Seamless steel pipe is made from ingots or solid billets that are perforated to form a burr tube, and then hot rolled, cold rolled or cold dialed. 45 seamless steel pipe is one of the materials of steel and is a high quality carbon structural steel, which is used by a large number of mold production companies to make mold steel. Seamless steel pipe is made of high quality carbon steel or alloy steel and is available in hot rolled and cold rolled (drawn). Welded steel pipe is rolled into a tube-shaped steel plate to butt or spiral seam welding, in the manufacturing method, and is divided into low-pressure fluid transmission with welded steel pipe, spiral seam electric welding steel pipe, direct coil welding steel pipe, electric welding pipe, etc.. Seamless steel pipe can be used for various liquid and gas pipelines, etc. Welded pipes can be used for water pipelines, gas pipelines, heating pipelines, etc. From the caliber, <φ76, accounting for 35%, <φ159-650, accounting for 25%. In terms of varieties, 1.9 million tons of general purpose pipes, accounting for 54%; 760,000 tons of petroleum pipes, accounting for 5.7%; 150,000 tons of hydraulic pillar and precision pipes, accounting for 4.3%; 50,000 tons of stainless steel pipes, bearing pipes and automobile pipes, accounting for 1.4%.

The raw material for rolling seamless steel pipe is a round pipe billet. The round pipe embryo is cut and processed into a billet of about 1 meter in length by a cutting machine and sent to the furnace for heating by a conveyor belt. The billet is sent to the furnace to be heated at a temperature of about 1200°C. The fuel is hydrogen or acetylene. Temperature control in the furnace is a key issue. After the round billet is discharged from the furnace, it is hollowed out by a pressure piercing machine. The more common perforating machine is the conical roller perforating machine, which has high productivity, good product quality, large perforation and expansion capacity, and can perforate a variety of steel grades. After perforation, the round pipe billet has been three rolls of oblique rolling, continuous rolling or extrusion. After extrusion, the tube should be sized. Sizing machine through the conical drill bit high-speed rotation into the steel embryo perforation, the formation of steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the sizing machine bit. After sizing, the steel pipe enters the cooling tower and is cooled by water spray, and after cooling, the steel pipe is straightened. Steel pipe is straightened and sent by conveyor belt to the metal flaw detector (or hydraulic test) for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. The steel pipe quality inspection is followed by a strict hand selection. After quality inspection, the steel pipe is sprayed with paint with number, specification, production lot number, etc. and lifted into the warehouse by crane.

Specification: The specification of seamless steel pipe is expressed by the number of millimeters of outer diameter * wall thickness. φ:756MM; wall thickness: 100MM or less

Classification of seamless steel pipe: Seamless steel pipe is divided into two categories: hot rolled and cold rolled (dialed) seamless steel pipe.

Seamless steel pipe execution standards

Structural steel pipe GB/T8162-99 Oil drilling steel pipe YB528-65 Fluid steel pipe GB/T8163-99

Marine steel pipe GB5312-85 medium-pressure boiler steel pipe GB/T3087-99 petroleum jacket steel pipe API5CT

Geological drilling steel pipe YB235-70 Automotive semi-axial steel pipe GB3088-8 Chemical fertilizer steel pipe GB6479-86

Hydraulic pillar steel pipe GB173-98 Petroleum cracking steel pipe GB9948-88 Pipeline steel ASTMA53B/106B/API 5L B High-pressure boiler steel pipe DIN17175 ST45.8-Ⅲ GB5310-95 20G

Seamless steel pipe is rolled from solid billets after perforation.

Hot-rolled seamless steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes, etc.

Cold rolled (dialed) seamless steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, other steel pipe, but also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless thin-walled steel pipe, shaped steel pipe. Hot-rolled seamless steel pipe outer diameter is generally greater than 32mm, wall thickness 2.5-75mm, cold-rolled seamless steel pipe diameter can be up to 6mm, wall thickness can be up to 0.25mm, thin-walled tube outer diameter can be up to 5mm, wall thickness is less than 0.25mm, cold-rolled than hot-rolled high dimensional accuracy.

Seamless steel pipe for general use: It is made of 10, 20, 30, 35, 45 and other high quality carbon knotted steel 16Mn, 5MnV and other low alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled. 10, 20 and other low carbon steel made of seamless steel pipe is mainly used for fluid transportation pipeline. 45, 40Cr and other medium carbon steel made of seamless steel pipe Used to manufacture mechanical parts, such as cars, tractors of stressed parts. Seamless steel tubes are generally used to ensure strength and crush test. Hot-rolled steel pipe is delivered in hot-rolled condition or heat-treated condition; cold-rolled is delivered in heat-treated condition.

Seamless steel tubes for low and medium pressure boilers: used for manufacturing various low and medium pressure boilers, superheated steam tubes, boiling water tubes, water-cooled wall tubes and superheated steam tubes for locomotive boilers, large smoke tubes, small smoke tubes and arch brick tubes, etc. Hot-rolled or cold-rolled (dialed) seamless steel tubes made of high-quality carbon structural steel. Mainly made of 10, 20 gauge steel, in addition to ensuring the chemical composition and mechanical properties to do the hydraulic test, rolled edge, flaring, flattening and other tests. Hot-rolled to hot-rolled state delivery, cold-rolled (dial) to heat treatment state delivery.

High-pressure boiler steel pipe: mainly used to manufacture high-pressure and above-pressure steam boiler pipes with high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipe, these boiler tubes are often in high temperature and high pressure work, the tube in the role of high-temperature flue gas and water vapor will also be oxidation and corrosion, so the steel pipe is required to have a high lasting strength, high oxidation resistance, and has good organizational Stability, the use of steel grades are: high-quality carbon structural steel grades 20G, 20MnG, 25MnG; alloy structural steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.; rust heat-resistant steel commonly used 1Cr18Ni9, 1Cr18Ni11Nb 1Cr18Ni11Nb high-pressure boiler tube in addition to ensure the chemical composition and mechanical properties, to do the hydraulic test one by one, to make the flaring, flattening test. Steel tube to heat treatment state delivery. In addition, the finished steel pipe microstructure, grain size, decarburization layer also have certain requirements.

Seamless steel pipe for geological drilling and petroleum drilling: To find out the underground rock structure, groundwater, oil, natural gas and mineral resources, drilling rigs are used to drill wells. Oil and natural gas extraction is even more inseparable from drilling, and seamless steel pipes for geological drilling and oil drilling are the main equipment for drilling, mainly including core outer pipe, core inner pipe, casing, drill pipe, etc. As the pipe for drilling has to work deep into the stratigraphic depth of several thousand meters, the working conditions are extremely complicated, and the drill pipe is subjected to stresses such as tension, pressure, bending, torsion and unbalanced impact load, as well as mud and rock abrasion, so the pipe must have sufficient strength, hardness, wear resistance and impact toughness. (geological Hanyu Pinyin prefix) plus the number one represents the steel yield point, commonly used steel number DZ45 45MnB, 50Mn; DZ50 40Mn2, 40Mn2Si; DZ55 40Mn2Mo, 40MnVB; DZ60 40MnMoB, DZ65 27MnMoVB. steel tubes are delivered in heat-treated condition.

Petroleum cracking pipe: Seamless steel pipe for furnace pipe, heat exchanger pipe and pipeline in petroleum refineries. Commonly used high-quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat-resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti) manufacturing. In addition to the chemical composition and various mechanical properties of the steel pipe, but also to ensure the hydraulic pressure, flattening, flaring and other tests, and surface quality and non-destructive testing. Steel tubes are delivered in heat-treated condition. Stainless steel pipe: with a variety of stainless steel hot-rolled, cold-rolled stainless steel pipe, widely used in petroleum, chemical equipment pipelines and various uses of stainless steel structural parts, in addition to the chemical composition and mechanical properties should be guaranteed, where used to withstand fluid pressure of the steel pipe to ensure that the hydraulic test qualified. A variety of special steel pipe to ensure the conditions as specified.

It is true that galvanized steel pipes are actually ordinary welded steel pipes that have been galvanized. However, due to the different production processes, galvanized steel pipes are also differentiated by type.

For example, the order of galvanizing and processing is different, giving rise to two different products, and the price of galvanized steel pipe may also be different.

Galvanized steel pipe

Galvanized steel strip is produced by first galvanizing steel raw materials and then post-processed to produce a steel pipe called galvanized strip steel pipe, also called pre-galvanized steel pipe.

The raw steel material is first produced into a common steel pipe with the required welded steel pipe specifications, and then galvanized. The galvanized steel pipe produced in this way is called hot-dip galvanized steel pipe, also known as hot-dipped galvanized steel pipe.

There is a big difference in the price of these two types of galvanized steel pipes, with galvanized strip steel pipes being much cheaper than hot-dip galvanized steel pipes. This is due to the fact that in terms of zinc layer thickness, the steel pipe produced by the hot-dip galvanizing process will be thicker and have a stronger corrosion resistance.

However, many customers still tend to buy pre-galvanized steel pipes when they ask for quotations to buy galvanized square pipes. Not only because of the cheap price, but also because on the basis of the price, there is not much difference between the use and the hot-dip galvanized steel pipe.

However, it is important to note that if you need a steel pipe with a relatively high wall thickness, such as requiring a wall thickness of 2.5mm or more. Then the steel pipe manufacturer will default to your request for a hot dipped galvanized steel pipe. This is because the raw material for pre-galvanized steel pipes, galvanized strip steel, cannot meet such wall thickness conditions.

In other words, under the same conditions of use, people will use the cheaper pre-galvanized steel pipe and choose the hot-dipped galvanized steel pipe in special cases. The characteristics of these two types of galvanized steel pipes must be distinguished.

3.5 galvanized pipe,galvanized steel pipe factory,

We are currently the second largest consumer of electricity in the world, with the installed capacity of electricity increasing from 520 million kilowatts in 2005 to 1,144 million kilowatts in 2012, with an average annual growth rate of 11.97%. As a country with more coal and less gas and oil, coal-fired power generation still dominates our total power generation capacity. According to BP’s World Energy Statistics Yearbook 2012, coal accounts for 70.39% of the primary energy consumption structure.

Currently, the installed thermal power generation capacity accounts for 71.59% of the total installed power generation capacity, and the installed thermal power generation capacity increased from 390 million kilowatts in 2005 to 819 million kilowatts in 2012, with an average annual growth rate of 11.18%.

Thermal power generation is a form of power generation that uses the thermal energy generated by burning coal to heat water, turning it into high-pressure water vapor, which then drives a generator to generate electricity. Thermal power plant mainly consists of three major parts: power generation boiler, steam turbine and generator, in which the steam and water pipes in power generation boiler include reheater pipe, superheater pipe, water cooling wall pipe, coal saver pipe, air preheating pipe, heat conduction pipe, descending pipe and various joint box pipes. Due to the use of the above-mentioned pipeline in high temperature and high pressure conditions for a long time, the pipeline will be oxidation and corrosion under the action of high-temperature flue gas and water vapor, so the requirements of steel pipe with high lasting strength, high oxidation resistance corrosion performance and good organizational stability. To meet the above requirements, stainless steel tubes are used in large numbers in thermal power boilers. China’s thermal power unit investment has driven the development of stainless steel tubes for the power equipment manufacturing industry.

At present, with the development of the chemical industry, the application of duplex stainless steel is becoming more and more widespread, and the domestic duplex stainless steel pipe is growing at a rate of 10% per year, and has a great future in the petroleum, urea and other industries.

The outstanding performance of duplex stainless steel pipe is high yield strength and stress corrosion resistance, with good weldability, welding cold cracking and hot cracking sensitivity are less. In Japan, austenitic and ferritic stainless steel welded pipe in the petrochemical industry in the pipeline system accounted for 54% of the market share.  Stainless steel welded pipe is mainly used in the decorative field, the use of corrosion-resistant welded pipe in the petrochemical field is still basically blank.

Stainless steel national standards have not been revised for more than a decade, in the revision of the national standard must be considered duplex stainless steel standard and revision. Foreign for 80% of the production of 2205 grade specifically developed the product factory inspection of the user acceptance criteria, we should also consider the introduction and absorption, enriching the existing inspection methods and standards to promote the production and ordering of duplex stainless steel.

In addition, the duplex stainless steel to develop the potential market for industrial and civil use (such as construction – structures, bridges, concrete reinforcement; such as manufacturing – containers, storage tanks, chemical carriers, speedboats, tankers; and household facilities – high water tanks, electric water heaters, housing water and steam pipes, etc.), and development, trial, promotion of foreign development and suitable for our national conditions (lack of nickel and chromium) of some new varieties (such as low nickel saving duplex stainless steel), I believe that China’s promotion of duplex stainless steel has a very broad application prospects.

Stainless steel is a recognized health material that can be implanted in the human body and is used in almost all areas involving human health. It has been widely used. Stainless steel plumbing is an environmentally friendly material that meets health requirements, can be 100% recycled, saves water, reduces transmission costs, reduces heat loss, avoids sanitary ware pollution and other advantages. The details are shown as follows.

1.Life span
Stainless steel pipe has ^ long service life. Analysis of the use of stainless steel from abroad, the life of stainless steel water pipes can reach 100 years, or at least 70 years, as long as the life of the building.

2. Corrosion resistance
One of the outstanding advantages of stainless steel pipe ^ is its excellent corrosion resistance, which is ^ good in various pipes. Because stainless steel can be passivated with oxidizing agents, forming a layer of tough and dense chromium-rich oxide protective film Dr2O3 on the surface, effectively preventing further oxidation reactions. Other metal pipes, such as galvanized water pipes, copper pipes passivation ability is very small, which is the galvanized copper pipe corrosion resistance is far less than the key reason for stainless steel pipe. Stainless steel does not occur as uniform corrosion of carbon steel, the use of protective coating is not required; the use of stainless steel water pipe, there is no restriction on the chemical composition of the water, because stainless steel in a variety of oxygen content, temperature, PH and hardness of the water have very good corrosion resistance; stainless steel water pipe can withstand very high flow rate, even if the flow rate is greater than 40 m / s, still maintain a very low corrosion rate, not more than 0.003 mm / year Especially suitable for high-rise water supply. Stainless steel generally does not occur in local corrosion, 304 stainless steel can withstand the chloride content of 200ppm, 316 stainless steel can withstand the chloride content of up to 1000ppm, this conclusion is based on exposure test data and has been confirmed by the use of experience. Stainless steel tube thermal expansion coefficient and copper tube is about the same, is 1.5 times the ordinary steel pipe, compared to the stainless steel tube has the characteristics of slow thermal expansion and contraction.

3. Heat resistance and insulation
The thermal conductivity of stainless steel pipe is 1/25 of copper pipe, is 1/4 of ordinary steel pipe, especially suitable for hot water transmission. Water industry ^ often use stainless steel is 316 and 304 stainless steel, they can meet the majority of water treatment and transmission off conditions.

4. Strength
The tensile strength of 304 stainless steel pipe is 2 times that of steel pipe and 8 to 10 times that of plastic pipe. The strength of the material determines whether the water pipe is strong and resistant to impact, safe and reliable. And safety and reliability is the building water ^ important requirements. In the case of impact by external forces, the possibility of leakage of stainless steel water pipes is very small. High building water supply system working pressure is generally greater than 0.6Mpa; the pipe pressure requirements are high. Thin-walled stainless steel pipe due to the excellent mechanical properties, can withstand very high water pressure, up to 10Mpa or more, especially suitable for high-rise water supply.

Many fickle factors indicate the characteristics of corrosive media, namely chemicals and their concentration, atmospheric conditions, temperature, time, so if you do not know the correct nature of the medium, to use the material, the choice of materials is difficult. However, the following can be used as a guide for selection.

Type 304 widely used materials. It can withstand general rust and corrosion in construction, resist food processing media leaching (but corrosion may occur at high temperature states containing concentrated acid and chloride components), and resist organic compounds, dyes, and a wide variety of inorganic compounds.

Type 304L (low carbon), good resistance to nitric acid, and durable medium temperature and concentration of sulfuric acid, widely used as liquid gas storage tanks, used as low temperature equipment (304N), appliances other consumer products, kitchen equipment, hospital equipment, transportation, wastewater treatment devices.

Type 316 contains slightly more nickel than type 304 and contains 2%─3% molybdenum, corrosion resistance is better than type 304, especially in chloride media that tend to cause pitting corrosion. type 316 has been developed for use as sulfite pulpers because it is durable sulfuric acid compounds. Moreover, its use has been expanded to handle many chemicals in the processing industry.

Type 317 contains 3%-4% molybdenum (also the higher level obtained in this series) and contains more chromium than Type 316, providing higher resistance to pitting and crevice corrosion.

Type 430 is lower in alloy than Type 304 and is used for highly polished decorative applications in mild atmospheres, as well as in nitric acid and food processing equipment.

Type 410 has the lower alloy content of the three general-purpose stainless steels and is selected for high strength parts requiring a combination of strength and corrosion resistance, such as strong parts. 410 is resistant to corrosion in mild atmospheres, water vapors, and many mild chemical product media.

Type 2205 is superior to Types 304 and 316 because he has high resistance to chloride stress corrosion cracking and has approximately twice the strength.