In the oil and gas transportation sector, X100M straight seam welded steel pipe, as a representative of high-strength pipeline steel in the API 5L standard, is reshaping industry technical standards with its superior mechanical properties and engineering adaptability. Manufactured using high-frequency electric resistance welding (ERW) or submerged arc welding (SAWL) processes, this straight seam welded steel pipe boasts a minimum yield strength of 690 MPa, a significant improvement over the 551 MPa of conventional X80 steel pipe, providing a new material solution for long-distance, high-pressure transportation.
First, the breakthrough in materials science for X100M straight seam welded steel pipe.
The core advantage of X100M straight seam welded steel pipe lies in its innovative alloy design. By utilizing Nb-Ti-Mo composite microalloying technology, combined with the controlled rolling and controlled cooling (TMCP) process, the steel plate achieves both fine-grain strengthening and precipitation strengthening while maintaining excellent weldability. Leading domestic companies such as Baosteel have achieved low-temperature toughness of over 200J of impact energy at -45°C for an 18.4mm thick X100M steel plate, far exceeding the DNV-OS-F101 standard for Arctic pipelines. Notably, modern metallurgical technology, through calcium treatment to improve sulfide morphology, has enabled the pipe’s Z-axis performance coefficient to exceed 0.8, effectively addressing the industry’s challenge of lamellar tearing in large-diameter steel pipes.
Secondly, precise control of the manufacturing process for X100M straight-seam welded steel pipes. During pipemaking, leading domestic companies such as Zhujiang Steel Pipe utilize the JCOE forming process, which enables ovality control of ±0.5%D for pipes with a diameter of 1422mm and a wall thickness of 32mm. Multi-wire submerged arc welding (up to five wires in series) is employed during welding, combined with online ultrasonic testing and full pipe expansion (1.5% strain), resulting in a weld coefficient exceeding 0.96. Field test data from a West-East Gas Pipeline III project shows that the weld fatigue life of X100M welded steel pipe reaches 92% of that of the base metal, nearly 40% higher than that of traditional X70 welded steel pipe. The application of a digital factory further enables 0.1mm-level precision control throughout the entire process, from plate edge milling to pipe end chamfering.
Third, the revolutionary value of X100M straight seam welded steel pipe in engineering applications.
In the Central Asia Natural Gas Pipeline Project, the use of X100M straight seam steel pipe increased the design pressure from 12 MPa for X80 steel pipe to 15 MPa, increasing the annual gas transmission capacity of a single pipe by 25% while reducing wall thickness by 14%, directly saving 80,000 tons of steel (based on a 300-kilometer pipeline). More notably, its strain hardening exponent (n value) reaches 0.12, allowing it to withstand 1.5% plastic deformation without failure in an 8-magnitude seismic zone. Simulation tests conducted by the research institute show that using X100M steel for a 3,000-kilometer pipeline could reduce maintenance costs by $320 million over its entire lifecycle.
Fourth, the coordinated evolution of the standard system for X100M straight seam welded steel pipe.
With the implementation of the 46th edition of the API SPEC 5L standard, the technical requirements for X100M have become a complete system. The shear area ratio requirement for the DWTT (Drop Weight Tearing Test) at -15°C is ≥85%, a 10 percentage point improvement over X80 steel. The domestic GB/T 9711-2017 standard innovatively adds a solution A standard for the HIC (Hydrogen Induced Cracking) test, requiring a CLR (Crack Length Ratio) of ≤15%. These stringent standards have driven manufacturers to develop low-carbon welding formulas with a carbon equivalent (CEIW) of ≤0.43%, significantly reducing the susceptibility of girth welds to cold cracking in the field.
Fifth, a breakthrough in the environmental adaptability of X100M straight seam welded steel pipe.
To meet the unique needs of the Arctic region, the newly developed X100M steel pipe maintains a CVN (Charpy Impact) energy of >100J at -60°C. The X100M pipe used in the Arctic 2 project innovatively utilizes a dual-layer 3LPE+PP corrosion protection system. Combined with cathodic protection, this system extends its design life to 50 years. In marine environments, the addition of a corrosion-resistant alloy containing 0.3% Cu and 0.05% Sb keeps the corrosion rate in the splash zone below 0.08 mm/year, just one-fifth that of conventional carbon steel.
Sixth, Technical Challenges Across the Entire Industry Chain for X100M Longitudinal Welded Steel Pipe
Despite its significant advantages, X100M straight seam steel pipe still faces numerous challenges in its industrialization. Softening in the heat-affected zone (HAZ) causes the hardness of some weld end zones to drop below 220 HV10. Currently, post-weld induction heating technology can reduce the hardness to around 245 HV10. Another challenge lies in on-site girth welding, requiring the development of welding wire with a heat input below 80 kJ/cm2. For example, Kobelco’s MG-S63TW welding consumables have achieved excellent performance with an impact energy of >47 J at -40°C. Third-party testing data shows that the CTOD (crack tip opening displacement) of X100M girth welds using the automated welding process can reach 0.25mm, fully meeting the stringent requirements of the BS7910 standard.
As the “dual carbon” strategy advances, X100M straight seam steel pipe will demonstrate even greater value in the CCUS (carbon capture and storage) sector. Its pressure-bearing capacity supports supercritical CO2 transport exceeding 15 MPa and has been successfully applied in the Canadian Quest project. Domestic research and development institutions are exploring the suitability of X100M steel pipe in extreme environments with 90% H2S and 10% CO2. Preliminary tests have shown that by reducing the Mn content to below 1.2% and adding 0.02% Ti, the critical stress for SSC (sulfide stress corrosion) can be increased to 85% SMYS. These breakthroughs will make X100M straight seam steel pipe a core material for next-generation energy infrastructure, with global annual demand expected to exceed 3 million tons by 2030.
Post time: Aug-08-2025