API5L X60 straight seam steel pipe, with its high-precision inner and outer diameter control and advanced weld heat treatment process, has become a core material for oil and gas transportation. This pipe strictly adheres to API5L standards, with an outer diameter tolerance within ±0.75% (for example, for a 406.4mm outer diameter pipe, the tolerance is approximately ±3.05mm), a wall thickness deviation ≤±10%, and a straightness error of no more than 1.5mm per meter. During production, a laser diameter gauge monitors pipe dimensions in real time, coupled with a hydraulic closed-loop control system, ensuring inner and outer diameter accuracy meets the requirements of extreme operating conditions such as deepwater and polar regions. For example, a Central Asian pipeline project requires an ovality of ≤0.6%. High-precision forming is achieved using a five-roll finishing mill, laying the foundation for subsequent welding and corrosion protection processes.
Weld heat treatment is a key technology for API5L X60 straight seam steel pipe. After welding, the steel pipe undergoes either online medium-frequency induction heating or offline overall heat treatment to eliminate residual weld stress and optimize the microstructure. For X60 steel, for example, the weld area undergoes quenching and high-temperature tempering (quenching and tempering) to transform the microstructure into tempered bainite, achieving a balance of strength, hardness, and toughness. Specific process parameters include: quenching at 850-900°C, holding, and rapid cooling to room temperature; tempering at 580-620°C, holding for 2-3 hours, and air cooling. This process significantly improves the weld’s impact toughness, achieving longitudinal impact energy ≥40J and transverse impact energy ≥27J at 0°C, meeting PSL2 requirements.
The synergistic optimization of high-precision inner and outer diameters and weld heat treatment ensures that API5L X60 straight seam steel pipe possesses excellent mechanical properties and corrosion resistance. Its yield strength ≥415MPa, tensile strength ≥520MPa, and elongation ≥18% are sufficient to withstand high-pressure fluid transportation. At the same time, improved microstructural uniformity in the weld area reduces the risk of hydrogen-induced cracking (HIC) and sulfide stress corrosion (SSCC), extending pipeline service life. For example, a shale gas extraction project uses X60 bimetallic composite pipe lined with a corrosion-resistant alloy. Through optimized weld heat treatment, the annual corrosion rate has been reduced to <0.01mm/year, significantly improving pipeline reliability.
API5L X60 straight seam steel pipe, with its high-precision dimensional control and advanced weld heat treatment technology, is an ideal choice for long-distance oil and gas transportation and urban pipeline construction, providing reliable guarantees for energy security and efficient transmission.
Post time: Aug-11-2025