X90Q straight seam steel pipe is a high-end pipe material used in oil and gas transportation. Its manufacturing process and performance indicators are directly related to the safety and economy of energy transportation. According to the API 5L standard, this type of steel pipe must meet stringent mechanical properties, chemical composition, and processing requirements, particularly offering significant advantages in high strength, low-temperature toughness, and corrosion resistance. The following is a comprehensive technical analysis and industry application of this product:
First, Material Characteristics and Standard Specifications of X90Q Longitudinal Welded Pipe
X90Q belongs to the PSL2 grade pipeline steel in the API 5L standard. The letter “Q” indicates quenching and tempering heat treatment. Its minimum yield strength reaches 90 ksi (approximately 620 MPa). The technical parameters provided by suppliers in the search results indicate that this type of steel pipe typically utilizes a microalloying design, with strict control of the carbon equivalent (Ceq ≤ 0.43) and crack sensitivity coefficient (Pcm ≤ 0.25) in the chemical composition to ensure weldability. Typical mechanical properties include: – Tensile strength ≥ 690 MPa – Elongation ≥ 18% – Average Charpy impact energy at -20°C ≥ 100 J
Second, Key Production Process Points for X90Q Longitudinal Welded Pipe
1. Coil Preparation: Wide and thick plates are rolled using the TMCP (Thermo-Mechanically Controlled Process), with fine-grained bainite structure achieved through in-line accelerated cooling.
2. Forming and Welding Technology:
Mainstream production processes include JCOE forming and multi-wire submerged arc welding (SAWL), including:
- Pre-welding utilizes high-frequency induction welding (ERW) to ensure forming accuracy
- Internal and external welding utilizes four-wire tandem submerged arc welding, increasing deposition efficiency by 40%
- 100% real-time X-ray inspection of welds, with a defect detection sensitivity of up to 0.5 mm
3. Heat Treatment System: The quenching temperature is controlled at 900 ± 10°C, and the tempering process utilizes zoned temperature control technology to keep performance fluctuations within ±5% along the entire length of the pipe. A company’s technical documentation mentions that its heat treatment line is equipped with an infrared temperature measurement closed-loop system, achieving a temperature control accuracy of ±3°C.
Third, the quality inspection system for X90Q straight seam welded pipes.
1. Nondestructive Testing:
- Ultrasonic testing (UT) covers the weld and base material, capable of identifying flat-bottom hole defects as small as 0.8mm.
- Magnetic particle testing (MT) is used for surface crack screening, with sensitivity meeting ISO 17638 standards.
- Hydrostatic test pressure reaches 1.5 times the standard requirement, with a holding time of ≥10 seconds.
2. Physical and Chemical Property Verification:
- A set of specimens is taken from every 50 tons for full testing.
- Hydrogen-induced cracking (HIC) testing is conducted in NACE TM0284 standard solution, with a crack sensitivity rate (CSR) of ≤2%.
- SSC stress corrosion testing is verified using NACE TM0177 Method A solution.
Fourth, Typical Application Scenarios for X90Q straight seam welded pipes.
1. Pipeline projects in high-altitude cold regions: For example, natural gas pipeline projects. X90Q steel pipe maintains a DWTT shear area of ≥85% at -45°C. One supplier’s case study demonstrates successful application in the Yamal project within the Arctic Circle. 2. Deepwater Oil and Gas Development: Based on the technical specifications of the companies listed in the search results, this type of steel pipe is DNV GL-OS-F101 certified, can be laid in water depths up to 1,500 meters, and has an external pressure resistance of up to 25 MPa.
3. Sour Environment Transportation: When transporting media containing H₂S, the product must meet ISO 15156 standards and maintain a hardness of ≤22 HRC. Technical documentation indicates that the addition of alloying elements such as Cu and Ni can reduce the corrosion rate to below 0.1 mm/year.
Fifth, Market Supply Status of X90Q Longitudinal Welded Pipe
According to B2B platform data, there are currently approximately 15 manufacturers in China capable of mass-producing X90Q steel, 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
In terms of price, affected by price fluctuations of alloys such as molybdenum and niobium, the market price in July 2025 remained at 8,500-9,500 yuan/ton (FCA), representing a premium of approximately 30% over ordinary X70 steel pipe.
Sixth, Technical Development Trends of X90Q Longitudinal Welded Pipe
1. Intelligent Manufacturing and Forming: Some companies have introduced vision-guided automatic welding systems, achieving weld seam tracking accuracy of 0.2mm, such as the six-axis robot welding workstation demonstrated in a manufacturer’s video.
2. Green Production Process: Induction heating replaces gas furnaces, reducing energy consumption by 40%; the pickling process is replaced by mechanical shot blasting, achieving zero wastewater discharge.
3. Composite Pipe Development: Trial production of X90Q composite pipe lined with 625 alloy has begun, with an expected service life extension of up to 50 years.
With the accelerated construction of oil and gas pipeline networks during the 14th Five-Year Plan period, the use of X90Q straight seam welded pipe in applications such as high-voltage trunk lines and polar pipelines will continue to increase. Purchasers are advised to focus on the company’s API 5L certification, historical project performance, and third-party testing reports to ensure the reliability of the material throughout its lifecycle. In the future, this product will develop towards higher steel grades (X100/X120) and more intelligent technology, becoming a core material of choice for long-distance energy transmission.
Post time: Aug-26-2025