Emergency Repair of Thermal Pipelines Using Pressure-Resistant Sealing: A Comprehensive Analysis of Technical Application and Engineering Practice In systems such as winter heating in the north, industrial steam transportation, and urban centralized heating, thermal pipelines are responsible for transporting high-temperature and high-pressure media and are important infrastructure for ensuring people's livelihood and production. However, during their long-term operation, thermal pipelines are prone to leakage failures due to corrosion, thermal stress fatigue, and external damage. Thermal pipeline leakage not only causes energy waste but also directly affects heating quality and production safety. Especially during the winter heating period, the shutdown for repair will bring serious social impacts. The pressure-sealing technology, with its unique advantages of no pipeline shutdown, no pressure reduction, and no discharge, has become an ideal choice for thermal pipeline repair. This article will comprehensively analyze the application and practice of pressure-sealing technology in thermal pipeline repair from the characteristics of thermal pipelines, the technical adaptability of pressure-sealing, key equipment, operation procedures, and safety control. I. The Special Nature and Technical Challenges of Emergency Repair of Thermal Pipelines The operating characteristics of the thermal pipeline The medium transported by the thermal pipeline is usually high-temperature steam or hot water, and it has the following notable characteristics: High-temperature operation: The operating temperature of steam pipelines can reach 200℃ - 400℃ or even higher, and hot water pipelines often operate at temperatures above 100℃. High temperatures impose strict requirements on pipeline materials, sealing materials, and welding techniques. High-pressure condition: Thermal pipelines are classified as pressure pipelines, and the operating pressure ranges from a few kilograms to several tens of kilograms. Under the combined high-temperature and high-pressure condition, the risk of leakage is higher and the repair difficulty is greater. Thermal expansion effect: During operation, thermal pipelines experience significant thermal expansion and thermal stress, and the pipelines are in a state of thermal elongation. This characteristic poses special challenges for the installation and sealing of the sealing devices. Insulation layer coverage: The exterior of thermal pipelines is usually covered with an insulation layer and a protective layer. During emergency repairs, the insulation layer needs to be removed, which increases the operation time and complexity. 2. Special Requirements for Emergency Repair of Thermal Pipelines Compared with traditional pipeline repair, the repair of heating pipelines has the following special requirements: The necessity of continuous supply: Especially during the winter heating period, a power outage would lead to a widespread power outage, causing serious issues for people's livelihood and significant economic losses. Pressure-sealing is the key technology for ensuring continuous heating. Protection for high-temperature work: Repair personnel are at risk of being scalded by high temperatures and therefore require specialized protective equipment and operational guidelines. The difficulty of hot-state welding: Performing welding under pressure and temperature conditions requires special welding techniques to prevent welding cracks and burn-through. Requirements for insulation restoration: After the emergency repair is completed, the insulation layer needs to be restored to ensure the thermal efficiency of the pipeline. II. Technical Advantages of Pressure-Resistant Sealing in Thermal Pipeline Emergency Repair Constantly ensure the continuity of heating supply The core advantage of the pressure-sealing technology lies in its ability to complete emergency repairs without interrupting the medium flow. This advantage is particularly crucial for thermal pipelines. During the extremely cold winter, a prolonged power outage could cause a sudden drop in indoor temperature for residents, leading to social problems; for industrial users, a power outage could result in the entire production line coming to a halt. The pressure-sealing technology achieves "operation while repairing" by establishing temporary bypasses or isolated sections, thereby maximizing the continuity of heating supply. 2. Avoid energy loss due to medium emission The medium discharged by the thermal pipeline is high-temperature steam or hot water, which has a high energy value. The traditional emergency repair method requires emptying the medium in the pipeline section, which not only causes energy waste but also poses a risk of scalding from the discharged hot medium. The pressure-bearing sealing technology enables "zero emission" emergency repair, avoiding energy loss and environmental impact. 3. Sealing technology for high-temperature working conditions In response to the high-temperature characteristics of thermal pipelines, the pressure-retaining sealing technology has developed specialized high-temperature-resistant sealing solutions: High-temperature resistant sealing materials: Utilize fluorine rubber, silicone rubber, polytetrafluoroethylene, and graphite composite sealing materials, which can maintain excellent sealing performance within the temperature range of 200℃ - 400℃. Sealed structure: For ultra-high temperature conditions, a metal-to-metal sealing structure is adopted, relying on the thermal expansion characteristics of the metal materials to achieve self-sealing. Cooling protection measures: In the design of the sealing device, a cooling circulation channel is introduced to lower the temperature at the sealing area through water cooling or air cooling, thereby expanding the applicable temperature range of the equipment. 4. Structural design for thermal expansion adaptation The thermal pipelines are in a state of thermal elongation during operation. When designing the pressure-sealing equipment, the thermal expansion factor has been fully taken into account. Axial compensation capability: The stent design has a certain axial expansion and contraction ability, which can adapt to the length changes of the pipeline caused by temperature variations. Flexible connection structure: The connection between the equipment and the pipeline adopts a flexible structure, allowing for certain angle deviations and displacements, avoiding the additional stress caused by rigid connections. Hot-state installation process: Install and weld the equipment while the pipeline is in a hot state, ensuring that the equipment and the pipeline deform in coordination under operating conditions. III. Core equipment for pressure sealing of thermal pipelines High-temperature resistant hole-making machine For hot water pipelines, pressure-bearing hole-making operations require specialized equipment that can withstand high temperatures. Heat-resistant cutting tool materials: Open-hole cutting tools are made of heat-resistant alloy steel or hard alloy, which maintain sufficient hardness and wear resistance under high-temperature conditions.