The journey of pressure-sealing technology research and development: A leap from introduction and digestion to independent innovation In the field of industrial pipeline maintenance and emergency repair, the pressure-sealing technology is hailed as the "scalpel for the energy arteries" - it can complete tasks such as leakage control, pipeline section replacement, and branch connection while keeping the pipeline in a normal operating state and ensuring the continuous flow of the medium. This specialized technology, which originated in the 1960s, has undergone decades of research and iteration and has become a core equipment for ensuring the safe operation of fields such as petroleum, chemical industry, and urban gas. This article will systematically review the development history of the pressure-sealing technology and showcase China's leapfrog development from technology introduction to independent innovation in this field. I. Technological Origin: The Birth and Early Exploration of Pressure-Resistant Sealing The pressure-sealing technology originated in the UK. Its basic principle is to establish a new sealing structure at the leakage point by injecting sealing agent or installing special sealing devices while the equipment or pipeline is under operating pressure. The core value of this technology lies in "no shutdown" - it neither disrupts the normal transportation of the pipeline nor hinders the safe and efficient completion of maintenance operations. In the early 1980s, China began to come into contact with this advanced technology. In 1980, the article "Sealing Technology for Equipment and Pipeline Leakage" was published in China, systematically expounding the non-stop and pressurized sealing technology for the first time, marking the beginning of the research and application of this technology in China. Subsequently, units such as Tianjin Petrochemical Company took the lead in conducting independent research and development. After several years of hard work, in 1984, this technology passed the technical appraisal by the China Petroleum and Chemical Corporation, filling the domestic gap. The early research and development focused on the injection-type sealing technology. This method involves installing specially designed fixtures at the leakage site to form a sealing chamber. Then, a high-pressure injection tool is used to inject the specific sealant into the chamber, allowing the sealant's pressure to balance with the pressure of the leakage medium, thereby establishing a new sealing structure. Although this process solved some leakage problems, it was mainly applicable to straight pipe sections and was ineffective for complex parts such as elbows, bends, and reducers. II. Formation of the technical system: Breakthroughs in the research and development of seven major categories of methods As the research and development progressed, China gradually established a complete pressure-sealing technology system. According to industry data, our country has successively developed seven types of methods including steel tape tensioning technology, rapid binding technology, low-pressure patching technology, injection sealing technology, rapid anti-theft technology, plug welding technology, and pipeline pressure repair technology. There have been over 30,000 successful application cases. The research and development of the steel belt tensioning technology is targeted at medium and low pressure leakage scenarios. The traditional clamp sealing method has long pre-assembly time and poor on-site adaptability. The research team, through innovative structural design, developed a series of products such as composite plugging devices and formed steel belt plugging devices. In 2003, at the small-jie joint station of the No.3 oil production plant of Dagang Oilfield, the weld seam of the outlet pipeline elbow of the settling tank leaked. The medium was a mixture of oil, gas and water, with a pressure of 1.2 MPa. Using the steel belt tensioning process, the leak was successfully plugged in 20 minutes, verifying the reliability of this technology. The breakthrough of the rapid binding technology lies in integrating the holding and sealing functions into one. As the thickness of the binding tape increases, it can continuously generate pressure, thereby achieving the purpose of rapid binding and leak sealing. In 2004, at the H106-6 station of Xinhai Oilfield Shuichang Oil Production Plant, the composite pipe at the outlet leaked. Using this technology, the leak was successfully sealed within 30 minutes. The low-pressure patching technology has solved the problem that adhesives are difficult to be directly patched under pressure. The R&D team innovatively designed the "flow-directing cap" patented product, achieving chemical bonding under pressure conditions. In 2004, at the No. 1 tank of the Shihao 100 water injection station in Shengli Oilfield, there was a leakage at the bottom. Using the low-pressure patching technique, the leak was successfully blocked in just 30 minutes. The research focus of the injection-type sealing technology lies in high-pressure conditions. For leakage above 2-3 megapascals and difficult positions such as flanges and valves, the research team has developed a patented product for high-pressure sealing injection. It can cover various leakage scenarios of different pressure levels (below 35 MPa) and different leakage positions. In 2004, the sealing head flange of the heat exchanger on the Dongfang platform of China National Offshore Oil Corporation in Zhanjiang suffered leakage. The medium was natural gas and the pressure was 6 MPa. Using this new technology, the leakage was successfully sealed within 20 hours, avoiding the shutdown of the entire gas field and the downstream fertilizer plant. The emergence of rapid anti-theft technology was driven by specific needs. In response to the problem of criminals installing valves to steal oil and gas in the oil and gas pipelines, the research team developed the patented product of the expansion-type plug, which enabled the safe removal of the stolen oil and gas valves without interrupting production and restored the pipeline to its original state. In 2003, the external transmission trunk line of the No. 11 metering station of Zhongyuan Oilfield Production No. 3 Plant was equipped with a gas theft valve. Using this technology, the valve was removed in 20 minutes and successfully sealed. The innovation of plug welding technology lies in addressing the safety hazards of electric welding repairs. The traditional method of inserting wooden plugs followed by electric welding has significant safety risks. The research team developed a pipeline plug sealing tool combined with a high-temperature sealing pad, which can perform welding while successfully sealing the leak, significantly reducing safety risks. In 2003, the gas pipeline transmission main line in the Liaocheng section of Shandong Natural Gas Pipeline Co., Ltd. suffered severe leakage due to external damage from an excavator. Using the plug welding technique, the leak was successfully plugged under pressure within 90 minutes. The concept of pipeline pressure-retaining repair technology is more forward-looking - it involves rebuilding a new pipeline on the original one. By installing prefabricated mold pipes on the pipeline to be repaired, and using a pressurization process to inject epoxy resin into the interlayer between the mold pipe and the pipeline for curing to form a new pipeline, the technology enables non-stop and pressure-retaining repair. In 2006, a serious leakage occurred in the liquid phase discharge pipe of the de-butane treatment plant at the Longkou Binhuan Terminal of China National Offshore Oil Corporation. The problem was successfully resolved within two hours using the mold pipe forming process. III. Independent Innovation of Core Equipment: From Laggard to Paralleler Based on the formation of the seven major technical systems, the research and development focus gradually shifted to independent innovation of core equipment. The research and development of pipeline pressure-sealing technology equipment went through an evolution process from imitation to independent research and development, and from single machines to system integration. The innovation breakthrough of the drilling machine is a key aspect. Traditional drilling machines have problems such as insufficient redundancy in the balance system and low drilling reliability. The R&D team increased two sets of high-pressure balancing devices, which enhanced the redundancy of the drilling machine's balance system. Even if one set of the balance system fails, it can switch to the other immediately to ensure high drilling reliability. In response to the cutting challenges posed by high-strength pipeline steels like X80, the drilling tool uses high-strength hard alloy materials, special angle design, and optimized tooth structure to ensure smooth drilling without the need for welding anti-expansion rings. The application of the welding process used in the military armored infantry combat vehicle ensures that the tooth teeth will not experience tooth loss due to welding quality. The innovation in the sealing technology of the plug also achieved a breakthrough. The traditional lip-edge sealing method was abandoned, and the multi-line sealed rubber bowl design solved the problem of difficult sealing under high and low pressure conditions of the pipeline. Through the optimization of the sealing head and the rubber bowl structure by fluid dynamics simulation (CFD), the sealing performance reached the theoretical optimum. The accompanying developed cleaning device can push the iron filings away, avoiding damage to the rubber bowl - traditionally, using old rubber bowls for cleaning was difficult to push the iron filings far away, and it would still cause damage to the sealing rubber bowl. The structural change of the sealing components has eliminated the potential leakage problem in the later stage. The traditional process adopted a "locking pin" or "external clamp" structure, which was prone to leakage during subsequent operation. The new type of sealing components changed from the "external clamp" structure to the "internal clamp" structure. By using a transmission mechanism, the clamp plate extends internally and securely positions itself, without the need for locking pins or locking rings, thus eliminating the leakage隐患 caused by the failure of the sealing ring in the later stage.