1550x1550x80mm Heavy Wall Hollow Sections | Yuantai
In modern high-rise construction, cross-sea bridges, UHV transmission towers, and large wind turbine foundations, structural loads increase rapidly as project scale expands. As the primary load-bearing component, the performance and specifications of steel structures play a decisive role in the safety and service life of the entire project. When facing extreme loads, large-scale, heavy-wall hollow structural sections have become indispensable due to their superior torsional resistance and section modulus.
However, for a long period, conventionally available square and rectangular tubes in the international market were generally limited to sizes within 400×400 mm or 500×500 mm. This limitation was primarily imposed by traditional manufacturing processes. Many overseas mills favor the hot-finished process. Expanding the diameter and wall thickness further under this method demands exceptionally high furnace capacity and mill tonnage, which often leads to extended lead times and high production costs. On the other hand, if standard direct cold-forming is utilized, ultra-thick high-strength steel plates exhibit high yield strength, making the four corner regions highly susceptible to massive residual stress concentration and micro-cracking during the bending process.
This manufacturing constraint has frequently brought inconveniences to structural designs. For instance, at heavy-load nodes in airport terminals or massive industrial plants, due to the unavailability of ready-made, one-piece formed large square tubes, engineers often had to weld separate steel plates into built-up box sections, or splice multiple smaller tubes into complex assemblies. This approach not only incurred substantial on-site labor costs for welding and non-destructive testing but also increased long-term structural maintenance risks due to the high density of weld seams. The market has been consistently searching for one-piece formed sections with larger dimensions and heavier walls.
To meet these practical demands, Yuantai Derun has achieved a major breakthrough in product specifications through focused technical research and equipment upgrades. Today, Yuantai Derun's square and rectangular tubes can reach a maximum outer dimension of 1550×1550 mm, with a wall thickness of up to 80 mm.
This specification is the result of a systematic upgrade in manufacturing processes. Instead of relying on conventional direct forming, Yuantai Derun combines the advanced JCOE forming method with Round-to-Square technology. Production begins with ultra-heavy wall round pipes manufactured by high-tonnage JCOE forming and double-sided SAW. These are then converted into square and rectangular sections through controlled roll-forming stages. By spreading deformation more evenly throughout the material, this process minimizes corner cracking and avoids the uneven stress distribution typical of conventional methods when working with wall thicknesses as high as 80 mm.
Quality control relies on advanced non-destructive testing, including multi-channel automated ultrasonic and digital radiographic inspection, to achieve full-depth coverage of weld seams and heat-affected zones. Nevertheless, severe forming operations and high-heat welding inevitably result in high levels of residual stress in ultra-thick steel plates.To mitigate this, Yuantai Derun applies large-scale heat treatment for stress relief. By carefully controlling the heating, soaking, and cooling cycles, the steel’s microstructure is refined, removing over 90% of residual processing stress. This significantly improves the dimensional stability of large 1550 mm sections, while also enhancing fatigue performance and reducing the risk of hydrogen-induced cracking in service. In line with the fully implemented GB/T 6728-2025 standard, the tubes achieve strong international compatibility in both dimensional tolerances and mechanical properties.
Yuantai Derun, a national-level single-product champion manufacturer, is dedicated to the innovation and production of square and rectangular steel tubes. Its heavy-wall HSS solutions are applied in landmark buildings, heavy industry, and bridge construction, delivering reliable performance under stringent technical specifications worldwide.
