I. Current Situation and Challenges in the High-Pressure Gas Field
With the continuous growth of energy demand, high-pressure gas transmission is crucial for the efficient distribution of energy. Currently, the global high-pressure gas supply system market is showing a steady growth trend. According to research by QYResearch, the global sales of high-pressure gas supply systems reached a certain scale in 2023, and it is expected to further increase by 2030, with a compound annual growth rate (CAGR) remaining at a certain level.
High-pressure gas transmission faces numerous challenges. From a technical perspective, high-pressure environments demand extremely high strength, tightness, and fatigue resistance of pipeline materials. For example, in deep-sea high-pressure gas fields, such as the second phase of China’s “Deep Sea No.1” project, the maximum formation pressure exceeds 69 megapascals, which is 1,000 times that of a household pressure cooker. This poses a huge challenge to the transmission pipelines. In terms of engineering construction, high-pressure gas pipelines often need to cross complex terrains, such as mountains, rivers, and seas. For instance, the Gangou – Xiquanlu high-pressure gas pipeline project in Jinan, with a total length of 17.8 kilometers, is entirely located in mountainous areas, passing through urban districts, central urban areas, and southern mountainous regions. During the construction process, it successively overcame many “crossing” difficulties, including the Ring Expressway, Jinan – Tai’an Expressway, as well as mountainous areas, dense forests, and river channels. It crossed 5 expressways and climbed over 6 mountains, with a vertical climb of nearly 200 meters, making the construction extremely difficult.
II. Traditional Limitations for PE Gas Pipes Entering the High-Pressure Field
For a long time, PE gas pipes have mainly been used in low and medium-pressure gas transmission scenarios (usually with a pressure ≤ 0.4MPa). This is due to some disadvantages of PE materials in high-pressure environments under traditional understanding and technical limitations. Firstly, the strength of PE materials is relatively lower than that of metal pipes. When withstanding high pressure, the wall thickness of the pipes needs to be significantly increased to ensure safety, which not only increases material costs but may also affect the convenience of construction. Secondly, the sealing problem under high pressure is also a major challenge. Although the hot-melt or electro-fusion connection methods of PE gas pipes can achieve good sealing under low and medium pressures, the joints face greater pressure tests in high-pressure environments. Once the sealing fails, the consequences will be disastrous. In addition, the environmental stress crack resistance of PE materials may experience slow crack growth under the long-term action of high pressure and high stress, affecting the long-term service life of the pipelines.
III. Recent Breakthrough Cases
(I) Breakthroughs in Material Innovation
- Research and Development of High-Strength PE Materials
Researchers have developed high-strength PE materials by improving the polymerization process and adding special additives. For example, some newly developed PE materials by enterprises have significantly improved tensile strength and impact resistance compared with traditional PE materials, which can meet the strength requirements of high-pressure gas transmission to a certain extent. These new materials enhance their compressive capacity while maintaining the original advantages of PE materials, such as corrosion resistance and good flexibility, providing a material basis for PE gas pipes to enter the high-pressure field. - High-Pressure-Resistant Composite PE Materials
Another innovative approach is to combine PE materials with other high-strength materials. For example, composite pipes with a structure of “PE outer layer + metal inner layer” have been developed. The inner metal layer provides high-strength pressure-bearing capacity, while the outer PE layer exerts its corrosion resistance and insulation properties. This composite structure not only solves the problem of insufficient strength when PE materials are used alone but also avoids the corrosion defect of metal pipes, greatly improving the applicability of the pipes in high-pressure gas transmission.
(II) Achievements in Process Improvement
- Optimization of Connection Processes
To address the sealing problem of joints in high-pressure environments, the connection processes of PE gas pipes have been deeply optimized. In terms of hot-melt connection, by precisely controlling the welding temperature, pressure, and time parameters and using advanced automated welding equipment, the welding accuracy and consistency are improved, resulting in higher joint strength and better sealing performance. For example, the new hot-melt welding process can ensure the full fusion of molecules at the joint, and in high-pressure tests, the sealing performance and strength of the joint can meet the standards of high-pressure gas transmission.
In the electro-fusion connection process, an intelligent electro-fusion welding system has been developed. This system can automatically adjust the welding parameters according to the pipe specifications and environmental conditions and monitor the welding process in real-time to ensure the welding quality. For example, in some high-pressure gas pilot projects, the PE gas pipes connected by intelligent electro-fusion have not shown any leakage or strength degradation during long-term high-pressure operation. - Enhancement of Manufacturing Processes
During the pipe manufacturing process, advanced extrusion processes and online monitoring technologies are adopted to ensure the uniformity of pipe wall thickness and quality stability. By optimizing the screw structure and temperature control system of the extrusion equipment, PE gas pipes with smaller wall thickness tolerances can be produced, improving the pressure-bearing capacity of the pipes under high pressure. The online monitoring technology can detect quality defects of the pipes in real-time, such as bubbles and impurities, and make timely adjustments and improvements to ensure that each pipe meets the strict standards of high-pressure gas transmission.
(III) Practical Application Projects
- Urban High-Pressure Loop Projects
In the construction of gas infrastructure in some cities, attempts have been made to use improved PE gas pipes to build high-pressure loops. For example, in the Gangou – Xiquanlu high-pressure gas pipeline project in Jinan, although the main difficulty of the project lies in crossing complex terrains, it also practically tests the performance of PE gas pipes in high-pressure environments. After the completion of this project, it seamlessly connects the South Loop (Guide – Xiquanlu) and the East Loop (Yaoqiang – Tangwang – Caofan) of Jinan, marking the initial formation of a complete loop for the city’s “gas network”. During the operation process, the PE gas pipes with special designs and process improvements have successfully withstood the high-pressure gas transmission pressure, providing a stable and reliable gas source guarantee for the city. - Specific Industrial High-Pressure Gas Supply Projects
In some industrial fields with high requirements for gas pressure, such as large chemical enterprises and steel plants, PE gas pipes are also beginning to be used for high-pressure gas supply. These enterprises have extremely high requirements for the stability and safety of gas. The PE gas pipes with improved materials and processes, with their excellent corrosion resistance, can effectively avoid safety hazards caused by the corrosion of pipes due to impurities in the gas. At the same time, their flexibility also facilitates laying and installation in complex factory areas, reducing construction costs and cycles.
IV. Impacts of the Breakthroughs
(I) Changes in the Industry Landscape
The breakthroughs of PE gas pipes in the high-pressure field have had a profound impact on the gas transmission industry landscape. On the one hand, the market share of metal pipes, which have traditionally dominated the high-pressure gas transmission field, is challenged. With the advantages of corrosion resistance, convenient construction, and relatively low costs, PE gas pipes are gradually gaining a share in high-pressure gas transmission projects. On the other hand, it prompts pipe manufacturing enterprises to increase their investment in the research and development of high-pressure technologies for PE gas pipes, accelerating the pace of technological innovation in the industry. At the same time, it also provides opportunities for some emerging pipe manufacturing enterprises. With advanced technologies and innovative products, they can stand out in the high-pressure gas pipe market.
(II) Cost and Benefit Analysis
- Cost Reduction
From the perspective of material costs, although the unit price of new high-strength PE materials or composite PE materials may be slightly higher than that of traditional PE materials, the overall cost is still advantageous compared with metal pipes. In terms of construction costs, the good flexibility of PE gas pipes allows for bending. When constructing in complex terrains, it reduces a large amount of earthwork and the use of pipe elbows and connectors, reducing construction difficulty and costs. For example, when laying high-pressure gas pipelines in mountainous areas, PE gas pipes can better adapt to terrain undulations, reducing pipeline laying difficulties and additional costs caused by terrain factors. - Benefit Enhancement
In terms of long-term operation benefits, the corrosion resistance of PE gas pipes eliminates the need for frequent anti-corrosion maintenance like metal pipes, reducing operation and maintenance costs. At the same time, their good sealing performance reduces the risk of gas leakage, which not only improves energy transmission efficiency but also avoids energy waste and safety hazards caused by leakage, bringing significant economic and social benefits.
(III) Improvement of Safety Performance
The PE gas pipes with improved materials and processes have significantly enhanced their safety performance in high-pressure environments. The high strength and environmental stress crack resistance of the new materials reduce the risk of pipeline rupture under long-term high-pressure action. The optimized connection process ensures the tightness and strength of the joints, effectively preventing gas leakage. For example, in some pilot projects, through regular pressure tests and non-destructive inspections of PE gas pipes, no safety hazards have been found, ensuring the safe and reliable operation of high-pressure gas transmission.
V. Future Development Trends
(I) Continuous R & D Directions
- Exploration of Higher-Performance Materials
In the future, researchers will continue to explore and develop PE materials with more excellent performance, such as further improving the strength, temperature resistance, and anti-aging properties of the materials. The goal is to develop PE gas pipes that can operate stably for a long time under higher pressures (such as over 10MPa) and higher temperatures (such as above 60°C) to meet the broader needs of high-pressure gas transmission, including some special industrial scenarios and gas transmission in extreme environments. - R & D of Intelligent Pipes
Combining the Internet of Things and sensor technologies, PE gas pipes with built-in intelligent sensors will be developed. These sensors can monitor the pressure, temperature, flow rate inside the pipeline, as well as the health status of the pipes in real-time, such as the presence of cracks and deformations. By transmitting this data to the monitoring center in real-time, intelligent management and early warning of high-pressure gas pipelines can be achieved, enabling the early detection and resolution of potential safety issues.
(II) Expansion of Application Scenarios
- Marine High-Pressure Gas Transmission
With the continuous development of offshore oil and gas resources, the demand for marine high-pressure gas transmission is increasing. PE gas pipes, with their advantages of corrosion resistance and light weight, have broad application prospects in the field of marine high-pressure gas transmission. In the future, it is expected to see more marine high-pressure gas transmission projects using PE gas pipes, connecting offshore oil and gas fields with onshore receiving stations or carrying out high-pressure gas transmission between offshore platforms. - Long-Distance High-Pressure Gas Transmission
In the aspect of long-distance high-pressure gas transmission on land, PE gas pipes may also become an important choice. Through continuous improvement of materials and processes, their reliability and economy in long-distance transmission can be enhanced, reducing the number of intermediate booster stations and lowering construction and operation costs, thus achieving more efficient and safer long-distance high-pressure gas transmission.
VI. Conclusion
PE gas pipes are gradually making breakthroughs in the high-pressure gas field. From material innovation to process improvement, and then to the successful implementation of practical application projects, all demonstrate their potential in high-pressure gas transmission. These breakthroughs not only change the industry landscape but also bring many benefits such as cost reduction and safety performance improvement, and also point out the direction for future development. With continuous R & D investment and technological innovation, PE gas pipes are expected to occupy a more important position in the high-pressure gas field, providing higher-quality, more efficient, and safer solutions for global energy transmission.
