Pipe opening for connecting branch pipes: What seems simple is actually a demonstration of professional skillsOn a running water supply pipeline, the workers carefully connected the drilling machine to the surface of the pipe. As the machine roared, hot iron filings slowly spilled out from the cutting edge of the pipe - this was a construction process that combined risks and skills. Pipe opening and branch connection is an indispensable key technology in modern pipeline systems. Whether in municipal water supply, oil and gas transportation, or industrial pipelines, this technology plays a crucial role. For laypeople, pipe opening and branch connection may seem like a simple mechanical operation, but in fact, it is a professional skill that integrates knowledge from multiple disciplines such as mechanical engineering, materials science, and fluid mechanics. 01 Technology Type and Characteristics: Diversified Pipeline Opening Techniques The pipe opening and branch pipe connection technology is divided into two main categories based on different construction conditions and requirements: pressure-bearing opening and non-pressure opening. Each technology has its own unique application scenarios and characteristics. Pressure-assisted hole-making is a type of hole-making operation carried out without interrupting the pipeline flow. This technology is applicable to pipeline systems that cannot be interrupted, such as main water supply pipes in cities and high-pressure oil and gas transportation pipelines. According to relevant research, the pressure-opening operation on high-pressure oil and gas pipelines falls under the category of extremely hazardous special-level hot work. It is highly dangerous and the entire construction process must ensure absolute safety. Non-pressure opening holes are the opening operations carried out when the pipeline is emptied and it is confirmed that there is no pressure. This method is relatively safe and simple to operate, but it will affect the normal operation of the pipeline system. Therefore, water or gas supply needs to be stopped for the operation. From the perspective of the opening method, it can be divided into vertical opening and oblique opening; from the connection form, there are various forms such as water-stop plug connection and three-way connection. When making holes in existing pipelines, strict adherence to technical specifications is necessary. For instance, no holes should be drilled on the bends and curved sections of the pipeline for installing water stop valves; if more than one hole is drilled on a single pipe, the minimum spacing between adjacent holes must be no less than seven times the diameter of the existing pipeline. These strict regulations are all designed to ensure the safe operation of the pipeline system. 02 Operation Process Analysis: Professional Steps for Making Pipe Holes and Connecting Branch Pipes Pipe opening and connection of branch pipes is a professional operation that must be carried out strictly in accordance with procedures. Its operation process is complex and meticulous. The preparatory work in the early stage is the foundation for successfully completing the pipe opening and connecting the branch pipes. Before the construction, on-site investigation is required to determine the opening position, inspect the condition of the pipes, and prepare the necessary tools and materials. Depending on the material of the pipeline, its diameter and the nature of the medium, appropriate opening tools and connection components need to be selected. For pressure-bearing opening operations, corresponding specifications and pressure grades of special equipment such as connection boxes, clamp valves and flange plugs must be fully prepared. Positioning and marking are the key steps to ensure the accuracy of the branch pipe positions. Before installing the main pipe, first draw or mark the horizontal lines on the wall according to the reserved pipe openings on the main pipe to determine the installation positions of the horizontal branch pipes. Then, on these horizontal lines, draw the center lines of each branch line or water supply fittings as per the design requirements. The accuracy of this step directly affects the quality of subsequent hole drilling and connection of branch pipes. The installation of the opening equipment is the core step in the process of pipe opening and connecting branch pipes. Taking pressure-bearing opening as an example, first, a special flange needs to be welded to the main pipe, then the clamp valve is connected to the flange, and finally the opening machine is installed. During the installation process, it is necessary to ensure the sealing of all connection parts to prevent medium leakage. For pipes of different materials, the selection of opening tools also varies. For example, for pipes of different materials such as steel pipes and ductile iron pipes, different cutting tools and rotational speeds need to be selected. The hole-making operation is a step that requires precise control. During the hole-making process, it is necessary to control the feed speed and cutting pressure properly to prevent damage to the tool or the pipeline. Using the new type of hole-cutting tool, with its angle designed specially and the tooth structure arranged in a specific way, the stability of hole cutting can be ensured. After the hole is cut, the tool needs to be returned to the sealing cavity, the valve needs to be closed, and the hole-cutting operation is completed. The connection of branch pipes is the final crucial step. At the beginning of the branch pipes with three or more water distribution points, as well as behind the water supply valves, according to the direction of water flow, detachable connectors (flanges) should be installed. After the branch pipes are installed, concrete must be poured for the thrust piers, foundation of the well chamber, and the construction of the well chamber and other ancillary structures as per the design requirements. 03 Technical Challenges and Solutions: The Challenges in Opening Holes in Pipes for Connecting Branch Pipes During the operation of opening holes in pipes to connect branch pipes, various technical difficulties may be encountered. These difficulties need to be resolved through professional techniques and rich experience. Space constraints are one of the common challenges. In the renovation project of the "Luanchuan Home Community" in Huai'an, the construction workers encountered a problem of small pipe shafts. They were so small that only one water meter could fit inside and it had to be installed vertically. There was basically no space for construction inside the pipe shaft. In response to this situation, the construction team innovatively proposed a solution: cutting each layer's main pipe into two smaller ones, drilling holes in the pipe shaft, and then lowering the cut-off pipes from top to bottom through the drilled holes, and directly re-connecting them with pipes of the same diameter. The drilling of holes in special material pipes is also a technical challenge. The pipes used in long-distance oil and gas pipelines are mostly high-strength pipeline steel, with high hardness. Especially for large-diameter natural gas pipelines, the X80 steel used poses significant difficulties for the hole-drilling operation. To address this issue, the professional technical team used high-strength hard alloy materials and selected a specially designed and multi-toothed structure for the hole-cutting tool, ensuring the stability of the hole-making process and eliminating the need for welding expansion rings. The sealing performance guarantee is the key difficulty in pressure-opening operations. If the sealing integrity cannot be ensured during the sealing process, it will bring uncontrollable risks and potential hazards to subsequent operations such as pipe cutting and joint connection that require hot work. The old-style sealing components mainly use a "locking pin" structure for the fixation and positioning of the "plug cake", which is prone to leakage. The new sealing device has abandoned the traditional lip sealing method and adopted a multi-line sealing method, which solves the problem of difficult sealing under high and low pressure conditions of the pipeline. The control of hole opening accuracy has a very high requirement for the technical proficiency of the operators.