As a high-end pipe material in the oil and gas transportation field, the manufacturing process and performance indicators of X90Q straight seam welded steel pipe directly affect the safety and economy of energy transportation. According to API 5L standards, this type of steel pipe must meet stringent requirements for mechanical properties, chemical composition, and processing, especially exhibiting significant advantages in high strength, low-temperature toughness, and corrosion resistance.
First, the material characteristics and standard specifications of API 5L X90Q straight seam welded steel pipe.
X90Q belongs to the PSL2 grade pipeline steel in the API 5L standard. The letter “Q” indicates that it has undergone quenching and tempering heat treatment, and its minimum yield strength reaches 90 ksi (approximately 620 MPa). Technical parameters provided by suppliers in search results show that this type of steel pipe typically employs a micro-alloying design, with strict control over carbon equivalent (Ceq≤0.43) and crack sensitivity coefficient (Pcm≤0.25) in its chemical composition to ensure weldability. Typical mechanical properties are: – Tensile strength ≥ 690 MPa – Elongation ≥ 18% – Average Charpy impact energy at -20℃ ≥ 100 J
Second, Key points of the production process for API 5LX90Q straight seam welded steel pipe.
1. Plate and coil preparation: Wide and thick plates rolled using TMCP (Thermomechanical Control Process) are used, and a fine-grained bainitic microstructure is obtained through online accelerated cooling.
2. Forming and welding technology: The mainstream production process includes JCOE forming + multi-wire submerged arc welding (SAWL), where:
- Pre-welding uses high-frequency induction welding (ERW) to ensure forming accuracy.
- Both inner and outer welding use four-wire tandem submerged arc welding, increasing deposition efficiency by 40%.
- Welds are inspected by 100% X-ray in real time, with defect detection sensitivity reaching 0.5 mm.
3. Heat treatment system: Quenching temperature is controlled at 900±10℃, and the tempering process uses zoned temperature control technology to keep the performance fluctuation of the steel pipe within ±5% along its entire length. A company’s technical document mentions that its heat treatment line is equipped with an infrared temperature measurement closed-loop system, achieving a temperature control accuracy of ±3℃.
Third, the quality inspection system for API 5LX90Q straight seam welded steel pipes.
1. Non-destructive testing
- Ultrasonic testing (UT) covers the weld and base material, capable of identifying flat-bottom hole defects equivalent to 0.8mm.
- Magnetic particle testing (MT) is used for surface crack screening, with sensitivity meeting ISO 17638 standards.
- Hydrostatic testing pressure reaches 1.5 times the standard requirement, with a holding time of≥10 seconds.
2. Physicochemical property verification
- One set of samples is taken for every 50 tons for comprehensive testing.
- Hydrogen-induced cracking (HIC) testing is conducted in NACE TM0284 standard solution, with a crack sensitivity rate (CSR) ≤2%.
- SSC stress corrosion testing is verified using the NACE TM0177 method.
Fourth, typical application scenarios for API 5LX90Q straight seam welded steel pipes.
1. High-altitude and cold region pipeline projects: Natural gas pipeline projects, where X90Q steel pipes maintain a DWTT shear area ≥85% even at -45℃.
2. Deep-sea oil and gas development: Based on the technical specifications of the companies in the search results, this type of steel pipe is DNVGL-OS-F101 certified, meeting the requirements for laying in water depths of 1500 meters and with an external pressure resistance of up to 25 MPa.
3. Transportation in acidic environments: When transporting media containing H₂S, the product must meet the ISO 15156 standard, controlling the hardness to ≤22 HRC. A technical document shows that by adding alloying elements such as Cu and Ni, the corrosion rate can be reduced to below 0.1 mm/a.
Fifth, Current Market Supply Status of API 5LX90Q Straight Seam Welded Steel Pipes.
Currently, there are approximately 15 manufacturers in China with mass production capacity for X90Q steel pipes, with an annual production capacity exceeding 2 million tons. Mainstream specifications are:
- Diameter: 406-1422mm
- Wall thickness: 6.4-40mm
- Single length: 10.5-12.5m
Regarding price, affected by fluctuations in the prices of alloys such as molybdenum and niobium, the market price in July 2025 remained at 8500-9500 yuan/ton (FCA), a premium of approximately 30% compared to ordinary X70 steel pipes.
Sixth, Technological Development Trends of API5LX90Q Straight Seam Welded Steel Pipes.
1. Intelligent Manufacturing: Some enterprises have introduced vision-guided automatic welding systems, achieving weld seam tracking accuracy of 0.2mm.
2. Green Production Process: Induction heating replaces gas furnaces, reducing energy consumption by 40%; pickling is replaced by mechanical shot blasting, achieving zero wastewater discharge.
3. Composite Pipe Development: Trial production of X90Q composite steel pipes lined with 625 alloy has begun, which is expected to extend service life to 50 years.
With the accelerated construction of oil and gas pipeline networks during the 14th Five-Year Plan period, the application rate of X90Q straight seam welded steel pipes in high-pressure trunk lines, polar pipelines, and other scenarios will continue to increase. Purchasers are advised to focus on the company’s API 5L certification level, historical project performance, and third-party testing reports to ensure the reliability of the material throughout its entire lifecycle. In the future, this product will develop towards higher steel grades (X100/X120) and more intelligent technologies, becoming a core material choice for long-distance energy transmission.
Post time: Nov-12-2025