Q235B LSAW Steel Pipe DN400

Q235B LSAW steel pipe DN400: the core supporting pipe for small and medium-sized projects.

Q235B LSAW steel pipe DN400 (nominal diameter of 400mm, corresponding to external diameter of about 426mm) is a key pipe made of Q235B carbon structural steel and longitudinal submerged arc welding technology, which conforms to GB/T 9711 and GB/T 700-2024 standards, has both transportation efficiency, structural reliability and high cost performance, and is the core product for connecting small and medium-sized transportation scenes, and is of great significance to promoting municipal construction, industrial support, civil security and other fields. Its core value lies in meeting the needs of mid-range large-scale transportation with the characteristics of economic adaptation, and filling the gap between DN350 and DN450. This paper analyzes its characteristics, significance and application value with the subtitle of question sentence.

1. Material adaptation: Can Q235B meet the requirements of DN400?

It's completely adaptable. Q235B, as a common carbon structural steel, has a yield strength of ≥235MPa, a tensile strength of 370-500MPa, and an elongation at break of ≥26%, and can stably withstand the pressure of 8-10MPa, which meets the medium and low pressure requirements of DN400. The carbon content of this material is less than or equal to 0.20%, and it has excellent plasticity and toughness, and is easy to weld and process. It can meet the welding requirements of LSAW without complicated process, and the raw materials are easily available and the cost is low, which is more than 20% lower than that of Q355B pipes with the same specification, and the precise adaptation of working conditions is realized with high cost performance.

2. Specification process: How to balance the conveying efficiency and structural stability?

Compared with DN350, the transportation efficiency of DN400 is improved by 20%, which can meet the large-scale demand of centralized energy supply and industrial auxiliary transportation in the area and avoid the high cost and construction pressure of large diameter. LSAW longitudinal submerged arc welding process is adopted, and precision forming technology is used. The weld strength is close to the base metal, and the stress distribution is uniform. After forming, the residual stress is eliminated by quenching and tempering treatment, and the outer diameter tolerance is controlled within 0.6%, which ensures the long-term structural stability of various laying methods such as underground and open air.