Стальная труба: сердечник «полой стали» для промышленной транспортировки и поддержки конструкций

Steel pipes are hollow bars made from steel through processes such as rolling, welding, or forging. Their hollow structure reduces weight while providing a channel for media transport. They also possess excellent pressure-bearing, torsional, and corrosion-resistant properties, making them an irreplaceable component of energy transmission, construction, and machinery manufacturing. They are a typical "functional" steel material in industrial production.

I. Core Classification: Multi-Dimensional Classification to Meet Different Needs

(I) Production Process: Two Main Types

Seamless Steel Pipes: Seamless steel pipes are made from solid billets, heated to a plastic state in a furnace, then punched through a piercing mill to create a hollow billet. They are then rolled through a pipe mill multiple times to reduce the wall thickness and adjust the diameter. Finally, they are straightened by a sizing mill and cut by a pipe cutter. Because there are no weak points in the welds, its pressure-bearing capacity is extremely strong (it can withstand pressures of tens to hundreds of MPa). It is often used in high-pressure scenarios, such as deep-well oil and gas pipelines, heating surface pipes of power plant boilers, and oil pipes of high-pressure hydraulic systems. The material is mostly high-quality carbon steel (such as 20# steel) or alloy structural steel (such as 15CrMo steel). Welded steel pipe: Made from steel plate or strip, it is first rolled into round, square, or other cross-sections using a pipe reel. The joints are then welded together. Based on the weld seam configuration, it can be categorized into two types:

Straight seam welded pipe: The weld seam is parallel to the pipe axis, resulting in a quick production process and low cost. However, its pressure-bearing capacity is relatively low. It is primarily used for low-pressure water and gas pipelines (such as urban water pipes) and building scaffolding pipes. It is primarily made of ordinary carbon steel (such as Q235 steel).

Spiral seam welded pipe: The weld seam is distributed in a spiral pattern, distributing the load. Its strength is 30%-50% higher than that of straight seam welded pipe. Adjusting the spiral angle allows for the production of large-diameter steel pipes (up to 3 meters in diameter). This makes it suitable for long-distance, medium- and high-pressure oil and gas pipelines (such as portions of the West-East Gas Pipeline). (II) By Material: Adaptability to Different Environments

Carbon steel pipe: Primarily composed of iron and carbon, it offers low cost and strong versatility, accounting for over 70% of total steel pipe production and primarily used for general transportation and structural applications.

Alloy steel pipe: Contains elements such as chromium, molybdenum, and nickel to enhance its high-temperature, high-pressure, and wear-resistant properties. For example, chromium-molybdenum steel pipe is used for high-temperature steam pipelines, while nickel steel pipe is used for low-temperature LNG transportation.

Stainless steel pipe: Contains a chromium content of ≥10.5%, exhibits excellent corrosion resistance, and is commonly used in chemical acid and alkali pipelines, food processing pipelines, and medical equipment pipes (e.g., 304 stainless steel pipe).

II. Key Production Processes: Core Processes for Two Types of Steel Pipes

(I) Seamless Steel Pipes (Taking Hot-Rolled Seamless Pipes as an Example)

Bill Preparation: Round solid billets are selected and surface cleaned to remove scale and defects.

Heating and Piercing: The billets are fed into a ring-shaped heating furnace (1200-1300°C) and heated to a red-hot plastic state. They then enter a piercing mill, where they are punched through a tapered mandrel into thick-walled hollow tube billets (commonly known as "blanket tubes").

Rolling and Reducing: The blanket tubes enter a tube mill (such as a continuous tube mill) and are rolled through multiple sets of rollers, gradually reducing the wall thickness, lengthening the tubes, and adjusting the outer diameter.

Finishing: The outer diameter is calibrated in a sizing mill, then straightened and straightened. Finally, the tube cutters are cut to the required length. Some high-end seamless pipes also require flaw detection (such as ultrasonic testing) and heat treatment (to eliminate internal stresses). (II) Welded Steel Pipe (Taking Spiral Welded Pipe as an Example)
Raw Material Pretreatment: Steel plates or strips are flattened and trimmed to ensure uniform width, then passed through a rust remover to remove surface oxide scale.
Rolling: The pretreated plates are fed into a spiral coiler, where they are computer-controlled to form a circular tube at a set spiral angle while simultaneously adjusting the tube's roundness.
Welding Reinforcement: Submerged arc welding (with flux covering the weld to reduce oxidation) is used to secure the spiral seam, forming a continuous steel pipe.
Inspection and Cutting: Weld quality is inspected through ultrasonic testing, X-ray testing, and other methods, and defective products are removed. Finally, the pipes are cut to the required length. Some pipes also undergo anti-corrosion treatment (such as coating the outer surface with epoxy coal tar).

III. Main Application Areas: Covering Core Scenarios Across Multiple Industries

Energy Transportation: This is the largest application for steel pipes, accounting for over 40%. In addition to oil and gas transportation (spiral welded and seamless pipes), applications also include steam pipelines in the power industry (alloy seamless pipes), coolant pipelines in nuclear power plants (stainless steel seamless pipes), and pipes for photovoltaic racks in the new energy sector (thin-wall welded pipes).

Construction Engineering:

Structural Support: Steel columns for high-rise buildings, pipes for connecting subway tunnel segments (seamless pipes), and pipes for temporary bridge supports (straight seam welded pipes);

Decoration and Accessories: Stainless steel pipes for shopping mall handrails, corrosion-resistant welded pipes for building drainage pipes, and galvanized welded pipes for scaffolding (surface galvanizing enhances corrosion resistance).

Mechanical Manufacturing:

Transmission Components: Machine tool spindles, automotive drive shafts, and agricultural machinery gearbox shafts (seamless steel pipes, quenched and tempered for increased strength);

Hydraulics and Pneumatics: High-pressure oil pipes for hydraulic systems and air pipes for pneumatic equipment (precision seamless pipes with smooth inner surfaces to reduce medium resistance);

Container Components: Small pressure vessel cylinders (e.g., welded steel pipes for air compressor storage tanks).​
Consumer life and specialty applications: Household gas pipelines (thin-wall straight seam welded pipes), juice delivery pipes for food processing plants (316L stainless steel pipes), and tubes for medical surgical instruments (ultra-thin seamless stainless steel pipes, with diameters as small as 1 mm).

IV. Brief Development Trends: Technological Upgrades to Meet New Demands

Green Production: Promote short-process electric furnace steelmaking (using scrap steel as raw material, reducing carbon emissions by 50% compared to traditional converter steelmaking). Use lead-free solder and water-based anti-corrosion coatings in welded steel pipe production to reduce environmental pollution.

High-end Breakthroughs: Develop high-pressure seamless pipes for ultra-deep wells (capable of withstanding pressures exceeding 100 MPa, suitable for oil and gas wells over 5,000 meters deep) and deep-sea corrosion-resistant steel pipes (such as nickel-based alloy pipes, suitable for deep-sea oil and gas development) to meet the needs of extreme scenarios.

Intelligent Upgrades: Introducing AI visual inspection (real-time identification of steel pipe surface defects) and digital twin technology (simulating the rolling process to optimize parameters) into production lines to improve product precision and production efficiency.

Lightweight Innovation: Develop thin-walled, high-strength steel pipes (such as high-strength steel welded pipes) to reduce steel usage while maintaining strength, suitable for applications such as lightweighting automobiles and drone brackets.