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Galvanized steel is steel that has been coated with zinc to prevent corrosion. The steel is submerged in hot, melted zinc, which triggers a chemical reaction that permanently bonds the zinc and steel together. During the galvanization process, the steel is first exposed to zinc at a temperature of approximately 860 degrees. The zinc reacts to available oxygen in the environment to form zinc oxide, which then forms zinc carbonate after reacting to carbon dioxide. Iron molecules in the steel react with the zinc, creating layers of metal that are able to withstand even long term contact with saltwater. Benefits of galvanized steel Because galvanized steel is coated with zinc, it offers many benefits over traditional steel or iron piping. The zinc coating drastically reduces corrosion and prevents minerals from depositing inside the pipe lines. In larger construction projects, such as sewer systems and farm irrigation, galvanized steel pipes are often the piping of choice and often remain in working order with little maintenance for 40 years or more. Galvanized steel is more flame resistant than PVC piping, and is stronger than aluminum piping. This type of metal also works well under freezing conditions. Disadvantages of galvanized steel In spite of its many benefits, there are some advantages of galvanized steel pipe. When mixed with yellow brass, galvanized steel triggers dezincification, and it results in electrolytic action when combined with nonferrous metals, such as copper and brass. Galvanized steel should never be used underground unless properly covered, which can be inconvenient for many jobs, and it often hides significant defects beneath the zinc coating on the steel. Galvanized steel pipes may contain lead, which corrodes quickly and reduces the lifespan of the piping. Moreover, galvanized steel may leave rough patches inside pipes, resulting in serious failures and stoppages that can be expensive to repair. Because of these issues, most modern homes use copper piping as an alternative. There are several such common defects and disadvantages of galvanized steel pipe: 1. gray zinc coating is the result of a mixture of iron and zinc alloy which caused; 2. galvanized steel surface to form a thick edge, which means that the edges of the zinc layer thicker than the middle part, it becomes a thick edge defects and not conducive to strip coiling. Thick edge is pided into high-speed and low-speed thick edge thick edge to form a thick edge is because the gas knife galvanized angle adjustment caused by poor air blowing, the formation of turbulence generated by appropriately adjusting the intensity air knife can be excluded this defect. 3. If clogging air knife gap will form an air knife marks, require a special cleaning tool to clean up. 4. galvanized steel zinc tablets appearing on the surface, that is, those that are not polished rough small particles, such small particles not only affect the appearance but also affect use. Formation of such particles is because too much zinc production by machines churning bottom ash floated adhere galvanized sheet surface temperature is too high there is so because the production of bottom ash float, in addition, zinc solution high aluminum, aluminum and zinc that have a good affinity, and thus together, adhere to the surface of galvanized sheet.

Galvanized pipe for water belongs to the seam welded steel pipe. Welded steel pipe refers to the steel belt or steel plate bending deformation shapes such as round, square and then welded and jointed on the surface of steel pipe. Welded steel pipe is made of billet is steel plate or strip. Bought from the market pipes, both ends will be color-coded, which means that water uses. Water pipes on blue, red spray hot water pipes, water pipes under the inkjet green, gas pipes and gas meter spray satin, heating pipes whitewashed.  Which galvanized water pipes when the pipe have been banned, because the traditional galvanized pipe rust, corrosive, easy to scale, easy to breed microorganisms produce secondary pollution, the use of a few years, a large amount of rust inside the tube, out of the yellow water not only pollute the ware, and mixed with non-smooth inner wall of the breeding of bacteria, corrosion caused by high levels of heavy metals in water, serious harm to human health.

The welded seamless wrought steel pipe confirms to the standardization of dimensions ASME B36.10M-2004 standards for high or low temperature. The wrought pipe distinguished from steel tube, is applied for pipeline and piping system with tubular products of dimensions. The pipe DN300 has outside diameters numerically larger than corresponding sizes. Oppositely, the tube outside diameter is numerically identical to the size number for all sizes. Welded Seamless Wrought Steel Pipe The pipe size is identified by the nominal pipe size. So the manufacturers of seamless wrought steel pipe are based on the standardized outside diameter. The outside diameter is originally selected so that the pipes would have an inside diameter approximately equal to the normal size with a standard OD and wall thickness. Though there is little relation between standard thickness OD and nominal size, the pipe manufacturer proceeds on the basis of an OD corresponding to the nominal size. ASME B36.10M-2004 Standard covers the standardization of dimensions of welded and seamless wrought steel pipe for high or low temperatures and pressures. The word pipe is used, as distinguished from tube, to apply to tubular products of dimensions commonly used for pipeline and piping systems. Pipe NPS 12 (DN 300) and smaller have outside diameters numerically larger than their corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes. The size of all pipe is identified by the nominal pipe size.The manufacture of pipe NPS 1/8 (DN 6) to NPS 12 (DN 300), inclusive, is based on a standardized outside diameter (OD). This OD was originally selected so that pipe with a standard OD and having a wall thickness that was typical of the period would have an inside diameter (ID) approximately equal to the nominal size. Although there is no such relation between the existing standard thickness — OD and nominal size — these nominal sizes and standard ODs continue in use as “standard”, The manufacture of pipe NPS 14 (DN 350) and larger proceeds on the basis of an OD corresponding to the nominal size.

The strip is into the welded pipe unit and by the multi-channel roll rolling, gradually rolled strip steel, formed with an opening gap round tube, adjust the amount of reduction squeeze rollers, so that the weld gap control for carbon steel pipe in 1 ~ 3mm, and to weld ends flush. If the gap is too large and will result in reduced proximity effect, eddy current lack of heat, poor weld joint between grain yield incomplete fusion or cracking. If the gap is too small, causing the proximity effect increases, excessive soldering heat, causing the weld burning; or weld by extrusion, rolling to form a pit, affecting the quality of the weld surface . 1, welding temperature control, soldering temperature is mainly affected by the impact of high-frequency eddy current heating power, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency but also by the excitation voltage, current and capacitance, inductance. excitation frequency of the excitation circuit of the capacitance and inductance is inversely proportional to the square root, or the voltage and current proportional to the square, as long as the change in the circuit capacitance, inductance, or voltage and current can change the excitation frequency size , so as to control the welding temperature. For low carbon steel , welding temperature control in the 1250 ~ 1460 ℃, can meet the pipe wall thickness 3 ~ 5mm penetration requirements. In addition, the soldering temperature can be achieved by adjusting the welding speed. When the heat input is low, the heated soldering temperatures reach the edge of the weld metal structure remains solid, forming incomplete fusion or penetration; when the input is hot enough, over the edge of the heated seam welding temperature, resulting in burnt or droplet formation of the weld Cave. 2, the extrusion pressure control, both edges of the heating tube to the welding temperature in the extrusion press roll, a common mutual penetration of the metal grains, crystals, and ultimately form a strong weld. If the pressing force is too small, a common number of crystals is small, the weld metal strength decreases, the force will produce cracks; if the extrusion pressure is excessive, the molten weld metal is extruded, not only reduces the the weld strength, and will generate a lot of internal and external burrs , and even cause defects such as seam welding ride. 3, high-frequency induction loop position control High-frequency induction loop should be as close to the squeeze roller position. If the nip roll farther away from the induction coil, the effective heating time is longer, wider heat affected zone, weld strength decreases; contrary, insufficient heating of the weld edge, after extrusion molding failure. 4, the impedance is a magnet or a group of dedicated pipe, the impedance is a cross-sectional area is usually not less than pipe inner cross-sectional area of ​​70%, its role is the induction coil, tube weld edge to form an electromagnetic induction magnet circuit, resulting in the proximity effect, eddy current weld heat concentrated in the tube near the edge, the edge of the tube is heated to soldering temperature. Used impedance dragging a wire within the tube, fixed to its central position should be relatively close to the center of the press roller. Boot, because tube fast motion, the impedance is affected by tube wall friction loss is large, require frequent replacement. 5, the weld after welding and extrusion welding scars will produce, which need to be cleared. Removal method is on the rack cutter, pipe by the rapid movement will burr gelling. Pipe inside burr is generally not cleared.

317 stainless steel pipe and 316 stainless steel pipe are molybdenum stainless steel pipe. Molybdenum content of 317 stainless steel pipe is slightly superior to 316 stainless steel pipe. Because of molybdenum in steel, the steel grade overall function is better than that of 310 and 304 stainless steel pipe, high temperature, when the concentration of sulfuric acid is less than 15% and higher than 85%, the 316 stainless steel pipes are of general use. 316 stainless steel pipe also has the function of the superior and chloride corrosion so can be used in the ocean. 316 stainless steel pipe pole 0.03, the biggest carbon content can be used for welding means less after annealing and the usefulness of the erosion resistance of greatest demand. Erosion resistance, erosion resistance function is better than that of 304 stainless steel pipe, in the process of the fruit of the pulp and paper industry has the function of superior corrosion resistance. And 316 stainless steel pipe industrial atmospheric corrosion of ocean and corrosion resistance. Heat resistance: continuous use under 1600 degrees and 1700 degrees in the following a continuation of the use of 316 stainless steel pipe has good resistance to oxidation function: within the limitations of 800-800 degrees, it is best not to continue the effect of 316 stainless steel pipe, but outside the temperature limitations continued use of 316 stainless steel pipe, the stainless steel pipes has excellent heat resistance. The function of the resistance of 316 stainless steel pipe carbide precipitation is better than 316 stainless steel pipe, can use the temperature limitations. Heat treatment: in 1850-2050 degrees within the temperature limitations of annealing, and agile annealing, and quick cooling. 316 stainless steel pipe means less overheating treatment for hardening. Welding: 316 stainless steel pipe with excellent welding function. All the specification of welding method used for welding. When welding, can according to use, to identify by cb, 316 l, 316 or 316 cb filler rod or electrode of stainless steel pipe welding. To get the best corrosion function, 316 stainless steel pipe steel demand for welding with welding section retreat fire treatment. If use316 stainless steel pipe, not demand for welding retreat fire treatment. Typical use: the pulp and papermaking equipment heat exchange device, dyeing equipment, film washing equipment, pipelines, coastal areas to build things external data. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

How to improve the corrosion resistance of the stainless steel tube, wilsonpipeline pipe industry knowledge to provide the following for your reference: There are many method to improve corrosion resistance of stainless steel tube, such as surface coating a layer of corrosion resistant metal, coating nonmetal layer, electrochemical corrosion protection and change of environmental media, etc. But using the alloying method, improve the corrosion resistance of the material itself is one of the most effective measures to prevent the damage of corrosion, the method is as follows: (1) adding alloying elements, improve the electrode potential of the steel substrate, so as to improve the electrochemical corrosion resistance of stainless steel pipe. General steel adding Cr, Ni, Si more elements can improve the electrode potential. Because Ni is short of, the amount of Si to join can make steel brittle, therefore, only improve the steel substrate electrode potential Cr is common elements. Cr can improve the electrode potential of steel, but it is not a linear relationship. Experiment proved that steel electrode potential with the increase of alloy elements, there is a quantitative change to qualitative change, follow the 1/8 rule. When the Cr content reaches a certain value when the 1/8 atoms (l / 8, 2/8, 2/8…) There will be a mutation, the electrode potential. As a result, almost all of the stainless steel, the Cr content are in 12. % (atomic) above, more than 11.7% (mass). (2) adding alloying elements to form a layer on the surface of the steel stable, complete with steel matrix solid membrane purification. To improve the ability of resistance to chemical corrosion of stainless steel tube. Such as Cr in steels, Si, Al alloy elements, such as surface of stainless steel tube to form a dense Cr2O3, SiO2, Al2O3, such as oxidation film, can improve the corrosion resistance of stainless steel pipe. (3) adding alloying elements to make steel at room temperature can exist in single phase state, reduce the number of micro battery so as to improve the corrosion resistance of steel. Like to join a sufficient number of Cr or Cr – Ni, single-phase ferritic steel at room temperature to obtain or single phase austenite. (4) to join the elements such as Mo, Cu, improve the ability of corrosion resistance. (5) join Ti, Nb elements, such as elimination of Cr intergranular segregation, thus reduce the tendency to intergranular corrosion. (6) to join the Mn, N elements, such as single-phase austenitic organization instead of part of the Ni, at the same time can greatly improve the corrosion resistance of stainless steel pipe in organic acids. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In strong oxidizing nitric acid, compared with high alloy steel containing molybdenum, low corrosion resistance. In hydrochloric acid, the use of 904L stainless steel pipe is limited to a lower concentration of 1-2%. In this concentration range. The corrosion resistance of 904L stainless steel pipe is better than the conventional stainless steel. 904L stainless steel pipe has a high resistance to pitting corrosion. In chloride solution, the corrosion resistance is also very good. 904L stainless steel pipe with high nickel content, reduce the corrosion rate in the pit and crevice. When the ordinary austenitic stainless steel is more than 60 degrees Celsius, it may be sensitive to stress corrosion in a chloride rich environment. Due to the high nickel content, 904L stainless steel pipe in the chloride solution, concentrated hydroxide solution and the rich hydrogen sulfide environment, has a high resistance to stress corrosion cracking capacity. Because the 904L carbon content is very low (maximum 0.020%), there will be no carbide precipitation in the case of general heat treatment and welding. This eliminates the general heat treatment and the risk of intergranular corrosion after welding. As a result of the high chromium nickel molybdenum content, and added a copper element, so the 904L stainless steel pipe even in the reducing environment, such as sulfuric acid and formic acid can also be passive. The high nickel content also has a lower corrosion rate in the active state. In the 0~98% concentration range of pure sulfuric acid, the use of 904L temperature can be as high as 40 degrees celsius. The corrosion resistance of pure phosphoric acid is very good in the range of 0~85% concentration. In the industrial phosphoric acid produced by the wet process, the impurities have a strong influence on the corrosion resistance. In all kinds of phosphoric acid, the corrosion resistance of 904L stainless steel pipe is better than that of ordinary stainless steel pipe. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

What is the difference between cold rolling stainless steel angel bar and hot rolled stainless steel angel bar? Cold-rolled stainless steel angel bar and hot rolled stainless steel angel bar is respectively using two different rolling cold rolled and hot rolled and rolled stainless steel angel bar. The difference between the two is: 1, the stainless steel cold rolling forming angel bar to allow local buckling section, which can make full use of the angel bar buckling bearing capacity after; The hot rolled stainless steel local buckling angel bar are not allowed to cross section. 2, hot rolled stainless steel angel bar free torsional rigidity is higher than cold-rolled stainless steel angel bar, so hot rolled stainless steel angel bar of torsion performance is superior to cold rolled stainless steel angel bar. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Casing pipe is important to oil drilling equipment, and its main equipment includes drill, core pipe and casing, drill collars and drilling small diameter steel pipe and so on. The casing pipe is used to support oil and gas wall of the pipe, to ensure that the drilling and completion of the process of the normal operation of the wells. Depending on the drilling each well depth and geological conditions, to use several layers of casing. Casing cementing go down after using it with tubing, drill pipe are different, can not be reused, a one-time consumable materials. Therefore, the total consumption of the casing is 70% of the oil well pipe. Casing can be pided according to usage: catheter, surface casing, casing and production casing. Casing pipe is a large-diameter pipe, play a fixed oil and gas wells, or wellbore wall effect. The casing pipe is inserted into the well hole, fixed with cement to prevent the formation and borehole spaced borehole collapse and to ensure circulation of the drilling mud to the drilling mined. Casing pipe is mainly used for drilling oil wells during drilling and after completion of the support wall to ensure that the conduct of the drilling process and completion of the wells after the regular oil casing normal operation. OCTG mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drilling pipe, oil casing, pump tubing. Oil drill pipes are mainly used to connect the drill collar and drill and pass drilling power. Casing pipe is mainly used for drilling and completion of the right wall of the support, to ensure that the conduct and completion of the drilling process after the normal operation of the wells. Pumping wells at the bottom of the tubing will mainly oil, gas transported to the ground. Casing pipe is to maintain the wells run lifeline. As different geological conditions, underground complex stress state, pulling, pressing, bending, torsional stress acting on the combined effect of the tube, which the casing itself, the quality of the higher requirements. Once the casing itself is damaged for some reason, could lead to the whole production wells, or even scrapped.

Galvanized coating has a number of characteristics that make it a well-suited corrosion protective coating for iron and steel products in most environments. Th excellent field performance of Galvanized coating results from its ability to form dense, adherent corrosion product films of corrosion considerably below that of ferrous materials (some 10 to 100 times slower depending upon the environment). While a fresh zinc surface is quite reactive when exposed to the atmosphere, a thin film of corrosion products develops rapidly, greatly reducing the rate of further corrosion. In addition to creating a barrier between steel and the environment, zinc also has the ability to cathodically protect the base metal. Zinc, which is anodic to iron and steel, will preferentially corrode and protect the iron or steel against rusting when the coating is damaged. Many different types of zinc and each has unique characteristics. These characteristics not only affect applicability but also the relative economics and expected service life.The method of processing, adhesion to the base metal, protection aff orded at corners, edges, and threads, hardness, coating density, and thickness can vary greatly among the diff erent coatings.This is practical aid discusses each of the major types of zinc coatings, applied by batch hot-dip galvanizing, continuous sheet galvanizing,electro galvanizing, zinc plating, mechanical plating, zinc spraying, and zinc painting, to help specialists assess and select zinc coatings for corrosion protection. After deciding to use a Galvanized coating for corrosion protection, some factors must be considered to ensure the proper coating is selected for the intended application and service environment. Obviously, zinc coating processes which are limited to small parts, and operations limited to continuous lines in steel mills (i.e. continuous galvanizing and electrogalvanizing) cannot be considered for the protective coating of structural steel members. Each Galvanized coating reviewed provides various degrees of corrosion protection. When selecting a coating, it is important to investigate the corrosiveness of the exposure environment to ensure the Galvanized coating selected will provide adequate service life for the cost.

Galvanizing: also called hot dip zinc and hot galvanizing, is an effective way of metal corrosion protection, mainly used for metal structure industry facilities. around 500 ℃ after rust removal of steel in zinc melt liquid, make the zinc layer is adhered on the surface of the steel members, thereby the purpose of anticorrosive. Cold galvanized (galvanizing) also called electro-galvanized cold galvanizing, which is the use of the pipe member through electrolysis degreasing, pickling, and put into a solution composed of zinc and a cathode connected to the electrolytic apparatus, placed opposite the tube member zinc plate, connected to the electrolysis the positive power equipment, the use of electric current from the positive to the negative directional movement will be in a layer of zinc deposited on pipe fittings, cold-plated fittings are galvanized after processing the first. Cold galvanizing paint mainly through electrochemical principles for corrosion, it is necessary to ensure full contact of zinc powder and steel, generating electrode potential difference, so the steel surface treatment is very important. Cold galvanizing process is used to protect the metal against corrosion, for the use of filler coatings of zinc, in the use of any method to a coating applied to the surface to be protected, the filler form zinc coating after drying, the dried coating having a content of zinc (95%). Suitable for repair work (ie work in the repair process, the only damage to the steel surface to be protected place, as long as the repaired surface can be re-coated). Cold galvanizing process for a variety of steel products and structures corrosion. (Cold galvanizing is galvanized, galvanized rarely, and only 10-50g/m2, its own hot-dip galvanized corrosion resistance than a lot of difference. Using galvanized the price is relatively cheaper. The difference between hot dip galvanized and cold galvanizing: 1, anticorrosive, hot dip galvanized is dozens of times of cold galvanizing. 2, vary in their manner of operation: hot dip galvanized is in 450-480 degrees of molten liquid zinc in zinc plating, plating is cold at room temperature by electroplating of zinc plating or other methods. 3, galvanized layer thickness is different, hot dip galvanized thickness is much larger than cold galvanizing. 4, surface smoothness, cold galvanized than galvanized smooth good-looking appearance. 5, the price is different, hot dip galvanized cold galvanizing. 6, cold galvanized can only side plating, hot dip galvanized for plating. 7, adhesion, adhesion of cold galvanizing is inferior to hot dip galvanized. 8, fee standards is different, hot dip galvanized according to the thickness of the material fee, cold most of the plating charge according to square meters. Hot galvanizing technology mainly use range: industry, construction, electric power, chemical industry, machinery manufacturing, petroleum, municipal facilities, agricultural facilities, communication facilities, fire facilities, railway, highway and transportation facilities and other fields.

low temperature carbon steel pipe is medium carbon structural steel, cold steel plus low energy are good with good mechanical properties, and low prices, wide sources, so widely used. Its biggest weakness is the low hardenability, cross-sectional dimensions Japan is relatively high workpiece should not be used. Cold steel for low temperature operation, can withstand a certain low temperature impact. Low temperature quench pipe A3 + (30 ~ 50) ℃, in practice, is usually set to the upper limit. High quenching temperature to low temperature pipe heating speed, reduce surface oxidation, and can improve efficiency. The workpiece is uniform austenite, will require sufficient holding time. If the actual installed furnace capacity, would be appropriate to extend the holding time. Otherwise, there may be insufficient due to uneven heating caused by the hardness of the phenomenon. However, the holding time is too long, will also appear coarse grains, oxidation and decarbonization serious ills affecting quenching quality. We believe that such equipment is greater than the specified process documents furnace, the heating need to extend the holding time of 1/5. Because the low temperature steel hardenability is low, it should be large cooling rate of 10% salt solution. After the workpiece into the water, it should hardenability, but not chilled, if in cold salt water penetration, it is possible cracking of the workpiece, it is because when the workpiece is cooled to about 180 ℃, the rapid transformation of austenite horse s body tissue caused by excessive stress due. Therefore, when hardened steel rapid cooling to the low temperature region, it should take slow cooling method. As the water temperature is difficult to grasp, accountable experience to operate, when to stop dithering artifacts in the water, the water can be air-cooled (eg oil cooler can be better). In addition, the work should move into the water should not be static, should be in accordance with the geometry of the workpiece, as the rules of sport. Stationary cooling medium plus stationary workpiece, resulting in uneven hardness, stress uneven leaving large deformation of the workpiece, and even cracking. Cold steel pieces quenched hardness after quenching should reach HRC56 ~ 59, lower section of the possibility of some large, but not less than HRC48, otherwise, it shows the work has not been fully hardened tissues may occur even ferrite sorbitic Organizations, such organizations tempered, still retained in the matrix, which was not quenched purposes. Cryogenic tempering steel after quenching, the heating temperature is usually 560 ~ 600 ℃, hardness is HRC22 ~ 34. Because the goal is to get quenched mechanical properties, so the relatively wide range of hardness. But drawing hardness requirements, it is necessary to adjust by drawing tempering temperature to ensure hardness. For example, some cold steel shafts require high strength, hardness is high; while some gear, shaft parts with keyway, because after quenching but also for milling, insert processing, hardness requirements will be lower. About Tempering time, depending on the hardness and size of the piece, we think, depends on the hardness after tempering tempering temperature, tempering time with little to do, but must return through the general overall at the workpiece Tempering Time more than one hour.