In the current wave of marine resource development, submarine pipelines, as the key channels connecting the ocean and the land, are playing an increasingly important role. Their wide - ranging applications cover multiple fields, injecting strong impetus into the development of the marine economy.
Oil and Gas Transportation: The Submarine Extension of Energy Arteries
Submarine pipelines play a core role in the oil and gas transportation field. With the continuous growth of global energy demand, the development of offshore oil and gas resources has become more in - depth. A large amount of oil and natural gas is continuously transported from deep - sea production platforms to on - shore receiving stations through submarine pipelines. For example, in the second - phase project of China's "Deep - Sea No.1", the submarine long - distance pipeline uses 20 - inch submarine pipes, with a total length of 115.5 kilometers. It includes 114 kilometers of deep - water large - diameter seamless steel pipes and 1.5 kilometers of deep - water bimetallic composite pipes, which is the first application in China's deep - water environment. This pipeline is like an energy artery, efficiently and stably transporting deep - sea oil and gas resources to the land and ensuring the country's energy supply.
Longitudinal - welded pipes have unique advantages in submarine oil and gas transportation pipelines. Longitudinal submerged arc welded pipes (LSAW) are made from single medium - thick steel plates, which are pressed (rolled) into pipe blanks, double - sided submerged arc welded, and then expanded. They have a wide range of finished product specifications. The welds have good toughness, plasticity, uniformity, and compactness, and they feature large diameters, thick walls, high - pressure resistance, low - temperature resistance, and strong corrosion resistance. In large - scale oil and gas transportation pipelines, when passing through Class 1 and Class 2 areas such as alpine regions, the seabed, and densely populated urban areas, longitudinal submerged arc welded pipes are the only specified applicable pipe types. National pipeline projects such as the West - to - East Gas Pipeline project have used a large number of such longitudinal - welded pipes to ensure the safety and stability of energy transportation.
Comprehensive Marine Resource Development: Support for Multiple Fields
In addition to oil and gas transportation, submarine pipelines also play an important role in the comprehensive development of marine resources. In seawater desalination projects, submarine pipelines are used to transport seawater from the ocean to on - shore desalination plants. After treatment, they provide valuable fresh water resources for coastal areas. In the exploitation of marine mineral resources, submarine pipelines can be used to transport the mined ore pulp, transporting deep - sea mineral resources to the land for refining and processing.
Longitudinal - welded pipes perform excellently in these complex marine resource development scenarios due to their good dimensional accuracy and convenience for repair welding. Welding and butt - jointing pipes in the ocean are very difficult, and the requirements for the ovality, alignment, groove protection, and cross - sectional error of steel pipes are extremely high. Otherwise, the operation efficiency will be seriously affected. Longitudinal - welded pipes can well meet these requirements, ensuring the stable operation of the pipeline system in the long - term complex marine environment.
Technological Innovation Drives Development: Adapting to the Complex Marine Environment
As marine development advances to deeper and more distant waters, submarine pipelines are facing increasingly complex marine environmental challenges, such as high pressure, low temperature, strong corrosion, and complex seabed geological conditions. To address these challenges, relevant technologies are constantly being innovated. For example, in a submarine pipeline project in the South China Sea, an X65 - grade longitudinal - welded pipe with a double - layer FBE + PP anti - corrosion coating is used. By adding 0.06% Nb micro - alloying elements, the low - temperature impact energy at - 40°C reaches over 220J, greatly improving the performance of the pipeline in low - temperature and highly corrosive environments.
The manufacturing process of longitudinal - welded pipes is also continuously improving. The double - sided submerged arc welding process forms a fine acicular ferrite structure in the weld area, and its impact toughness is more than 30% higher than that of conventional welds. Longitudinal - welded pipes are more suitable for the automated expansion process. Through mechanical expansion, the roundness deviation can be controlled within 0.5% D, which is crucial for ensuring the pipe butt - joint accuracy and improving the overall project quality.
Submarine pipelines have become an indispensable infrastructure for the development of the marine economy due to their wide - ranging applications in oil and gas transportation and comprehensive marine resource development. Longitudinal - welded pipes, with their excellent performance and continuously innovative processes, occupy an important position in submarine pipeline construction, providing a solid guarantee for the efficient development and utilization of marine resources. In the future, they will surely play an even greater role in the field of marine engineering with the advancement of technology.
