The anticorrosion of buried steel pipes is the key procedure to ensure and prolong their service life. In order to ensure that the anti-corrosive insulation layer is firmly combined with the pipe wall, the most important thing is the derusting of the pipeline.
Generally, the rust on the surface of the American standard steel pipe can be divided into floating rust, medium rust and heavy rust according to the delivery time, storage and transportation conditions, and the degree of climate humidity.
Floating rust: Generally, when there is a short delivery date, and there is a small amount of thin rust on the surface of the tube when it is not stored in the open air, the metal luster can be exposed by manual operations such as wire brush, sandpaper and cotton yarn.
Medium rust and heavy rust: When the factory date is long and the open storage or multiple transfers and transportation are long, the surface of the tube is oxidized and rusted, and the rust spots are heavy. In severe cases, the scale is peeled off.
Severely corroded pipelines are not suitable for water delivery systems. For medium-rust pipes and large batches, rust removal machines or mechanical sandblasting can be used for mechanical derusting, which can improve labor efficiency and reduce pollution to people and air. .
When high corrosion resistance is required or the inner and outer walls of the pipe have been corroded, the chemical derusting method can be used to effectively remove the oxides on the inner and outer surfaces of the pipe.
No matter which method is used to remove rust, the anticorrosion layer should be treated immediately after the rust is removed to avoid being oxidized and corroded by the air again.
http://www.xysteelpipe.com/info/The-corrosion-protection-of-steel-pipes-is-closely-related-to-the-service-life-1667-1.htm
2020年5月6日星期三
Production of cold-drawn precision seamless steel tube
1. Hair management. The wall thickness of the capillary should be uniform, with fewer defects on the inner and outer surfaces. Equipment for polishing external surfaces and cleaning internal hole defects shall be provided.
2. Review. In the production of cold drawn precision seamless steel tubes, compared with ordinary cold drawn steel tubes, hot rolling capillary pickling and re-inspection processes are added. This is to ensure that there are no defects such as folds and cracks on the outer surface of the capillary, and to eliminate defects such as folds, severe marking and linen surface on the inner surface of the capillary.
3. Tools. The surface finish of the tools used in the production of cold-drawn precision seamless steel tubes should be controlled. At the same time, the head or mould is prevented from being stuck during the drawing process.
4. The production process of cold-rolled seamless steel pipe is generally more complicated than that of hot-rolling. If the surface does not respond to cracks, the round pipe is cut and cut into a billet with a length of about one meter. Annealing is a very important part in the production process of cold drawn steel pipes. The quality of annealing not only affects the performance of the steel pipe, but also affects the removal of scale.
5. In the pickling process of precision seamless steel tubes, black slag is easily formed, and in subsequent production, black spots will form on the surface. Black residue is easily soluble in hydrochloric acid. In order to prevent the formation of black spots, hydrochloric acid should be added to the acid tank.
6. Resin should be used as lubricant. Compared with phosphating and lubrication, lubrication has obvious differences. The drawn steel pipe has the characteristics of an iron matrix, which not only has high finish, but also has the beautiful appearance of cold-rolled steel pipe.
2. Review. In the production of cold drawn precision seamless steel tubes, compared with ordinary cold drawn steel tubes, hot rolling capillary pickling and re-inspection processes are added. This is to ensure that there are no defects such as folds and cracks on the outer surface of the capillary, and to eliminate defects such as folds, severe marking and linen surface on the inner surface of the capillary.
3. Tools. The surface finish of the tools used in the production of cold-drawn precision seamless steel tubes should be controlled. At the same time, the head or mould is prevented from being stuck during the drawing process.
4. The production process of cold-rolled seamless steel pipe is generally more complicated than that of hot-rolling. If the surface does not respond to cracks, the round pipe is cut and cut into a billet with a length of about one meter. Annealing is a very important part in the production process of cold drawn steel pipes. The quality of annealing not only affects the performance of the steel pipe, but also affects the removal of scale.
5. In the pickling process of precision seamless steel tubes, black slag is easily formed, and in subsequent production, black spots will form on the surface. Black residue is easily soluble in hydrochloric acid. In order to prevent the formation of black spots, hydrochloric acid should be added to the acid tank.
6. Resin should be used as lubricant. Compared with phosphating and lubrication, lubrication has obvious differences. The drawn steel pipe has the characteristics of an iron matrix, which not only has high finish, but also has the beautiful appearance of cold-rolled steel pipe.
Common Materials of ERW Welded Pipe
Common materials for welded pipes are: Q235A, Q235C, Q235B, 16Mn, 20 #, Q345, L245, L290, X42, X46, X60, X80, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc.
The blank used for welded steel pipe is steel plate or strip steel, which is divided into furnace welded pipe, electric resistance welded pipe and automatic arc welded pipe due to different welding processes. Because of its different welding forms, it is divided into two types: straight seam welded pipe and spiral welded pipe. Because of its end shape, it is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded pipes are divided into the following varieties due to their different materials and uses:
GB / T3091-2008 (welded steel pipe for low-pressure fluid transportation): mainly used for conveying water, gas, air, oil and heating hot water or steam and other generally low-pressure fluid and other use pipes. Its representative material is: Q235A grade steel.
GB / T14291-2006 (Welding Steel Pipe for Mine Fluid Transportation): Mainly used for straight seam welded steel pipes for mine pressure, drainage and shaft gas discharge. Its representative material is Q235A, B grade steel.
GB / T12770-2002 (stainless steel welded steel pipe for mechanical structure): mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb and so on.
GB / T12771-1991 (stainless steel welded steel pipe for fluid transportation): mainly used to transport low-pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.
In addition, welded stainless steel pipes for decoration (GB / T 18705-2002), welded stainless steel pipes for building decoration (JG / T 3030-1995), and welded steel pipes for heat exchangers (YB4103-2000).
The blank used for welded steel pipe is steel plate or strip steel, which is divided into furnace welded pipe, electric resistance welded pipe and automatic arc welded pipe due to different welding processes. Because of its different welding forms, it is divided into two types: straight seam welded pipe and spiral welded pipe. Because of its end shape, it is divided into round welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded pipes are divided into the following varieties due to their different materials and uses:
GB / T3091-2008 (welded steel pipe for low-pressure fluid transportation): mainly used for conveying water, gas, air, oil and heating hot water or steam and other generally low-pressure fluid and other use pipes. Its representative material is: Q235A grade steel.
GB / T14291-2006 (Welding Steel Pipe for Mine Fluid Transportation): Mainly used for straight seam welded steel pipes for mine pressure, drainage and shaft gas discharge. Its representative material is Q235A, B grade steel.
GB / T12770-2002 (stainless steel welded steel pipe for mechanical structure): mainly used for machinery, automobiles, bicycles, furniture, hotel and restaurant decoration and other mechanical parts and structural parts. Its representative materials are 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb and so on.
GB / T12771-1991 (stainless steel welded steel pipe for fluid transportation): mainly used to transport low-pressure corrosive media. Representative materials are 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc.
In addition, welded stainless steel pipes for decoration (GB / T 18705-2002), welded stainless steel pipes for building decoration (JG / T 3030-1995), and welded steel pipes for heat exchangers (YB4103-2000).
Fire prevention measures for seamless steel tube
At present, seamless steel tube construction is increasing, especially in some buildings, the use of seamless steel tube materials is more widespread. Once a fire accident occurs in a building, the fire cannot be extinguished in a short period of time. This requires us to design the building to provide fire protection to the building materials to enhance their fire resistance, and to formulate the necessary emergency plan inside the building to reduce Casualties and property damage. So, what are the fire protection measures for seamless steel tubes?
1. Outer cladding. It is to add an outer cladding on the surface of the seamless steel tube, which can be cast-in-place or sprayed. The cast-in-situ molded solid concrete outer cladding is usually strengthened with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the seamless steel pipe at the construction site to form a layer. The sand pump can be lime cement or gypsum mortar, or can be mixed with perlite or asbestos. At the same time, the outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, and light concrete into prefabricated panels, which are fixed on seamless steel pipes with adhesives, nails, and bolts.
2. Fill with water. Straight seam steel pipes are steel pipes with welds parallel to the longitudinal direction of the steel pipe. Usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling oil pipes, etc. Straight seam welded pipe production process is simple, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters. Filling the hollow seamless steel pipe with water is an effective protective measure against fire. This method can keep the seamless steel pipe at a low temperature in the fire, water circulates in the seamless steel pipe, and absorbs the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced through pipes to replace the heated water.
3. Shield. Precision steel pipe is a kind of high-precision steel pipe material processed by cold drawing or hot rolling. Because the inner and outer walls of the precision steel pipe have no oxide layer, withstand high pressure without leakage, high precision, high finish, cold bending without deformation, flaring, flattening and no crack, etc., it is mainly used to produce products for pneumatic or hydraulic components, such as cylinder Cylinders can be seamless or welded. The seamless steel pipe is installed in the wall or ceiling made of refractory materials, or the components are hidden in the gap between the two walls. As long as a little refractory material is added or not added, the purpose of fire prevention can be achieved. This is a very economical method of fire prevention.
4. Expansion materials. The use of seamless steel tube fireproof coating components, this method has the advantages of good fire insulation performance, construction is not limited by the geometric shape of the seamless steel tube, etc., generally do not add auxiliary facilities, and the coating quality is light, and also has a certain decorative effect, It belongs to modern advanced fire prevention technical measures.
http://www.xysteelpipe.com/info/Fire-prevention-measures-for-seamless-steel-tube-1666-1.htm
1. Outer cladding. It is to add an outer cladding on the surface of the seamless steel tube, which can be cast-in-place or sprayed. The cast-in-situ molded solid concrete outer cladding is usually strengthened with steel wire mesh or steel bars to limit shrinkage cracks and ensure the strength of the shell. The spraying method can apply a sand pump to the surface of the seamless steel pipe at the construction site to form a layer. The sand pump can be lime cement or gypsum mortar, or can be mixed with perlite or asbestos. At the same time, the outer cladding can also be made of perlite, asbestos, gypsum or asbestos cement, and light concrete into prefabricated panels, which are fixed on seamless steel pipes with adhesives, nails, and bolts.
2. Fill with water. Straight seam steel pipes are steel pipes with welds parallel to the longitudinal direction of the steel pipe. Usually divided into metric welded steel pipes, welded thin-walled pipes, transformer cooling oil pipes, etc. Straight seam welded pipe production process is simple, high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters. Filling the hollow seamless steel pipe with water is an effective protective measure against fire. This method can keep the seamless steel pipe at a low temperature in the fire, water circulates in the seamless steel pipe, and absorbs the heat of the material itself. The heated water can be recirculated after cooling, or cool water can be introduced through pipes to replace the heated water.
3. Shield. Precision steel pipe is a kind of high-precision steel pipe material processed by cold drawing or hot rolling. Because the inner and outer walls of the precision steel pipe have no oxide layer, withstand high pressure without leakage, high precision, high finish, cold bending without deformation, flaring, flattening and no crack, etc., it is mainly used to produce products for pneumatic or hydraulic components, such as cylinder Cylinders can be seamless or welded. The seamless steel pipe is installed in the wall or ceiling made of refractory materials, or the components are hidden in the gap between the two walls. As long as a little refractory material is added or not added, the purpose of fire prevention can be achieved. This is a very economical method of fire prevention.
4. Expansion materials. The use of seamless steel tube fireproof coating components, this method has the advantages of good fire insulation performance, construction is not limited by the geometric shape of the seamless steel tube, etc., generally do not add auxiliary facilities, and the coating quality is light, and also has a certain decorative effect, It belongs to modern advanced fire prevention technical measures.
http://www.xysteelpipe.com/info/Fire-prevention-measures-for-seamless-steel-tube-1666-1.htm
2020年5月5日星期二
Process characteristics of spiral steel tube
Spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, and urban construction. It is one of the twenty key products developed.
For liquid transportation: water supply and drainage.
For gas transportation: coal gas, steam, liquefied petroleum gas.
For structural use: for piling pipes and bridges; for docks, roads, and building structures.
Main technical characteristics of spiral steel pipe:
1. During the forming process, the steel plate deforms uniformly, the residual stress is small, and the surface is not scratched. The processed spiral steel pipe has more flexibility in the range of diameter and wall thickness. Especially in the production of small and medium-diameter thick-walled pipes, it has advantages that are unmatched by other processes, and can meet the user's more requirements on spiral steel pipe specifications .
2. Adopting advanced double-sided submerged arc welding technology, welding can be achieved in a good position, which is not prone to defects such as misalignment, welding deviation and under-welding, and it is easy to control welding quality.
3, 100% quality inspection of steel pipes, so that the entire process of steel pipe production under effective detection and monitoring, effectively guarantee product quality.
4. All the equipment of the whole production line has the function of networking with computer data acquisition system, real-time data transmission, and the central control room controls the technical parameters in the production process.
5. The raw materials are strip coil, welding wire and flux. Before input, it must undergo strict physical and chemical tests.
6. Strip steel head and tail butt joint, using single wire or double wire submerged arc welding, after coiling into steel pipe, automatic submerged arc welding machine repair welding.
7. Before forming, the strip is subjected to leveling, trimming, planing, surface cleaning and pre-bending.
8. The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveyance of the strip.
9.Using external control or internal control roll forming.
10. Weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.
For liquid transportation: water supply and drainage.
For gas transportation: coal gas, steam, liquefied petroleum gas.
For structural use: for piling pipes and bridges; for docks, roads, and building structures.
Main technical characteristics of spiral steel pipe:
1. During the forming process, the steel plate deforms uniformly, the residual stress is small, and the surface is not scratched. The processed spiral steel pipe has more flexibility in the range of diameter and wall thickness. Especially in the production of small and medium-diameter thick-walled pipes, it has advantages that are unmatched by other processes, and can meet the user's more requirements on spiral steel pipe specifications .
2. Adopting advanced double-sided submerged arc welding technology, welding can be achieved in a good position, which is not prone to defects such as misalignment, welding deviation and under-welding, and it is easy to control welding quality.
3, 100% quality inspection of steel pipes, so that the entire process of steel pipe production under effective detection and monitoring, effectively guarantee product quality.
4. All the equipment of the whole production line has the function of networking with computer data acquisition system, real-time data transmission, and the central control room controls the technical parameters in the production process.
5. The raw materials are strip coil, welding wire and flux. Before input, it must undergo strict physical and chemical tests.
6. Strip steel head and tail butt joint, using single wire or double wire submerged arc welding, after coiling into steel pipe, automatic submerged arc welding machine repair welding.
7. Before forming, the strip is subjected to leveling, trimming, planing, surface cleaning and pre-bending.
8. The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveyance of the strip.
9.Using external control or internal control roll forming.
10. Weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, misalignment and weld gap are strictly controlled.
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