GB/T 9711 PSL1 L290 LSAW
Product introduction
L290 welded pipe is characterized by its large diameter, thick wall, and strong pressure resistance, making it one of the preferred pipe types for long-distance oil and gas transmission trunk lines. Its moderate strength meets the pressure requirements of most conventional oil and gas transmission projects. It has good weldability, and the circumferential welding process during on-site laying is relatively simple, making it easy to ensure weld quality. Compared to PSL2 or higher grade steel pipes, its production cost and price are more competitive.
Parameter Table
PSL1 has relatively lenient requirements for chemical composition, typically specifying only the maximum carbon equivalent (Ceq) and maximum carbon content to ensure weldability. A typical chemical composition range for L290 PSL1 is as follows.
| Carbon (C | ≤ 0.22% |
| Manganese (Mn) | ≤ 1.20% |
| Phosphorus (P) | ≤ 0.025% |
| Sulfur (S) | ≤ 0.015% |
| Carbon Equivalent (Ceq) | Typically required to be ≤ 0.36% - 0.40% to ensure good weldability. |
Heat Treatment Processing
GB/T 9711 PSL1 L290 LSAW steel pipes, after welding and forming, typically undergo overall normalizing as their final heat treatment. This process uniformly heats the steel pipe to a suitable temperature above the Ac₃ phase transformation point (usually 880℃~930℃), causing the microstructure of the base metal, weld, and heat-affected zone to completely transform into fine austenite, followed by uniform cooling in still air. This process aims to eliminate post-weld residual stress, refine the grain size, and promote the transformation of inhomogeneous banded microstructure into uniform ferrite and pearlite, thereby significantly improving the plasticity and low-temperature toughness of the steel, ensuring the uniformity and stability of its mechanical properties to meet the standard's basic requirements for strength and toughness.
About our Company
GNEE - STEEL is a professional steel export supplier. Established in 2008, our company is an agent for multiple steel mills. Our main products include steel pipes, plates, bars, profiles, fittings, and valves. We cooperate with many top-tier domestic steel mills, ensuring reliable steel quality and rapid delivery, thus guaranteeing smooth project implementation.
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