High-pressure pipeline sealing technology: The security guard protecting the safety of energy arteries Among the complex network of energy arteries, the high-pressure pipeline sealing technology functions as a silent guardian, ensuring the safe and efficient transportation of oil and gas resources. In the modern industrial production and energy transmission fields, pipelines are like the vascular network of the human body, carrying the transportation tasks of important media such as oil and natural gas. And the high-pressure pipeline sealing technology is a special technique for maintaining, renovating and emergency repair of pipelines under the condition of uninterrupted pipeline transportation. This technology not only resolves the problem of having to suspend the pipeline operation for traditional operations, but also significantly enhances the safety and economy of pipeline operation. I. Irreplaceable Function: The Core Value of High-Pressure Pipeline Sealing High-pressure pipeline sealing technology is a safe, economical, rapid and efficient special technology for in-service pipeline maintenance and emergency repairs. It can complete the operations of pipeline replacement, relocation, valve replacement and adding branch lines while the pipeline medium is continuously flowing. It can also quickly and safely repair the accident pipeline and restore its operation when the pipeline leaks. The traditional pipeline maintenance methods require the pipeline to be shut down and emptied, or some temporary remedial measures to be taken. This not only causes huge economic losses but also poses significant risks to the safe operation of the pipeline. Take the Lu Ning pipeline of Sinopec as an example. After adopting the high-low pressure combined blocking technology, the pipeline shutdown time was reduced from the original 24 hours to just 2 hours. Based on the design annual transportation capacity of 20 million tons for the Lu Ning Line, a mere 22-hour difference means an additional transportation of approximately 50,000 tons of crude oil, resulting in considerable economic benefits. II. Technical Principles and Types: Diversified Sealing Solutions High-pressure disc-type blocking technology The technical principle of the pipeline high-pressure disc-type blocking equipment is as follows: First, four split three-way valves (with the two on either side being bypass three-way valves and the two in the middle being blocking three-way valves) are welded onto the operating pipeline. A clamp valve (a special valve) is installed on the three-way valve, and an opening machine is installed on the clamp valve. This way, the opening machine, the sandwich valve, and the three-way valve form a sealed cavity. Then, using the power source (hydraulic or pneumatic), the full-sealed opening process is carried out, and the cut-on-shaped plates are randomly discharged, thus completing the pressure-bearing opening process. After closing the clamp valve, remove the hole-making machine. Then connect the bypass line to the bypass three-way clamp valve and conduct the medium through it, so as to enable the bypass line of the main pipeline to transport the medium simultaneously. At this point, the sealing device is installed onto the sealing three-way clamp valve, and the sealing head is lowered using mechanical means in accordance with the procedures, thereby stopping the flow of the medium in the section of the pipeline that has been modified and repaired. All the medium then flows through the bypass line, achieving the goal of a safe modification and repair. 2. Low-pressure capsule occlusion technique The technical principle of the bag-type pipeline sealing equipment is as follows: At appropriate positions at both ends of the pipe section to be replaced or repaired, two sets of sealing flanges (each set consisting of two, totaling eight) are welded respectively. A pressure-bearing opening is made from the construction point outward in the following sequence: baffle hole, capsule hole, baffle hole, capsule hole. From the downstream holes of each group, plates that can be expanded into a circular shape are sent in, and in the upstream holes, sealed capsules that can be inflated are sent in. The outer surface of the capsule is in close contact with the inner wall of the tube to cut off the oil flow. The rear end of the capsule rests against the plate, and the plate bears the thrust transmitted from the capsule through the sealed capsule due to the pressure of the tube. The inflated sealing capsule is in close contact with the baffle. It uses double-sided double-channel capsules to separate the fluid medium, achieving the purpose of pipeline sealing. This equipment can be operated on pipelines of fluid media such as refined oil, crude oil, natural gas, and water. Its working pressure is 0.5 MPa. 3. Innovative folding-type sealing technology The folding type plugger is a key component of the pressure-resistant non-stop-flow plugging system. The designed folding plugger inserts a folded plug head through a non-uniform diameter hole into the pipeline and fully opens it to temporarily block the flow of the medium within the pipeline. The folding type plug has the advantage of not requiring the drilling of uniform diameter holes, and can seal pipelines of different wall thickness specifications simply by adjusting the positions of the relevant components of the plug head. 4. Overlapping Sealing Technology For the challenges in the renovation of high-drop ultra-high-pressure oil pipelines, the combined sealing technology has provided an innovative solution. The core process involves reasonably dividing a single ultra-high-pressure sealing operation into two or multiple sealing operations, ensuring that the sealing pressure in each operation remains within the range of the high-pressure sealing operation pressure (2.5 - 5 MPa), thereby addressing the risks and safety hazards associated with ultra-high-pressure sealing. The pipeline shutdown combined with blocking construction method not only ensures the construction quality of high-drop ultra-high pressure pipelines, but also shortens the construction time and reduces the construction cost. It provides a reference for similar high-drop ultra-high pressure pipeline renovation construction. III. Implementation Process: Step-by-step meticulous operation The implementation of high-pressure pipeline sealing operations must strictly follow professional procedures: Preparatory work and excavation of the operation pit 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. 2. Pressure-sealed welding plug for three-way junction During welding, the oil pressure in the pipeline must be reduced to below 2.0 MPa, and cooling measures such as water cooling must be taken. During the welding process, welders must wear protective equipment to avoid eye injuries caused by arc light. 3. 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. 4. Blocking operation 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.