Applications of Large-Diameter Steel Pipes

1. Water Conservancy and Municipal Water Transmission
This is the most typical application for large-diameter steel pipes, frequently used in inter-regional water diversion projects and as primary municipal water supply mains.

Specific Applications: In large-scale water diversion projects—such as the Han River-to-Wei River Diversion Project—spiral-welded steel pipes with diameters reaching 3,448 mm or even 3,880 mm are employed for water transport.

Technical Characteristics: Such pipes must typically withstand high pressure and adapt to complex environments, including underground burial or utility tunnels. In recent years, grooved connection technology (for diameters ranging from DN350 to DN2000) has gained increasing traction in long-distance water transmission networks due to its rapid installation capabilities and ability to accommodate ground settlement.

2. Energy, Power, and Petrochemicals
In ultra-supercritical thermal power plants, nuclear power facilities, and large-scale petrochemical projects, large-diameter steel pipes are used to transport high-temperature, high-pressure steam or hazardous media.

"Four Major Piping Systems" in Power Plants: This refers to critical piping such as main steam lines and hot/cold reheat steam lines. For instance, P91 hot-expanded seamless steel pipes (Φ953 mm × 33 mm) are utilized in the hot reheat steam lines of 660 MW ultra-supercritical power units, operating at temperatures up to 569°C.

Localization of High-End Materials: Large-diameter, thick-walled G115 steel pipes have been deployed in 630°C ultra-supercritical demonstration projects, while P92 steel pipes serve as a key material for 600°C ultra-supercritical units, with an annual demand exceeding 100,000 tons.

Petrochemical Sector: In the 40-million-ton integrated refining and chemical project of Zhejiang Petrochemical, nearly 150,000 tons of steel piping were supplied, including over 25,000 tons of hot-expanded pipes.

3. Building Structures and Bridges
Leveraging their high flexural rigidity and load-bearing capacity, steel pipes are used as primary structural supports or foundations for large-scale buildings.

Bridges and Docks: These pipes are employed for bridge piling, subsea piling, and as arch rib structures for ultra-long-span arch bridges (typically with diameters exceeding 900 mm). Super-high-rise buildings: In the construction of settlement-related pour strips (post-pour strips), large-diameter seamless steel pipes are used as independent supports, circumventing the issues of long-term rental costs and susceptibility to corrosion associated with traditional scaffolding.

Offshore engineering: Large-diameter steel pipes are also extensively utilized in offshore wind power projects, such as for monopile foundations and cofferdams for artificial islands.

4. Offshore Oil & Gas and Specialized Equipment
Jack-up drilling rigs: The support pipes for the rig’s legs must withstand immense cyclic (alternating) loads. For instance, the JU2000E platform employs X80-grade seamless steel pipes with an outer diameter of Φ323.85 mm (approaching the large-diameter category). These pipes are required to have a yield strength of 610 MPa and exhibit excellent low-temperature toughness (with a ductile-to-brittle transition temperature below -80°C).