Continuous pressure sealing and plugging: The "minimally invasive surgery" operation for the "artery of energy" explained in detailIn 2022, on the Xinjiang section of the national energy artery "West-to-East Gas Transmission Line II", a bypass pressure line adjacent to a pipeline with a running pressure of up to 7.2 megapascals suffered severe deformation. The maintenance team faced a severe challenge: How to safely replace this faulty section of the pipeline while ensuring no interruption of natural gas supply to several eastern provinces and cities, and without releasing the highly pressurized and flammable gas inside the pipeline? The answer was a technology known as "minimally invasive pipeline surgery" - a pressure-remained pipeline sealing technology without pipeline shutdown. Pipelines are the veins of modern industrial society, continuously transporting energy and materials. Traditional pipeline maintenance is like a "coronary surgery", requiring the complete shutdown of the pipeline and the complete removal of the medium, resulting in huge economic losses and safety risks. The non-stop pressure-sealing technology without pipeline shutdown completely changes this model. It allows engineers to safely complete isolation, repair or renovation operations while keeping the pipeline at full pressure and the medium flowing continuously. This technology integrates precision machinery, materials science and fluid dynamics. The standardized operation procedures serve as the lifeline ensuring absolute safety and success in the operation. Next, we will delve into this rigorous process that is comparable to a surgical procedure. Step 1: Surgical planning and preoperative preparation Any successful surgery begins with thorough diagnosis and planning, and the same is true for pressure-sealing operations. This stage sets the foundation for all subsequent work. Core tasks: On-site investigation and technical plan formulation The team needs to precisely measure the material, outer diameter, wall thickness, operating pressure and medium characteristics of the target pipe section. At the same time, they need to assess the excavation conditions of the operation pit, the surrounding environmental risks, and utilize historical data from pipe internal inspections, etc., to avoid areas with severe corrosion or dense welds. Based on these data, engineers will formulate detailed construction plans, clearly define the sealing points and welding points, and complete all necessary approval procedures for work permits. Key Control Points: · Precise positioning: The sealing points must be avoided from areas where pipeline welds exist or where stress concentrations may occur. · Wall thickness verification: Using ultrasonic thickness measurement, ensure that the wall thickness at the welding point meets the safety requirements. · Emergency Plan: Develop comprehensive emergency response measures to address potential risks such as medium leakage and fire. Step 2: Establishing the surgical access - Welding and Installation This stage involves establishing a safe and sealed "operating cabin" on the running pipeline. Core task: Welding specially made pipe fittings and installing valves Pipeline pre-treatment: Remove the anti-corrosion coating from the pipeline surface until it reveals the metallic luster. 2. Welding and sealing the three-way connector: At the designated position, weld the specially designed "sealing three-way connector". This is the foundation for subsequent hole drilling and sealing. The welding quality must be extremely high, and 100% non-destructive testing (such as radiographic testing) is required. 3. Install the critical valve: Install the clamp valve on the blockage tee. This valve is similar to the sealing door of a surgical cabin. It will play a crucial role in isolating the high-pressure medium inside the pipeline from the external environment before and after the opening. Key Control Points: · Welding process: The approved welding techniques are employed, and they are carried out by certified welders to ensure the weld strength is completely reliable. · Ellipticity control: Before welding, the ellipticity of the pipeline needs to be measured and ensured to be no more than 1% to prevent poor sealing. Step 3: Perform the core operation - Pressure-Resistant Hole Opening This was the first crucial operation carried out in the "operating chamber", with the aim of creating a temporary passage on the main pipeline. Core task: Cutting the pipeline in a confined space Connect the hole-making machine: Securely install the hole-making machine on the clamp valve. 2. Pressure Detection and Balance: Conduct a pressure sealing test on the entire connection system (opening machine, valves, three-way valves) to ensure there is no leakage. Subsequently, use the balancing pipe to equalize the pressure inside the opening machine chamber with the pressure in the pipeline. 3. Start the opening operation: In a state of pressure balance, start the opening machine. The cutting tool extends from the clamp valve and penetrates the wall of the main pipeline, cutting off a complete circular section of the pipe wall (referred to as a "piece of material"). 4. Safe Retrieval: After the hole is drilled, the cutting tool holds the "piece of material" and retreats back into the cavity of the drilling machine. Immediately after that, the clamp valve is closed. At this point, a through-hole has been formed on the pipe, but it is safely isolated by the valve. Step 4: Implement sealing and isolation - Insert the sealing cap This is the crucial step to achieve "no leakage", with the aim of establishing a temporary isolation barrier within the pipeline. Core task: Insert the plug to isolate the medium. 1. Replace the equipment: Remove the hole-making machine and install the plugger onto the clamp valve. 2. Lower the sealing head: Open the clamp valve and lower the sealing head (a device with a sealing component) of the sealing device through the opening into the predetermined position inside the pipeline. 3. Expansion Seal: Operate the blocking device to cause the sealing elements on the blocking head (such as rubber sacs or folding umbrella plates) to expand and tightly adhere to the inner wall of the pipeline, thereby completely isolating the pipe section to be operated from the media flowing upstream and downstream.