X65M longitudinally welded steel pipe is a high-strength pipeline steel widely used in long-distance oil and natural gas pipeline projects. It offers excellent mechanical properties, weldability, and corrosion resistance. With the growing global demand for energy, X65M longitudinally welded steel pipe enjoys broad application prospects in both domestic and international markets, becoming a key material in pipeline construction.
First, Basic Characteristics of X65M Longitudinal Welded Steel Pipe
X65M longitudinally welded steel pipe is a high-strength pipeline steel produced in accordance with API 5L standards. Its minimum yield strength is 450 MPa (65 ksi). It is produced using the micro-alloyed controlled rolling and controlled cooling (TMCP) process. Its chemical composition maintains a low carbon content (typically ≤0.12%) and extremely low levels of harmful elements such as sulfur and phosphorus (≤0.005% and ≤0.020%, respectively), significantly enhancing the pipe's resistance to hydrogen-induced cracking (HIC) and sulfide stress corrosion cracking (SSCC).
Second, the production process and key technical points of X65M straight seam welded steel pipe. Modern X65M straight seam welded steel pipe is primarily produced using the JCOE or UOE forming processes. For example, a large steel pipe manufacturer's production line is equipped with pre-welding machines from SMS Meer in Germany and multi-wire submerged arc welding equipment from Lincoln Electric in the United States. This allows the production of a series of products with diameters ranging from 406 to 1422 mm and wall thicknesses ranging from 6 to 40 mm. Key production processes include:
- Plate edge processing: A milling machine is used to precisely machine the steel plate edges, ensuring a bevel angle of 30° ± 2° and a blunt edge height of 1.5 ± 0.5 mm, creating ideal conditions for subsequent welding.
- Pre-bending: A seven-roll pre-bending machine pre-bends the steel plate edges to eliminate the "straight edge effect" during subsequent JCO forming. Actual measurement data from one factory shows that an optimized pre-bend radius can reduce residual stress by over 40%.
- Multi-step stamping: A computer-controlled hydraulic press is used for progressive JCO forming, typically requiring 7-9 passes to complete the entire forming process. The newly introduced 6,000-ton hydraulic press achieves a positioning accuracy of ±0.1mm, increasing forming efficiency by 30%.
- Diameter Expansion: Using mechanical or hydraulic expansion technology, actual measurements on one project show that after a 12% expansion rate, the roundness error of the steel pipe can be controlled within 0.6%D, significantly improving pipe assembly accuracy.
Third, Quality Control and Inspection Technology for X65M Straight-Seam Welded Steel Pipe
1. Raw Material Inspection: Composition analysis is performed using a Direct Emission Spectrometer (OES), and inclusion classification is performed using a Zeiss metallographic microscope. Inspection reports for one batch show that the actual sulfur content is controlled between 0.0012% and 0.0028%, well below the standard requirement.
2. Online Monitoring System: An ultrasonic thickness gauge from Thermo Fisher Scientific Inc. is installed to monitor wall thickness deviation in real time, with a system sensitivity of 0.05mm. Statistics show that the wall thickness qualification rate has increased to 99.97% after implementing this system. 3. Nondestructive Testing: Combining ultrasonic testing (UT) and eddy current testing (ET), the newly introduced phased array ultrasonic testing system (PAUT) can detect flaws as small as 0.3mm in equivalent diameter at a speed of 2.5m/min.
Fourth, Typical Engineering Applications of X65M Longitudinal Welded Steel Pipe
In natural gas pipeline projects, X65M longitudinally welded steel pipe has set multiple application records. The project employed 1422mm diameter, 21.4mm wall thickness steel pipes, each weighing 7.8 tons and designed for a pressure of 12MPa. Of particular note:
Low-temperature adaptability: At -40°C, the pipe maintains a Charpy impact energy of 186-243J, fully meeting the requirements for use in Russia's extremely cold regions. A third-party testing report shows that the shear area ratio of the DWTT at -45°C reaches 98%.
Fifth, Market Status and Development Trends of X65M Longitudinal Welded Steel Pipe
1. Larger Sizes: Demand for large-diameter steel pipes larger than 1422mm has seen an annual growth rate of 12%. A Middle Eastern project has begun evaluating the feasibility of 1620mm diameter pipes.
2. Higher Strength: The share of X70M and above steel grades has increased to 28%, but X65M remains dominant (with approximately 65% market share) due to its excellent price-performance ratio.
3. Intelligent Manufacturing: Leading companies have deployed 5G+ industrial internet platforms. One demonstration factory has reduced defective product rates by 40% and energy consumption by 15% using digital twin technology.
Sixth, Usage and Maintenance Recommendations for X65M Longitudinal Welded Steel Pipe
1. Storage Management: Steel pipes should not be stacked more than five layers high, and the spacing between supports should be no greater than one-third of the pipe length. Experience from a specific project has shown that the use of rubber pads can reduce pipe end deformation by 60%. 2. Welding Preheating: When the ambient temperature is below 5°C, preheating to 80-120°C is required. Practical data shows that proper preheating can reduce the incidence of cold cracking from 3.2% to 0.5%.
3. Cathodic Protection: The recommended protection potential is maintained between -0.85 and 1.15V (CSE). A submarine pipeline monitoring system demonstrated that an optimized protection scheme reduced the corrosion rate to 0.02mm/year.
4. Regular Inspection: Internal Lift Inspection (ILI) is recommended every five years. The newly introduced electromagnetic ultrasonic testing technology (EMAT) can simultaneously assess pipe defects and coating condition, achieving an accuracy of ±0.3mm.
In summary, X65M straight seam welded steel pipe, as a core material in modern pipeline engineering, continues to advance in both technical level and application scale. With continuous breakthroughs in new materials and processes, this type of steel pipe will demonstrate outstanding performance in more demanding environmental conditions and complex service conditions, providing a solid foundation for global energy infrastructure construction.
Threeway Steel is known as a professional supplier engaged in manufacturing and distributing a wide range of steel pipe, and our headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
