Seamless pipes are made from tube blanks of various specifications through high-temperature extrusion, cooling, annealing, finishing and other processes. It is one of the four major construction steel varieties in my country. It is mainly used for transporting fluids such as water, oil, natural gas, coal, etc. and for pipes in building structures. It can also be used to manufacture carbon structures in heavy industrial sectors such as automobiles, tractors, hydraulic equipment, and mining machinery. Pipes and alloy structural pipes. Seamless steel pipes are widely used in petroleum, chemical industry, electric power, shipbuilding, aerospace, nuclear industry, national defense construction and other fields. Seamless steel pipe has a hollow section, which can reduce the cohesion of the material, thereby reducing friction; at the same time, it has good thermal conductivity and thermal conductivity, so it is also widely used in manufacturing automobiles, tractors, hydraulic equipment, mechanical processing, etc. External wall pipes and oil pipes for industrial machinery and equipment.
1. Seamless pipes can be processed according to different requirements and are widely used in manufacturing structural parts and mechanical parts.
For example, automobile engines and transmission systems are high-precision parts with special purposes. They must have good accuracy to meet design requirements. In the automotive industry, automobile steering gears are often affected by harsh working conditions. The quality of the steering system requires high precision. Therefore, the manufacturing of such high-precision parts is very difficult. After years of development, our country can now produce high-precision seamless steel pipes.
2. The production methods of seamless pipes can be divided into hot-rolled, cold-rolled or cold-drawn (extruded) steel pipes, which can be processed into appropriate lengths according to user needs.
Materials can be divided into: carbon structural steel pipes, alloy steel or stainless steel, copper and other non-ferrous metal structural metal pipes and non-precious metal steel pipes; according to different uses, they can be further divided into: petroleum cracking pipes, conveying fluid pipes, chemical steel pipes , structural steel pipes, high-pressure boiler pipes and special-purpose seamless steel pipes made of non-precious or steel materials, etc. The working temperature range of 20# seamless steel pipe is between -40~350℃; according to its chemical composition, it can be divided into amorphous carbon structural pipe blank and rolled seamless round pipe. Commonly used varieties of seamless round pipes include: carbon structural pipes (such as oil drill pipes, automobile transmission shafts, etc.), alloy structural pipes (such as high-pressure fertilizer steel pipes, petroleum cracking steel pipes, high-pressure boiler steel pipes, etc.), low alloy steel pipes and special steel pipes. Purpose steel pipes, etc.; according to chemical composition, they can be divided into acid-resistant seamless steel pipes; according to shape and size, they can be divided into square tubes, round tubes, rectangular tubes, and special-shaped tubes.
The market demand for pipeline seamless steel pipes has weakened. In terms of inventory: domestic steel mills are destocking quickly, but there is also a certain inventory pressure. In addition, due to the impact of environmental protection and production restriction policies, the contradiction between market supply and demand is not prominent, and the room for price increases is limited.
3. Seamless pipes can be formed by hot rolling or cold drawing and then welded.
When using seamless steel pipes for mechanical processing, they must be processed according to the specifications, dimensions, methods and materials specified in the drawings, and surface treatment should be carried out according to regulations before welding. Direct arc welding is not allowed. The heat generated when the arc heat is large may melt the weld metal and reduce the quality of the weld. Before welding, the quality of the weld must be carefully checked and non-destructive testing must be carried out. When there are defects on the welds, no flaw detection inspection is allowed and non-destructive testing equipment should be used; when there are continuous defects on the welds, no flaw detection inspections are allowed; when there are continuous cracks on the welds, no flaw detection inspections are allowed; when there are continuous cracks on the welds No flaw detection inspection is allowed. When serious defects occur, welding should be stopped immediately and repair welding should be performed.