Carbon steel pipe: an important carrier for industrial transportation and structure

Carbon steel pipe is a tubular profile made from carbon steel with a carbon content of 0.0218%-2.11% through rolling, forming, welding, or seamless processing. Due to its reliable material and easy processing, it has become a core material in the fluid transportation and structural support sectors, widely applicable to various applications such as industry, construction, and municipal administration.

Based on its core attributes, it can be further categorized into seamless carbon steel pipe and welded carbon steel pipe. Seamless pipe is manufactured through processes such as hot rolling, piercing, and cold drawing. It has no welds and offers high pressure resistance, making it suitable for high-pressure applications. Welded pipe is formed by rolling steel plate and then welding it. It includes straight seam welded pipe (with the weld running along the axis) and spiral welded pipe (with the weld forming a spiral). It offers lower production costs and is suitable for medium and low-pressure applications. By carbon content, these pipes include low-carbon steel pipe (carbon content ≤ 0.25%, good ductility and easy welding), medium-carbon steel pipe (0.25%-0.6%, higher strength), and high-carbon steel pipe (>0.6%, high hardness but poor ductility, mostly used in wear-resistant structural parts), adapting to different load-bearing and processing requirements.

Their core characteristics focus on "functional adaptability": Seamless carbon steel pipes, free of weld defects, offer outstanding tensile strength and pressure resistance. They can withstand pressures of 10-30 MPa at room temperature, making them suitable for transporting high-pressure fluids such as oil and natural gas. While welded pipes offer slightly lower pressure resistance (typically ≤ 10 MPa), they offer high production efficiency and a wide range of pipe diameters (from DN15 to DN3000 and above). Spiral welded pipes, in particular, offer superior crack resistance to straight seam welded pipes due to stress distribution through the weld seam, making them suitable for large-diameter water supply and drainage, and municipal gas transportation. Carbon steel pipes also maintain their cost advantages, costing only 1/4-1/2 of stainless steel pipes. Furthermore, corrosion resistance can be enhanced through treatments like galvanizing and painting, making them highly cost-effective in less corrosive environments.

Application scenarios cover core needs across multiple sectors: In the fluid transport sector, seamless carbon steel pipes are used for high-pressure process piping in the petroleum and chemical industries, while spirally welded pipes are used for long-distance natural gas and water transportation. In the structural support sector, low-carbon steel pipes are bent and welded to form steel structure brackets and mechanical drive shafts, while medium-carbon steel pipes are used for load-bearing columns in heavy equipment. Furthermore, in fire protection systems, galvanized carbon steel pipes are a common choice for sprinkler pipes due to their rust resistance and pressure resistance. There are three key points to consider when using pipes: First, anti-corrosion treatment. Ungalvanized carbon steel pipes are prone to rusting in humid environments, so the coating integrity should be regularly inspected. For outdoor or underground pipes, a 3PE anti-corrosion coating (polyethylene + adhesive + epoxy powder) is recommended to enhance weather resistance. Second, pressure matching: Select pipes suitable for the process according to the pressure of the conveying medium. Welded pipes should not be used in place of seamless pipes for high-pressure applications. A hydrostatic test (test pressure 1.5 times the operating pressure) must be performed after installation. Third, welding quality: welded pipes must undergo X-ray or ultrasonic testing to prevent leaks caused by weld defects. Airtightness testing is also required when conveying flammable or explosive media.