Steel pipe
Steel pipe has hollow section and its length is much larger than the diameter or circumference of steel. According to the section shape, it is divided into circular, square, rectangular and special-shaped steel pipes; According to the material, it is divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe; It is divided into steel pipes for transmission pipeline, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high-pressure equipment, etc; According to the production process, it is divided into seamless steel pipe and welded steel pipe. Seamless steel pipe is divided into hot rolling and cold rolling (drawing), and welded steel pipe is divided into straight seam welded steel pipe and spiral seam welded steel pipe.
Steel pipe is not only used for conveying fluid and powdery solids, exchanging heat energy, manufacturing mechanical parts and containers, but also an economic steel. Using steel pipe to make building structure grid, pillar and mechanical support can reduce weight, save metal by 20 ~ 40%, and realize industrialized and mechanized construction. Manufacturing Highway Bridges with steel pipes can not only save steel and simplify construction, but also greatly reduce the area of protective coating and save investment and maintenance costs. By production method
Steel pipes can be divided into two categories according to production methods: seamless steel pipes and welded steel pipes. Welded steel pipes are referred to as welded pipes for short.
1. Seamless steel pipe can be divided into hot rolled seamless pipe, cold drawn pipe, precision steel pipe, hot expanded pipe, cold spinning pipe and extruded pipe according to the production method. Bundles of steel pipes Seamless steel pipe is made of high-quality carbon steel or alloy steel, which can be divided into hot rolling and cold rolling (drawing). 2. Welded steel pipe is divided into furnace welded pipe, electric welding (resistance welding) pipe and automatic arc welded pipe due to different welding processes. Due to different welding forms, it is divided into straight seam welded pipe and spiral welded pipe. Due to its end shape, it is divided into circular welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded steel pipe is made of rolled steel plate welded by butt joint or spiral seam. In terms of manufacturing method, it is also divided into welded steel pipe for low-pressure fluid transmission, spiral seam welded steel pipe, direct rolled welded steel pipe, welded steel pipe, etc. Seamless steel pipe can be used for liquid and gas pipelines in various industries. Welded pipes can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc. By material Steel pipe can be divided into carbon pipe, alloy pipe, stainless steel pipe, etc. according to pipe material (i.e. steel grade). Carbon pipe can be divided into ordinary carbon steel pipe and high-quality carbon structural pipe. Alloy pipe can be divided into: low alloy pipe, alloy structure pipe, high alloy pipe and high strength pipe. Bearing pipe, heat and acid resistant stainless pipe, precision alloy (such as kovar alloy) pipe and superalloy pipe, etc. Welded steel pipe, also known as welded pipe, is a steel pipe welded with steel plate or steel strip after crimping. Welded steel pipe has the advantages of simple production process, high production efficiency, many varieties and specifications and less equipment investment, but its general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the progress of welding and inspection technology, the weld quality has been continuously improved, the varieties and specifications of welded steel pipes have been increasing, and seamless steel pipes have been replaced in more and more fields. Welded steel pipes are divided into straight welded pipe and spiral welded pipe according to the form of weld. Longitudinal welded pipe has the advantages of simple production process, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight welded pipe. It can produce welded pipe with larger pipe diameter with narrow blank, and welded pipe with different pipe diameter with blank of the same width. However, compared with the straight seam pipe with the same length, the weld length increases by 30 ~ 100%, and the production speed is low. Therefore, straight seam welding is mostly used for small-diameter welded pipes, and spiral welding is mostly used for large-diameter welded pipes. Welded steel pipe for low pressure fluid transmission (GB / t3091-2008) is also known as general welded pipe, commonly known as black pipe. It is a welded steel pipe used for conveying water, gas, air, oil, heating steam and other general low pressure fluids and other purposes. The wall thickness of steel pipe connection is divided into ordinary steel pipe and thickened steel pipe; The nozzle end is divided into non threaded steel pipe (smooth pipe) and threaded steel pipe. The welded steel pipe for low-pressure fluid transmission is not only directly used for fluid transmission, but also widely used as the original pipe of galvanized welded steel pipe for low-pressure fluid transmission. 1. Galvanized welded steel pipe for low-pressure fluid transmission (GB / t3091-2008) is also known as galvanized welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welding or electric welding) steel pipe used for conveying water, gas, air oil, heating steam, heating water and other general low pressure fluids or other purposes. The wall thickness of steel pipe connection is divided into ordinary galvanized steel pipe and thickened galvanized steel pipe; The nozzle end is divided into non threaded galvanized steel pipe and threaded galvanized steel pipe. The specification of steel pipe is expressed in nominal diameter (mm), which is the approximate value of inner diameter. It is customary to use inches, such as 1 / 2, 3 / 4, 1, 2, etc. 2. ordinary carbon steel wire sleeve (Yb / t5305-2006) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings and installation of machinery and equipment. 3. Straight seam electric welded steel pipe (GB / t13793-2008) is a steel pipe whose weld is longitudinally parallel to the steel pipe. For general structure, it is usually divided into metric welded steel pipe, welded thin-wall pipe, etc. 4. Spiral seam submerged arc welded steel pipe (SY / t5037-2000) for pressure fluid transmission is a spiral seam steel pipe used for pressure fluid transmission, which takes hot-rolled steel strip coil as pipe blank, often warm spiral forming and double-sided submerged arc welding. The steel pipe has strong pressure bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The steel pipe has large diameter and high transmission efficiency, and can save the investment in laying pipelines. The pipeline is mainly used for transporting oil and natural gas. 5. Spiral seam high-frequency welded steel pipe (SY / t5038-2000) for pressure fluid transportation is a spiral seam high-frequency welded steel pipe for pressure fluid transportation, which takes hot-rolled steel strip coil as pipe blank, often warm spiral forming and high-frequency lap welding method. The steel pipe has strong pressure bearing capacity and good plasticity, which is convenient for welding and processing; After various strict and scientific inspections and tests, the utility model has the advantages of safe and reliable use, large diameter of steel pipes, high transmission efficiency, and saving investment in laying pipelines. It is mainly used for laying pipelines for transporting oil, natural gas, etc. 6. Spiral seam high-frequency welded steel pipe for general low-pressure fluid transportation (SY / t5039-2000) takes hot-rolled steel strip coil as pipe blank, often warm spiral forming, and uses high-frequency lap welding method to weld spiral seam high-frequency welded steel pipe for general low-pressure fluid transportation. 7. Spiral welded steel pipe for pile (SY / t5768-2000) is made of hot-rolled steel strip coil as pipe blank, often warm spiral forming, and made of double-sided submerged arc welding or high-frequency welding. It is used for steel pipe for foundation pile of civil building structure, wharf, bridge and so on.