Chinese Machinery History

Seamless pipe production methods are many. Seamless steel pipe can be produced by hot rolling (about 80% ~ 90%) or cold rolling, cold drawing (about 10% ~ 20%) according to delivery requirements. There are round, square or polygon ingot, rolled billet or continuous casting billet for hot rolling tube. The quality of billet has a direct influence on the tube quality.
There are three basic processes for hot rolling pipes:
The ingots or billets are pierced into hollow thick-wall capillary tubes in the piercing machine;
The capillary is thinned in the extender to extend to a hollow tube with wall thickness;
The required finished pipe is made by rolling on the finishing mill. The series of pipe rolling mill is expressed by the maximum outside diameter of the pipe produced.
Methods of Manufacturing Seamless steel pipe:
(1) Automatic tube rolling production of seamless steel pipe one of the ways. The production equipment consists of piercing mill, automatic pipe rolling mill, sizing machine, sizing mill and reducing mill.
Continuous pipe rolling production The production equipment consists of a piercing mill, a continuous tube rolling mill and a stretch reducing mill. The round billet is pierced into a capillary and inserted into a mandrel. The rolling mill is continuously rolled through a two-high rolling mill in which the axes of 7-9 rollers are mutually arranged at 90 °. The mandrel drawn after rolling is reheated for tension reducing. It can be rolled to 165m steel pipe. The annual output of 140mm continuous pipe rolling mill is 40 ~ 600 thousand tons, which is 2 ~ 4 times of that of automatic tube rolling mill. This unit is characterized by suitable for the production of steel pipe diameter 168 mm below, equipment investment, large installed capacity, mandrel up to 30m, complex processing and manufacturing. The MPM (Continuous Pipe Rolling Machine) with Restricted Mandrel appeared in the late 1970s. During rolling, the external force forces the mandril to move at a speed less than that of the steel tube. The metal flow condition can be improved.
(C) Polygonal and circular ingots or continuous casting billets are used as raw materials in the production of periodic tube rolling, After heating, it is perforated into cup-shaped blank by water pressure, and then it is rolled into a capillary by a two-high cross rolling extender. Then, a section of steel pipe is produced by rolling through the roller on a periodic pipe rolling mill with holes and grooves of varying diameter. The pipe rolling mill is also called Pilger mill. Steel ingots are used as raw material in the production of periodic tube rolling, which is suitable for rolling large diameter thick wall tubes and variable section tubes.
Three high rolling pipe production is mainly used to produce thick wall pipe with high dimensional precision. The wall thickness precision of the pipe produced by this method is ± 5%, which is about one time higher than that produced by other methods. The process flow is shown in Figure 4. The invention of the new three-high skew rolling mill (called Transval rolling mill) in the 1960s led to the rapid development of this method. The new rolling mill is characterized by rapidly turning the inlet rotating frame to change the rolling angle when the rolling reaches the tail. The ratio of the outer diameter to the wall thickness of the production variety is expanded from 12 to 35. Not only can the thin-wall tubes be produced, but also the productivity is increased.
The traditional method of pipe jacking is to extend the billet into cup-shaped capillary by hydraulic perforation and skew rolling. The long mandrel is inserted into the bottom of the capillary cup by a push rod, and the pipe is formed by top rolling through a series of gradually decreasing holes and grooves. This method has less investment in equipment and can be used to produce extra large and extra thick pipes with diameters up to 1070mm and wall thickness to 200mm. But the production efficiency is low, the wall thickness is relatively thick and the pipe length is short. After the appearance of CPE process, the tube blank is pierced by skew rolling and extended by top rolling after closing. It overcomes some shortcomings of traditional method and has become a better method in seamless pipe production.
(6) The peeled round blank is first perforated or expanded in extrusion pipe production, After induction heating or salt bath heating, and the inner surface coated with lubricant into the extruder, metal through the die hole and mandrel annular gap is extruded into pipe (Figure 5). Mainly used for the production of low plastic superalloy pipe, special-shaped pipe and composite pipe, non-ferrous metal pipe and so on. This method produces a wide range but low yields. In recent years, due to the improvement of die materials, lubricants, extrusion speed, extrusion pipe production has also developed.
(7) The pipe rolling process is also called Diessel process. The pierced capillary with a long mandrel is rolled to thin wall tube on a guide plate mill. The mill is similar to the two-high cross piercing mill, but the fixed guide plate is changed into the active guide plate. Because of the long mandrel, the inner wall of the pipe is smooth and has no scratch. But tools are expensive and complex to adjust. Mainly used for the production of carbon steel pipe with external diameter of 150mm or less. At present, the use of less, there is no great prospects for development.
Spinning tube production Flat or hollow blank in a spinning machine through one or more spinning processing into thin-walled tube. The pipe has high precision, good mechanical properties, wide size range, but low production efficiency. Mainly used in the production of non-ferrous metal pipe, but also increasingly used in steel pipe production. In addition to the spinning pipe for the production of living appliances, chemical containers and machine parts, mostly used in military industry.
(9) Cold rolling, cold drawing pipe production for the production of small caliber thin wall, precision and special-shaped pipe. The production is characterized by a multi-process cycle process. The elongation can reach 6 ~ 8 (Fig. 6) when the pipe is cold rolled by a cycle mill. The development of high-speed, multi-line, long-stroke and long-billet began in 1960s. In addition, the small roller cold rolling mill has also been developed. It is mainly used for the production of very thin precision tubes with wall thickness less than 1mm. The cold rolling equipment is complicated, the tool processing is difficult and the variety and specification change is not flexible. Usually the combined process of cold rolling and cold drawing is adopted, that is, first cold rolling to reduce the wall to obtain large deformation, then cold drawing to obtain a variety of specifications.

Equipment for the production of seamless steel pipe
Punch
Round tube blanks are rolled into hollow thick-walled tubes (linings), with an angle of inclination to the rolling line formed by the axis of the two rollers. In recent years, the angle of inclination has been increased from 6 ° -12 ° to 13 ° -17 °, making the speed of perforation faster. In order to reduce the wall thickness of the capillary pipe, secondary perforation is used to produce the pipe with diameter over 250mm. Some new technologies, such as perforation with active rotating guide plate, perforation with back thrust, axial discharge and cyclic top welding, have also been developed, which strengthen the perforation process and improve the quality of capillary.
Automatic pipe rolling machine
The thick – walled capillary is rolled into thin – walled hollow. The total elongation is about 1.8 ~ 2.2 after 2 ~ 3 pass rolling to the wall thickness of finished product. Since 1970s, the production efficiency has been improved and the pipe rolling mechanization has been realized by the techniques of single slot roller, double stand tandem rolling, double slot tracing rolling and spherical head.
Uniform machine
The structure is similar to the piercer. The purpose of leveling is to eliminate defects in the internal and external surface area and eliminate the ovality of the pipe, and to reduce the uneven horizontal wall thickness. In recent years, the use of three-roller leveling machine has improved the deformation and leveling efficiency of the whole machine.
Sizing machine
The reducing mill is composed of 3-12 racks, and the reducing rate is 3-28%. The tension reducing mill, which appeared in the 1950s, controls the wall thickness by proper tension while adjusting the roller speed and reducing diameter. The new type tension reducing mill generally uses three rollers, has 18 ~ 28 frames, the maximum diameter reduction rate is 80%, the wall reduction ratio is 44%, and the outlet speed is 18 mm per second. Tension reducing mill has the disadvantage of thickening at both ends, which can be eliminated by “sudden electrical control at the end of the head and the tail” or by slight tension reducing.
Automatic pipe rolling mill
Commonly used series of external diameter of 100mm, 140mm, 250mm and 400mm four kinds, production diameter of 17 ~ 426mm steel pipe. The features of the unit are that the main deformation is realized on the piercer, the specification is flexible and the production variety is wide. Due to the development of continuous pipe rolling technology, the units below 140mm are no longer built.

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Seamless steel pipe according to the use of different, there are thick seamless pipe and thin-walled seamless pipe. Seamless steel pipe is widely used.
1, the general purpose seamless steel pipe according to the material, by ordinary carbon structural steel, low alloy structural steel or alloy steel rolling. For example, No. 10, No. 20 and other low carbon steel seamless pipe, mainly used for steam, gas, liquefied gas, natural gas, various petroleum products and a variety of other gases or liquids pipeline; 45, 40Cr and other carbon steel manufacturing seamless pipe, mainly used to manufacture various machine parts and pipe fittings.
2, general purpose seamless steel pipe is also divided by chemical composition and mechanical properties of supply, according to the water pressure test supply. Seamless steel pipes subjected to fluid pressure shall be guaranteed to pass the hydrostatic test.
3, special purpose seamless tube for boiler, geological exploration, bearing, acid and so on. Such as petroleum geological drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation with high-precision structural steel pipe.
Structural seamless steel pipe, mainly for general structure and mechanical structure. Its representative material (brand): carbon steel 20, 45 steel; Alloy steels Q345, 20Cr, 40 Cr, 20CrMo, 30-35CrMO, 42CrMe, etc.
Seamless steel pipe for conveying fluid is mainly used in engineering and large equipment for conveying liquid pipeline. Representative material (grade) for 20, Q345, etc.
Low and medium pressure boiler seamless steel pipe, mainly used for industrial boiler and life boiler low and middle pressure fluid pipeline. It is made of steel 10 and 20.
High-pressure boiler seamless steel pipe, mainly used in power stations and nuclear power plants boiler high temperature, high pressure fluid delivery box and pipeline. Typical materials are 20G, 12Cr1MoVG, 15CrMoG, etc.
Marine carbon steel and carbon manganese steel seamless pipe, mainly used for marine boiler and superheater I, II grade pressure pipe. Representative material for 360, 410, 460 steel grade.
High-pressure fertilizer equipment seamless steel pipe, mainly used in fertilizer equipment high temperature and high pressure fluid pipeline. Representative materials for 20, 16 Mn, 12CrMo, 12CR2Mo and so on.
Seamless steel pipe for petroleum cracking is mainly used for boiler, heat exchanger and fluid pipeline in petroleum smeltery. The representative materials are 20, 12CrMo, 1Cr5Mo and 1Cr19Ni11Nb, etc.
Seamless steel pipe for gas cylinder, mainly used for making various gas and hydraulic gas cylinder. Its representative materials are 37Mn, 34Mn2V, 35CrMo and so on.
The hot-rolled seamless steel pipe for hydraulic prop is mainly used for making coal mine hydraulic support, cylinder, column and other hydraulic cylinder and column. Its representative materials are 20, 45, 27SiMn and so on.
High-pressure seamless steel pipe for diesel engine, mainly used for high-pressure oil pipe of diesel injection system. Its steel pipe is generally cold drawn pipe, its representative material is 20A.
Cold-drawn or cold-rolled precision seamless steel pipe, mainly used for mechanical structure, carbon pressure equipment, requiring high dimensional accuracy, good surface finish of steel pipe. Its representative material 20, 45 steel and so on.
Cold drawn seamless steel pipe special-shaped steel pipe, mainly used for the production of various structural parts and components, its material for high-quality carbon structural steel and low alloy structural steel.
The precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinder is mainly used to make the precision inside diameter of the cold drawn or cold rolled seamless steel tube for hydraulic or pneumatic cylinder. Its representative material is 20, 45 steel and so on.
Stainless steel seamless steel tubes for boiler and heat exchanger are mainly used in boiler, superheater, heat exchanger, condenser and catalytic tube of chemical enterprise. Used for high temperature, high pressure, corrosion resistant steel pipe. Its representative materials are 0Cr18Ni9, 1Cr18Ni-9Ti, 0Cr18 Ni12Mo2Ti and so on.
Stainless steel seamless steel pipe for structure. Mainly used for general structure (hotel, restaurant decoration) and chemical enterprise mechanical structure with atmospheric, acid corrosion and a certain strength of steel pipe. Its representative materials are 0-3Cr13, 0Cr18Ni9, 1Cr18NI9Ti, 0cr18Ni12Mo2Ti and so on.
Fluid transport with stainless steel seamless pipe, mainly for the transport of corrosive media pipeline. The representative materials are 0Cr13, 0Cr18Ni9, 1Cr18 Ni9Ti, 0cr17 Ni12Mo2 and 0Cr18 Ni 12Mo2Ti.
The seamless steel pipe for automobile axle shaft sleeve is mainly used to make the high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel tube for the automobile axle sleeve and the drive axle shell shaft tube. Its representative materials are 45, 45Mn2, 40Cr, 20CrNi3A, etc.
What is the difference between seamless pipe and seamless pipe?
From the process, seamless pipe is a rolling molding, with round steel heating, perforation, hot rolling, sizing, straightening out the production.
Seamless steel pipe is also called welded steel pipe referred to as welded pipe, steel plate or steel belt bending deformation to welding, there are straight welded pipe and spiral welded pipe can be clearly seen welded reinforcement, seamless steel tube is not.
Some of the seamless steel pipe has to do without welding reinforcement, careful observation can be seen traces.
Seamless steel pipe pressure in about 10, higher. Slotted pipe can be used for low pressure fluid, seamless pipe for high pressure (different materials according to specifications).
Seamless steel pipe is mainly used in construction; Seamless steel pipe is mainly used for machining, fluid transport. Seamless steel pipe in all aspects of the basic application are stronger than the slotted steel pipe. Seamless steel pipe prices than the high seam pipe.

Seamless steel pipe is made of the whole round steel perforated, there is no weld on the surface of steel pipe, called seamless pipe. According to the production method, seamless steel pipe can be divided into hot-rolled seamless steel pipes, cold-rolled seamless pipes, cold drawn seamless pipe, seamless pipe extrusion, pipe jacking. According to the section shape, seamless steel pipe is divided into round and shaped two kinds, shaped pipe has square, oval, triangle, hexagonal, melon seed shape, star, with a variety of complex shapes. The maximum diameter is 900mm, the minimum diameter is 4mm. According to the use of different, there are thick seamless steel pipe and thin seamless pipe. Seamless steel pipe is mainly used for petroleum geological drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation with high-precision structural steel pipe.
Classification of seamless steel pipe:
A steel tube with no seams on the periphery of its cross section. According to the different production methods divided into hot-rolled pipe, cold-rolled tube, cold-drawn pipe, extrusion pipe, pipe jacking, etc., have their own process.
Materials include normal and quality carbon structural steel (Q215-A ~ Q275-A and 10-50 steel), low alloy steel (09MnV, 16Mn etc.), alloy steel, stainless acid-resistant steel and so on.
According to the use divided into general use (for water, gas pipelines and structural components, mechanical parts) and special (for boilers, geological exploration, bearings, acid, etc.) two categories.
Seamless steel pipe uses:
1, the general use of seamless steel pipe from ordinary carbon structural steel, low alloy structural steel or alloy steel rolling, the largest production, mainly used for the transmission of fluid pipeline or structural parts.
2, divided into three categories according to different uses:
A, according to chemical composition and mechanical properties;
B, according to the mechanical properties of supply;
C, according to water pressure test supply. Pipes supplied according to class a and b shall also be subjected to hydrostatic testing if used to withstand liquid pressures.
3, special purpose seamless pipe has boiler seamless pipe, chemical power, geological seamless pipe and petroleum seamless pipe.
Seamless steel pipe with hollow section, a large number of fluids used for the transmission of pipelines, such as oil, natural gas, gas, water and some solid materials pipeline. Compared with solid steel such as round steel, the steel tube is a kind of economic section steel because its bending and torsion strength is the same.
Widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in building construction, etc. The utility model can improve the material utilization ratio, simplify the manufacturing process, save material and processing time, and has been widely used in steel pipe manufacturing.
Seamless steel pipe production process:
Main production process of hot-rolled seamless steel pipe (△ main inspection process):
Tube blank preparation and inspection → tube blank heating → perforation → tube rolling → tube reheating → sizing → heat treatment → straightening → finishing → inspection → (nondestructive, physical and chemical examination) → storage
Cold rolled (drawn) seamless steel pipe main production processes:
Blank preparation → pickling lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection
The general seamless steel pipe production process can be divided into two kinds of cold drawing and hot rolling, cold rolling seamless pipe production flow is generally more complicated than hot rolling. Tube billet first three rollers rolling, after extrusion to determine the diameter test, if the surface does not respond to cracks after the tube to cut through the cutting machine, cutting growth of about one meter of billet. Then enter the annealing process, annealing to use acidic liquid pickling, pickling should pay attention to whether there is a large number of surface foaming, if there are a lot of foaming produced that the quality of steel pipe can not reach the corresponding standard. The appearance of cold-rolled seamless steel pipe is shorter than hot-rolled seamless pipe, cold-rolled welded seamless pipe wall thickness is generally smaller than hot-rolling seamless steel tube, but the surface looks brighter than thick-walled seamless steel tubes, the surface does not have too much rough, caliber is not too much burr.
Hot rolled seamless steel pipe delivery state is generally hot rolled state after heat treatment for delivery. Hot rolled seamless steel pipe after quality inspection to go through the staff of strict manual selection, After the quality inspection to the surface oiling, and then followed by several cold drawing experiments, hot rolling treatment to perforated experiments, if the perforated expanding is too large to be straightened. After straightening, the transmission device is sent to the flaw detector for flaw detection experiment, and finally the label is affixed, the specification is arranged and placed into the warehouse.
Round tube blank → heating → perforation → three-high cross rolling, continuous rolling or extrusion → tube removal → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → storage seamless steel pipe is made of ingot or solid tube blank through perforation into capillary, Then made by hot rolling, cold rolling or cold dial. Seamless steel pipe specifications with the outside diameter * wall thickness mm number.
The outside diameter of hot-rolled seamless pipe is generally greater than 32 mm, the wall thickness is 2.5-200 mm, The outer diameter of cold-rolled seamless steel tube can be 6mm, the wall thickness can be 0.25mm, and the outside diameter of thin-walled pipe can be 5mm. The thickness is less than 0.25mm. The size precision of cold rolling is higher than that of hot rolling.
General seamless steel pipe is 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low alloy steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled. 10, 20 and other low carbon steel seamless pipe is mainly used for fluid delivery pipeline. 45, 40Cr and other carbon steel made of seamless pipe used to manufacture mechanical parts, such as cars, tractors of the force parts. General seamless steel pipe to ensure the strength and flattening test. Delivery of hot-rolled steel pipes in hot-rolled or heat-treated condition; Cold rolling is delivered in heat treated condition.
Hot rolling, as the name implies, the temperature of the workpiece is high, so the deformation resistance is small, and large deformation can be achieved. Take the rolling of steel plate as an example, the thickness of continuous casting slab is about 230 mm, and the final thickness is 1 ~ 20 mm after rough rolling and finishing rolling. At the same time, because of the small width-to-thickness ratio of the steel plate, the size precision requirement is relatively low, and the shape problem is not easy to appear. For organizational requirements, generally through controlled rolling controlled cooling to achieve, That is to control the starting and finishing temperature of finishing rolling. Round tube blank → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydrostatic test (flaw detection) → marking → storage.

Stainless steel pipe fittings belong to a kind of pipe fittings, it is made of stainless steel so called stainless steel pipes. Stainless steel pipe fittings include: stainless steel elbow, stainless steel tee, stainless stainless steel four, the size of the head, and so on.
Reducing pipe necking, is to heat one end of the stainless steel large diameter pipe to the red hot state, With a hammer, make its diameter reduced, become a big one small pipe, commonly known as “size head,” or “change diameter.” Sometimes the diameter difference between the two ends of the stainless steel head is too large, the large diameter of the pipe at one end of the first cut off a few curved triangular pieces, Then reheat to red-hot state, with a hammer, so that its cut off the gap and then close together to form a joint, and the formation of the small port full circle, the seam welding. According to the size of reducing diameter pipe, it can be divided into one pressing forming or multiple pressing forming. In addition to using steel pipe as raw material to produce size head, some size head can also be produced by stamping process of steel plate. The shape of the drawing die is designed according to the inner surface of the head. The blanking steel plate is stamping and drawing with the die.
In addition to using steel pipe as raw material to produce size head, some size head can also be produced by stamping process of steel plate. Size head (reducer) is used for pipe diameter of a pipe fitting. The forming process of the stainless steel head is usually reduced diameter, expanded diameter or reduced diameter plus expanded diameter. The reducers of some specifications can also be stamped. In the process of reducing / expanding forming the size head, the tube blank with the same diameter at the big end of the diameter head is put into the forming die, and the metal is moved along the die cavity and contracted by pressing along the axial direction of the tube.
Benefits of stainless steel pipe
1, long service life
Stainless steel tubing has the longest service life. From the domestic and foreign stainless steel pipe application status analysis, stainless steel water pipe application life of 100 years, at least there will be 70 years, with the building life as long.
2, strong corrosion resistance
One of the most prominent advantages of stainless steel tubes is their excellent corrosion resistance, because stainless steel can passivate with oxidizers, so it is slightly better than a variety of tubes.
3, good heat resistance and insulation properties
The thermal conductivity of stainless steel pipe is 1 / 25 of copper pipe and 1 / 4 of general steel pipe, which is very suitable for hot water transportation. The most commonly used stainless steels in the hydraulic industry are 316 and 304 stainless steels, which can meet most water treatment and transportation conditions.
4, high compressive strength
304 stainless steel pipe tensile strength is 2 times of steel pipe, plastic pipe 8 to 10 times. The compressive strength of the material determines whether the water pipe is strong and crash-resistant, safe and stable. Safety and stability is the most important standard in building water supply. The probability of leakage of stainless steel pipes is very small under the condition of external force or external factor impact.
304 is a universal stainless steel pipe, it is widely used in the production of good comprehensive performance (corrosion resistance and formability) of equipment and parts. 304 stainless steel pipe is in accordance with the United States ASTM standard produced a stainless steel brand, equivalent to our 0Cr19Ni9 (0Cr18Ni9) stainless steel. 304 chromium 19%, 9% nickel, is the most widely used stainless steel, heat-resistant steel. For food production equipment, general chemical equipment, nuclear energy and so on.
The use of stainless steel pipes and the environment in which they are used should be considered before selecting stainless steel pipe fittings. Such as: decoration generally use welded pipe, fluid transmission generally use seamless pipe, Medical or kitchen to use sanitary stainless steel pipe, pressure use thick wall pipe, generally indoor use 200 series material can, outdoor use 304 material, and in acid and alkali places or coastal areas generally use 316 above material.
In the selection of steel pipe to determine the material standards. To 304 material as an example: a, from the price analysis, if 304 material stainless steel pipe material even lower than the common price of 201 material on the market, to carefully identify, may be other material posing; B, identify whether the tube surface stamped material “304” words, and to obtain factory quality certificate as evidence; C, available acidic reagent test, 30 seconds later material 304 does not change color, 201 black; D, bulk purchase can take samples sent to the national authoritative testing center for component analysis.
Watch the color of the outer surface and inner wall of the tube is bright and smooth, whether the thickness is uniform or rough. General welded pipe this basic need not check, and seamless steel pipe is cold drawn or hot rolled production, Improper operation in the production process easy to produce uneven thickness, pipe surface cracks and other phenomena, and the surface roughness is generally seamless pipe not polished, if the appearance of no special requirements do not affect the use.
Should choose to buy by the quality and technical supervision bureau assessment to excellent products. Having a long use of testimonials and good word of mouth among customers is a direct and effective way to buy.
Rolling pipe often appear within the heavy skin, pitting, and rolling green line, in general these can not be avoided, also basically does not affect the use, but must choose as little as possible in the purchase, especially to check the inner surface.

Introduction of steel pipe
Steel pipe is a very important building materials in life, with its unique product features and beautiful and favored. Steel pipe is a kind of economic steel, steel products and varieties of specifications is extremely wide, its performance requirements are various. Steel tubes can be used to transport fluids and powdery solids, exchange heat energy, manufacture machine parts and containers. It can reduce weight, save metal by 20 ~ 40% and realize factory mechanization construction by using steel pipe to make construction frame, strut and machine support. Using steel pipe to make highway bridge not only can save steel, simplify construction, but also can greatly reduce the area coated with protective layer, saving investment and maintenance costs.
Types and Uses of Steel Pipes
By production method
Seamless steel pipe can be divided into seamless pipe and seamless pipe, seamless pipe referred to as straight seam pipe. Seamless steel pipe can be used in a variety of industries, such as liquid pressure pipeline and gas pipeline. Welded pipes can be used for water pipes, gas pipes, heating pipes, electrical pipes and so on.
Types of steel pipe
1, pipe pipe. Such as: water, gas pipes, steam pipes with seamless pipe, oil pipeline, oil and gas trunk pipe. Agricultural irrigation faucets with pipes and sprinkler irrigation pipes.
2, thermal equipment pipe. Such as the general boiler boiling water pipe, superheated steam pipe, locomotive boiler superheated pipe, smoke pipe, small pipe, arch brick pipe and high temperature and high pressure boiler pipe.
3, machinery industry pipe. Such as aeronautical structural tubes (circular tubes, oval tubes, flat oval tubes), Automobile axle shaft tube, axle tube, automobile tractor structure tube, tractor oil cooler tube, agricultural machinery with square and rectangular tube, transformer tube and bearing tube.
Pipes for petroleum geological drilling. Such as: oil drilling pipe, oil drill pipe (kelly and hexagonal drill pipe), drilling, oil tubing, oil casing and various pipe joints, geological drilling pipe (core pipe, casing, active drill pipe, drill, by hoop and pin joints, etc.).
5, chemical industry pipe. Such as: petroleum cracking pipe, chemical equipment heat exchanger and pipeline pipe, stainless acid-resistant pipe, fertilizer with high-pressure pipe and transport chemical medium pipe.
6, other departments with pipe. Such as: container pipe (high-pressure gas cylinder pipe and general container pipe), instrument pipe, watch case pipe, syringe needle and medical equipment pipe.
Steel pipe material
Steel pipe material (that is, steel) can be divided into: carbon pipe and alloy pipe, stainless steel pipe and so on. Carbon pipe can be divided into ordinary carbon steel pipe and quality carbon structural pipe. Alloy pipe can be divided into: low alloy pipe, alloy structure pipe, high alloy pipe and high strength pipe. Bearing tube, heat and acid resistant stainless tube, precision alloy (such as kovar alloy) tube and high temperature alloy tube.
Steel pipe specification size
Divide an inch into eight equal parts: 1 / 8, 1 / 4, 3 / 8 and 1 / 2. 5 / 8. 3 / 4 and 7 / 8.
Equivalent to the usual said 1 to 7 branches, smaller sizes with 1 / 16, 1 / 32, and 1 / 64 to express the unit or inch. If the denominator and the numerator can be reduced (e.g. the numerators are 2, 4, 8, 16, 32) it should be reduced.
Inch is in the upper right corner hit two prime, such as 1 / 2, “such as DN25 (25mm, the same below) water pipe is British 1″ water pipe, but also before the liberation of 8 points water pipe. The DN 15 hose is 1 / 2 inch. ” The water pipe is also a four-minute water pipe before liberation. For example, the DN20 pipe is 3 / 4 inch ” The water pipe is also a six-minute water pipe before liberation. 一、尺寸:DN15、DN20、DN25、DN32、DN40、DN50、DN65、DN80、DN100、DN125、DN150、DN200、DN250.
Steel pipe selection
1, the choice of color is generally uniform, smooth and smooth inner and outer walls, no bubbles, depressions, impurities and other defects affecting surface performance.
2, to see the product logo is not complete, steel pipe should have a factory name or trademark; Production date, product name, specifications, size, implementation standard number, etc., steel pipe to have the name of the product, nominal outside diameter, pipe series S, etc., the handwriting should be clear, and check whether the identification is consistent with the actual.
3, should buy the same brand of pipe and pipe fittings, because different brands of raw materials may not be the same for pipe fittings welding will have adverse factors, long-term use will cause welding leakage.
4, a good steel pipe strength is not broken, so can not be broken by whether to judge the quality of steel pipe. Due to the impact resistance of steel pipe is better than the real steel pipe, so the steel pipe more easily smashed, smashed broken is often steel pipe.
Steel pipe maintenance
1, clean water cleaning
Water cleaning is to use water to wash the inner wall of the steel pipe, but for those attached to the wall of steel pipe calcium magnesium ion scale, biological clay and other impurities are not completely removed, the effect is not obvious.
2, potion cleaning
Potion cleaning is to add chemical reagents in the water, but the chemical composition of the steel pipe is corrosive, but also shortens the life of steel pipe, is a kind of Gang Ze fishing practice, not desirable.
3, physical cleaning
Now on the market, the working principle of this cleaning is basically compressed air as a power, The use of a launcher to launch a special projectile larger than the inner diameter of the pipeline into the pipe, so that it along the pipeline wall high-speed movement and full friction, to achieve the effect of cleaning the inner wall of the pipe. This way cleaning effect is obvious, basically no harm to the pipeline, is the most thorough cleaning method so far.