Application of large-diameter seamless steel pipes and their technological development
Date:2025-04-28View:22Tags:OCTG pipe,Seamless steel pipe manufacturer,Casing and tubing
Large-diameter seamless steel pipes (usually seamless steel pipes with an outer diameter of more than Φ406mm) play an irreplaceable role in energy, chemical, electric power, marine engineering and other fields due to their high strength, high pressure resistance, corrosion resistance and good sealing properties. With the continuous improvement of modern industry's requirements for material performance, the manufacturing technology of large-diameter seamless steel pipes has continued to break through, and the application scenarios have continued to expand, becoming one of the key materials supporting major national projects and high-end equipment manufacturing.
I. Core materials in the field of energy transportation
1. Long-distance oil and natural gas pipelines
In the long-distance transportation of oil and gas resources, large-diameter seamless steel pipes are the "blood vessels" for building trunk pipelines. For example, the China-Russia East Line Natural Gas Pipeline uses X80 grade steel and seamless steel pipes with a diameter of 1422mm. The single-pipe gas transmission capacity is increased by 30%, and the risk of leakage is significantly reduced by reducing the number of welds. In deep-sea oil and gas development, L360QS grade seamless steel pipes that are resistant to hydrogen sulfide corrosion are used for submarine pipelines, which can withstand high pressure and complex marine environments.
2. Liquefied Natural Gas (LNG) and Hydrogen Energy Storage and Transportation
With the development of new energy, LNG receiving stations and hydrogen energy pipelines have higher requirements for materials. Large-diameter steel pipes need to maintain toughness at ultra-low temperatures of -196°C (such as 9% Ni steel) and adapt to the hydrogen embrittlement resistance in hydrogen environments. A domestic LNG project uses duplex stainless steel seamless pipes and successfully achieves low-temperature transportation at minus 162°C.
2. Key support for high-end equipment manufacturing
1. "Safety barrier" in nuclear power equipment
Large-diameter thick-walled seamless steel pipes are required for the main steam pipelines of nuclear power plants, reactor pressure vessel pipes, and other parts. The materials must have both high-temperature strength (such as SA-335 P92 steel with a strength of more than 100MPa at 620°C) and resistance to neutron irradiation embrittlement. The Hualong One unit uses domestically produced nuclear-grade seamless steel pipes with a wall thickness of 80mm, which ensures the safe operation of the nuclear island.
2. High temperature resistant parts of supercritical thermal power units
In 630℃ ultra-supercritical units, HR3C (25Cr-20Ni-Nb-N) austenitic heat-resistant steel seamless pipes are used for superheaters. Their endurance strength is more than twice that of traditional materials, significantly improving power generation efficiency. A 1000MW unit project uses large-diameter steel pipes to reduce the number of pipe rows by 20% and reduce the risk of thermal deviation.
III. Marine engineering and special environment applications
1. Deep-sea oil and gas production equipment
Underwater Christmas trees, jumper pipes and other equipment require the use of titanium alloy or duplex steel large-diameter pipes. For example, a gas field in the South China Sea uses Φ508mm 2205 duplex stainless steel pipes, which have a Cl⁻ corrosion resistance of 5 times that of ordinary steel and meet the external pressure stability requirements at a water depth of 1500 meters.
2. Polar engineering and special geological conditions
The Yamal LNG project in the Arctic uses X70 steel grade seamless pipes with low temperature toughness of -60℃. The grains are refined through controlled rolling and controlled cooling process to ensure that the pipes do not suffer brittle fracture during construction in the permafrost zone. In addition, large deformation resistant steel pipes (such as X80 HD2) are used for pipelines in seismically active areas, which can absorb more than 2% axial strain.
IV. Technical challenges and development trends
1. Manufacturing process breakthroughs
Hot extrusion technology: 10,000-ton extruders can produce extra-large diameter pipes above Φ1200mm, reducing the eccentricity of traditional perforation methods.
Online heat treatment: The strength and toughness matching of X100 high-grade steel pipes is improved through DQ (direct quenching) + T (tempering) process.
Intelligent detection: Electromagnetic ultrasonic (EMAT) is used to achieve wall thickness accuracy control of ±0.5mm, and magnetic leakage detection can identify 0.3mm deep cracks.
2. Material innovation direction
Lightweight design: Aluminum-magnesium alloy composite pipes and carbon fiber reinforced pipes have gradually entered the test stage, reducing weight by more than 40% compared with traditional steel pipes.
Functional coating: Graphene-modified epoxy coating can extend the anti-corrosion life to 50 years and is suitable for submarine pipelines.
Special materials for hydrogen energy: Develop hydrogen embrittlement-resistant steel pipes with surface nano-treatment, and reduce the hydrogen diffusion coefficient by 2 orders of magnitude.
