The use and classification of seamless steel pipes
Seamless steel pipes are widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycle frames and steel scaffolding used in construction. The material and processing time have been widely used in the manufacture of steel pipes.
A steel pipe without seams along the perimeter of its cross-section. According to different production methods, it is divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking, etc., all of which have their own process regulations. The materials are ordinary and high-quality carbon structural steel (Q215-A~Q275-A and 10~50 steel), low alloy steel (09MnV, 16Mn, etc.), alloy steel, stainless acid-resistant steel, etc. According to the use, it is divided into two categories: general use (for water, gas pipelines and structural parts, mechanical parts) and special (for boilers, geological exploration, bearings, acid resistance, etc.).
The performance of seamless steel pipe
Seamless steel pipe is a widely used steel in the electric power industry. It has high thermal strength when used at 500℃-550℃. When the operating temperature is higher than 550 °C, its thermal strength performance is significantly reduced. Generally, seamless steel pipes are mainly used for high and medium pressure pipes with steam parameters of 510 °C, steam guide pipes, and heat exchanger tubes with a tube wall temperature of 550 °C.
The microstructure of the seamless steel pipe in the normal supply state is ferrite and pearlite. During the long-term operation of the seamless steel pipe in the working temperature range of 500 ° C – ° C, the spheroidization of pearlite, alloying elements in solid solution and carbide will occur. Due to the redistribution between the two parts and the change of the carbide phase structure, the thermal strength and mechanical properties of the seamless steel pipe gradually decrease with the increase of the degree of pearlite spheroidization and the degree of depletion of alloying elements in the solid solution, so that the material gradually deteriorates or even deteriorates. invalid. Therefore, for a long time, the degree of pearlite spheroidization in the microstructure of seamless steel pipes has been widely used as one of the important criteria for judging the reliability of this type of steel.
The seamless steel pipe can meet the requirements of the sewage system in the city
At present, with the rapid economic development, urbanization is becoming more and more common. With the establishment of high-rise buildings in the city, various problems are also increasing. Among them, sewage treatment is a major problem in urban construction. Every day, cities produce more sewage due to industrial production and people’s daily life. These sewage will be processed through the sewage pipes in the city. In the construction of environmental treatment projects, the sewage system often occupies a large proportion of investment. The pipes used in the sewage system are not ordinary steel pipes, but seamless steel pipes, because only seamless steel pipes can meet the requirements of the sewage system.
The corrosion resistance of seamless steel pipes is very good, because seamless steel pipes will also be tested for corrosion resistance during processing. It is to put the pipeline into the acid solution for performance testing. In this way, the discharge of acidic or alkaline substances in the sewage can be satisfied. This ensures the safety of the urban drainage system and the normal operation of all aspects of the city.