First, the material properties and standard requirements of L450M straight seam steel pipe.
L450M straight seam steel pipe belongs to micro-alloyed high-strength steel, with a minimum yield strength of 450MPa (65ksi). Its chemical composition adopts a low-carbon design (typically C≤0.12%), and adds micro-alloying elements such as Nb, V, and Ti. According to API 5L 46th edition standard, its key technical indicators include:
- Mechanical properties: Yield strength 450-570MPa, tensile strength 535-760MPa, Charpy impact energy at -20℃ ≥68J
- Dimensional tolerances: Outer diameter deviation ±0.75%, wall thickness deviation +15%/-12.5%
- Non-destructive testing: 100% ultrasonic or X-ray inspection is required to ensure weld quality.
Compared to spiral welded pipes, straight seam welded pipes have higher geometric dimensional accuracy and more uniform weld stress distribution, making them particularly suitable for high-pressure (typically above 10MPa) transportation conditions. L450M straight seam steel pipes, processed using the controlled rolling and cooling (TMCP) process, can also improve low-temperature toughness while maintaining strength, meeting the requirements of harsh environments such as the Arctic.
Second, the production process of L450M straight seam steel pipes.
Modern L450M straight seam steel pipes mainly adopt JCOE or UOE forming processes. The specific production process includes:
1. Steel plate pretreatment: Hot-rolled coils with a width of 1.5-2.5m are selected, and after leveling and milling, a welding bevel is formed.
2. Forming and welding
- JCOE process: The pipes are progressively pressed into a “J-C-O” shape, followed by pre-welding, internal welding (multi-wire submerged arc welding), and external welding.
- UOE process: A process of U-shaped pressing → O-shaped pressing → mechanical diameter expansion is used, resulting in higher forming efficiency.
3. Post-processing: This includes diameter expansion (to improve roundness), hydrostatic testing (usually 1.5 times the design pressure), and anti-corrosion treatment (3PE or FBE coating). The L450M straight seam steel pipes used in the PetroChina West-East Gas Pipeline III project employ double-layer fusion-bonded epoxy powder coating technology.
Third, Application Scenarios of L450M Straight Seam Steel Pipe.
- Oil and Gas Transportation: Natural gas pipelines (Φ1422mm) extensively utilize L450M straight seam steel pipes, designed for a pressure of 12MPa.
- Offshore Pipelines: In oilfield development projects, subsea pipelines use L450M straight seam steel pipes with a wall thickness of 22mm.
- Special Environments: Coal-to-gas export pipelines maintain good impact toughness even at -40℃.
It is worth noting that in the field of hydrogen energy pipelines, L450M straight seam steel pipes, after special heat treatment, can also be used for hydrogen transportation.
Fourth, Development Trends of L450M Straight Seam Steel Pipe
1. Intelligent Manufacturing: A demonstration factory introduced an AI weld inspection system, increasing the defect detection rate to 99.97%.
2. Green Production: Induction heat treatment replaces natural gas heating, reducing energy consumption by 40%.
Post time: Jan-06-2026