Pressure-sealing technology: The "minimally invasive surgery" that safeguards the continuous flow of energy arteriesDeep in the deserts of Xinjiang, within the pipeline of the West-to-East Gas Transmission Project II, high-pressure natural gas is surging at a speed of several meters per second. The pressure line of a valve, which has deformed, urgently needs to be replaced, but the main pipeline cannot be shut down - a precise "minimally invasive surgery on the pipeline" is quietly carried out under a pressure of 7.2 megapascals. Pressure-sealing technology, which is hailed as the "minimally invasive surgery" in the field of pipeline maintenance and repair, is a special technique for modifying, repairing or emergency servicing of operating pipelines without interrupting the flow or releasing the pressure. It achieves this by creating a sealed temporary working chamber on the pipeline to isolate the target section, thereby ensuring the safety of the operation and the continuous operation of the pipeline. With the continuous expansion of the length of long-distance pipeline networks and the increasing operating pressure in our country, this technology has become a crucial means to ensure the safety of energy arteries and achieve a win-win situation of economic benefits and production continuity. 01 Technical Principles and Core Values Pressure-sealing technology, also known as "pressure-sealing technology for pipeline maintenance without hot work or shutdown", is based on a principle similar to the "heart bypass surgery" in medicine: At both ends of the section that needs maintenance, a "window" is made on the pipeline using specialized equipment, and a sealing head is inserted to cut off the flow of the medium. At the same time, a temporary bypass pipeline was established to allow the medium in the pipeline to bypass the construction section and continue to be transported, thereby achieving complete isolation and construction of the specific pipeline section. The value of this technology is multi-dimensional. Economically, it avoids the huge production losses and medium emission costs caused by traditional shutdown operations. In terms of safety, it is carried out in a sealed environment and is flame-free operation, especially suitable for pipelines transporting flammable and explosive media such as oil and natural gas. In terms of environmental protection, it completely eliminates the pollution caused by direct discharge of the medium. In terms of social benefits, it ensures the continuous and stable supply of urban gas, heating, and other essential pipeline networks, and its significance goes far beyond the technical aspect. 02 Comprehensive Analysis of Core Workflows A successful pressure-sealing operation is a complex and meticulous systematic project. Its standard process mainly covers the following eight key stages. Preliminary survey and scheme design This is the cornerstone for the success of the operation. The team needs to precisely grasp the pipeline parameters, including the material, diameter, operating pressure and temperature, as well as the transported medium. At the same time, they need to conduct on-site investigations to determine the location of the operation pit, assess the soil conditions, the surrounding environment and safety risks. Based on these data, they should formulate detailed construction plans, emergency response plans, and complete the necessary administrative approvals. 2. Excavation and Preparation of the Work Pit According to the plan, the excavation operation pits are constructed to provide space for equipment installation and operation. The wall of the pit needs to have a safe slope to prevent slippage. The operation area will be marked with warning signs and equipped with safety facilities such as fire protection and gas detection. 3. Install the blocking elbows and the balancing pipeline This is the key step in establishing the operation foundation. First, the sealing three-way pipe fittings are welded at the selected position. This is the equipment interface for subsequent hole opening and sealing. The welding requirements are extremely high and non-destructive testing must be carried out to ensure absolute reliability. At the same time, the balancing short section and valve are welded and installed to connect the balancing pipe, which is used to balance the pressure during hole opening and sealing, ensuring smooth operation. 4. Sealed opening Install the flange valve and the hole drilling machine on the welded qualified three-way pipe. The flange valve is the key equipment for switching and ensuring the cavity is sealed. Then, conduct a pressure test to verify the sealing performance. After the test is passed, start the hole drilling machine, and the cutting tool penetrates the pipe wall to complete the hole drilling, and then recover the circular pipe wall (piece) that has been cut off. 5. Implement blocking and establish bypasses After the hole is drilled, replace the plug. Lower the plug (such as a cup-shaped, plug-type, or folding type) through the hole into the interior of the pipeline to the predetermined position. Operate the plug to make the plug expand and closely adhere to the inner wall of the pipeline, thereby cutting off the medium. Depending on the engineering requirements, it may be necessary to perform "double sealing and double blocking" at both ends to completely isolate the pipeline section. At the same time, a temporary bypass pipeline can be connected to maintain the full-line transportation. 6. Construction of isolation section After confirming that the sealing is tight, depressurize and replace the gas with an inert gas (such as nitrogen) for the isolated sections to ensure they meet the safety conditions for hot work or construction. Then, the planned maintenance work can be carried out, such as replacing valves, pipe sections, adding branch lines, or repairing leakage points, etc. 7. Removing the Blockade and Restoration After the construction is completed and passes the inspection, operate the plugger in the reverse order, retrieve the plug head. Then use the hole opener to lower the plug to permanently seal the hole, and finally cover with a blind plate. Remove all temporary equipment and close the bypass. 8. Final Inspection and Anti-corrosion Restoration Conduct final inspections on all weld joints and operation points. Restore the original anti-corrosion and insulation layers of the pipeline, backfill the operation pits, and clean up the site. This marks the successful completion of the entire pressure-sealing pr