing technology challenge Sealing is the core of pressure sealing and also the most difficult technical challenge. There are irregular factors such as ellipticity, weld bead height, corrosion pits, and deposits on the inner wall of the pipeline, which impose extremely high requirements on the adaptability of the sealing elements. When the sealing elements need to maintain reliable sealing performance in a high-pressure medium for a long time, strict requirements are imposed on the materials' resistance to creep, aging, and medium resistance. The breakthroughs in research and development are manifested in several aspects: in terms of materials, from ordinary rubber to fluorine rubber, perfluoroether rubber, polytetrafluoroethylene and other high-performance sealing materials have been developed;