What are the key points for choosing pressure-sealing methods? Mastering these core points will help you avoid unnecessary detours. In pipeline maintenance, repair, renovation and expansion projects, the pressure-sealing technology is highly favored due to its ability to perform operations without interrupting the flow. However, in the face of various sealing techniques on the market, different brands of equipment, and unevenly skilled construction teams, how to make the right choice has become a problem that pipeline operation units and engineering managers must confront. Someone asks: What are the tricks for choosing the pressure-sealing technology? The answer is not simply "choose the expensive one" or "choose the familiar one". The real trick lies in: based on the actual working conditions of the pipeline, the operation goals, safety requirements and cost constraints, systematically evaluate and match the most suitable plugging solution, equipment and team. This article will combine industry practice and from multiple dimensions such as technology, management and safety, reveal the practical tips for choosing pressure-bearing plugging, and help you make wise decisions in complex and changing engineering conditions. I. Understanding Pressure-Resistant Sealing: First, clarify "What are you trying to seal and where are you going to seal it?" Before choosing a pressure-sealing solution, the following three core issues must be clarified: What is the medium inside the pipeline? The properties of the medium determine the safety level of the sealing and the selection of the sealing material. Natural gas, crude oil, refined oil, water, steam, and chemical media (such as acids, alkalis, ethylene, ammonia) have completely different requirements for the corrosion resistance, temperature resistance, and explosion prevention of the sealing device. 2. What are the operating parameters of the pipeline? · Pressure: Low pressure (< 1.6 MPa), medium pressure (1.6 - 4.0 MPa), high pressure (4.0 - 10 MPa), and even ultra-high pressure (> 10 MPa), corresponding to different structural strength requirements of the sealing devices and sealing pressure ratios. · Temperature: Ambient temperature, high temperature (such as in steam pipelines), and low temperature (such as in LNG pipelines) all directly affect the selection of sealing materials. · Pipe diameter and wall thickness: Small diameter (below DN50), conventional diameter (DN100 - DN500), large diameter (above DN600). Different diameters require matching with different specifications of sealing heads. · Pipe material and welding performance: The materials such as steel pipes, PE pipes, and ductile iron pipes determine whether to use welded or mechanical pipe fittings. 3. What are the objectives of the assignment? · Local repair: Replace a damaged section of the pipeline. This requires double sealing, double plugging, and the establishment of a bypass. · Add branches: Make holes in the main pipe and install branch pipes. Only one point of hole opening is required, and there is no need to seal it. · Valve replacement: Both upstream and downstream need to be blocked to isolate the working pipeline section. · Pipeline relocation: It may require multiple points of blocking, pipe cutting, and jointing, making the process quite complex. Tip 1: Conduct diagnosis first, then select the type. Do not skip the on-site investigation and data collection stages. Without accurate pipe parameters, any "empirical selection" is blind. II. Six Key Tips for Selecting Pressure-Resistant Sealing Technology Tip 1: Based on the pipeline pressure and the medium, determine the sealing technology route Pressure-sealing techniques can be mainly divided into the following several technical routes, each applicable in specific scenarios: Technical Route Applicable Pressure Applicable Medium Characteristics Tubular sealing: Low and medium pressure gas and liquid. The structure is simple and the cost is low, but the sealing surface is in line contact. Sealing plug, high pressure, natural gas, petroleum. The seal is reliable and can adapt to the ellipticity of the pipeline. However, the operation is complex. Folded sealing: High and medium pressure gas and water are introduced through smaller openings, saving pipe fitting dimensions and suitable for compact spaces. Freeze sealing - Low pressure - Water, oil - No need to drill holes, but only suitable for temporary and short-term sealing. Expansion cylinder sealing: Low and medium pressure water and sewage. Fast operation, but with limited pressure-bearing capacity. Key points: For high-pressure and high-risk media, plug-type sealing or imported high-end cylinder-type sealing should be chosen; for low-pressure water and oil media, domestic standard cylinder-type sealing can be used; when a very small opening is required, consider folding sealing; for temporary emergencies, consider using cryogenic sealing, but it cannot replace mechanical sealing for long-term isolation. For instance, in the emergency repair of long-distance natural gas pipelines (with a pressure of over 6.0 MPa), the industry consensus is to use plug-type sealing or highly reliable cylindrical sealing methods, and to combine them with a dual-sealing and dual-blocking plus bypass solution. However, in the local maintenance of urban water supply pipelines (with a pressure of 0.5 MPa), expansion cylinder sealing or even pressure-resistant emergency clamp may be more cost-effective. Tip 2: Select equipment and construction methods based on the working space and environment. Pressure-sealing equipment is usually heavy and large in size. The accessibility conditions at the operation site, the size of the working pit, whether it involves water, and whether it is at a height all directly determine whether the equipment can be brought in and how it should be installed. · Open flat space: Standard type or split-type equipment can be selected. Cranes and hydraulic stations can all operate normally. · Mountain slopes: Modular and lightweight equipment should be selected, or remote control operation can be adopted. Equipment fixation requires anchors and anti-slip measures. Professional manufacturers such as Cangzhou Aoguang Machinery Equipment Co., Ltd. have developed compact sealing machines specifically for mountainous conditions, which can complete the operation within limited spaces. · Narrow urban streets: Preferentially select miniaturized and low-profile equipment, or adopt non-digging internal sealing technology.