As a high-end steel pipe for oil and gas transportation, X90Q straight seam steel pipe’s manufacturing process and performance indicators are directly related to the safety and economic efficiency of energy transportation. According to the API 5L standard, this type of steel pipe must meet stringent mechanical property, 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 Straight Seam Steel Pipe
X90Q is a PSL2 grade pipeline steel in the API 5L standard. The “Q” designates quenching and tempering heat treatment, resulting in a minimum yield strength of 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) 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 Straight Seam Steel 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 states that its heat treatment line is equipped with a closed-loop infrared temperature measurement system with a temperature control accuracy of ±3°C.
Third, Quality Inspection System
1. Nondestructive Testing
- Ultrasonic testing (UT) covers welds and base metal, 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.
- The 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 for every 50 tons of steel 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
1. Pipeline projects in high-altitude cold regions: For example, natural gas pipeline projects require X90Q steel pipe to maintain a DWTT shear area of ≥85% at -45°C. A supplier’s case study shows that its products have been successfully used 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. Acidic 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, Technological Development Trends
1. Intelligent Manufacturing: Some companies have introduced vision-guided automated welding systems, achieving weld seam tracking accuracy of 0.2 mm.
2. Green Production Processes: Induction heating replaces gas furnaces, reducing energy consumption by 40%; the pickling process has been 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 longitudinally welded pipe in applications such as high-pressure trunk lines and polar pipelines will continue to increase. Purchasers are advised to focus on the company’s API 5L certification, historical engineering 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-21-2025