Pressure-sealing technology: A cutting-edge solution for pipeline maintenance without interruption of flowIn the hidden world of pipeline maintenance, there exists a seemingly impossible technology: during the continuous operation of the pipeline and the splashing of the medium, directly sealing the leakage point. This is the pressure-sealing technology, a technological wonder that combines courage, wisdom and precise engineering. In the energy industries such as petroleum, chemical engineering and gas supply, pipeline transportation is the lifeblood for maintaining production. Traditional pipeline maintenance requires shutdown, emptying and cleaning, which not only causes huge economic losses but also may affect the supply to downstream users. The emergence of the pressure-sealing technology has completely changed this situation. This technology enables the repair, renovation or sealing operations to be carried out directly on the running pipeline without interrupting the flow, safely, economically and efficiently solving the problem of pipeline leakage. Technical principle: Creating stillness in motion Pressure-sealing technology, also known as "Quick Pressure Sealing for Pipeline and Container Without Hot Work or Shutdown", is a technique that prevents the leakage of fluids by cutting off, blocking or isolating the leakage channels while the internal medium of the pipeline or container remains under pressure. The basic principle is to use appropriate sealing components to completely cut off the leakage channels of the medium, or to block or isolate the leakage medium channels, or to increase the fluid flow resistance in the leakage medium channels, so as to form a closed space and achieve the purpose of preventing the fluid from leaking out. The pressure-sealing technology can be mainly classified into the following categories: The injection-type sealing technology is the earliest application of pressure-resistant leak sealing methods. By installing custom fixtures and injecting sealing glue to form a new sealing layer, this method is suitable for leak sealing in straight pipe sections. However, it is ineffective for special areas such as three-way joints, bends, reducers, and root areas of flanges. Mechanical fixation methods include various approaches such as support method, pressure application method, clamp method, and pressure cover method. The appropriate mechanical fixation method should be selected based on the characteristics of the leakage location. For instance, the support method is suitable for larger pipelines that cannot be fixed on the main body; the pressure application method is applicable for sealing leaks such as sand holes and small holes on medium and low-pressure pipelines. The opening and sealing technology is a more complex form of pressure-laden operation. Its full name is "Quick Pressure-Resistant Opening and Sealing without Hot Work or Shutdown". This technology welds or mechanically connects the three-way valve and installs the clamp valve to form a sealed cavity for pressure operation. It uses hydraulic or pneumatic equipment to complete the opening, sealing and pipeline cutting. Double sealing and double blocking is the core process of opening and sealing holes: By installing sealing equipment at both ends of the construction pipe section, the flow of the medium in this pipe section is cut off, and a temporary bypass is set up to allow the medium in the pipeline to continue to be transported. Technological Development: The Journey from Catching Up to Innovation The pressure-sealing leak-stop technology originated in the UK. In the early 1980s, it was first developed in China by units such as Tianjin Petrochemical Company. In 1984, it passed the technical appraisal by China National Petroleum Corporation. This technology filled the domestic gap and thus initiated the rapid development process of pressure-sealing leak-stop technology in our country. In the early stage of domestic development, the injection sealing technology was mainly adopted. Subsequently, various methods such as mechanical fixation, bonding, and freezing were gradually developed. After several decades of development, China's pipeline non-flow sealing and blocking business, based on the introduction of foreign technologies, through scientific research and technological breakthroughs, has achieved independent innovation in multiple technical processes. The sealing equipment has become increasingly sophisticated, the sealing capacity, specifications and types have been continuously improved, and the business scope has also expanded. Nowadays, the sealing diameters range from 25 millimeters to 1020 millimeters, and the maximum sealing pressure can reach 10 megapascals. The application scope has also expanded from the initial petroleum pipelines to various medium pipelines such as natural gas, water, ethylene, gas, and aviation fuel. In recent years, with the continuous advancement of technology, the pressure-sealing technology has witnessed new breakthroughs. The electrically controlled and integrated fishing and plugging device independently developed by Bohai Drilling has been successfully applied in the pressure-sealing operations of oil and gas wells one after another, marking a breakthrough in the technology of pressure-sealing operations. This tool integrates the functions of electric control for plugging and fishing. It can simultaneously achieve precise plugging and efficient setting of the downhole pipe string, filling the domestic gap. In the field of offshore oil and gas production, to address the challenges of large-sized production wellbores in offshore oil fields, the need for high sealing force, and the requirement for bidirectional sealing in some operation measures, a 7″ soluble bidirectional sealing plug was developed, enabling 70 MPa high-pressure sealing of 7″ wellbores. Operation process: Precise and rigorous procedures Pressure-sealing operations are a precise and rigorous systematic project. Every step must be carried out strictly in accordance with the procedures. Taking pipeline pressure-sealing operations as an example, the main processes include: Excavation and sealing operation pit construction When excavating and sealing the operation pit, the construction team leader should uniformly command the excavator, and other personnel should stay away from the site. To prevent the occurrence of landslide during the sealing operation of the pit, there must be a certain slope around the pit. Pressure-sealed welding plug for three-way connection Before welding, a welding process instruction manual should be compiled based on the pipeline material, operating parameters, and the material of the weldment. After welding, a welding process assessment should be conducted according to the welding process instruction manual. Based on the qualified welding process assessment, a welding process procedure should be compiled. During welding, welders must wear protective equipment to avoid eye injuries caused by arc light. Sealed opening Before making the hole, strictly follow the safety operation procedures for pressure testing. If oil leakage occurs during the hole-making process, immediate measures should be taken to identify the leakage point and eliminate it. If the cutting tool gets stuck, immediately move the reversing valve, stop the machine, analyze the cause, and then restart it. Blockade When sealing, follow the principle of "high pressure first, then low pressure; inner side first, then outer side", that is, seal the high-pressure end first, then the low-pressure end. Remove the blockade