The individual quality spiral welded pipe is relatively large, so it is necessary to be placed outdoors. However, this will be difficult to avoid the sun and rain, the rust has been plagued spiral welded pipe storage time and conditions. We need to conduct a comprehensive answer on rust knowledge of spiral welded pipe.
The main method is to use steel wire to brush the surface grinding, cleaning and preheating the spiral welded pipe can remove or loose or tilt of the oxide scale, rust and welding slag. Hand tool rust can reach Sa2 level, power tools rust can be achieved Sa3 level, if attached to a solid steel sruface oxide skin, tools rust effect is not ideal which can not reach the anchor pattern depth of anti-corrosion construction requirements.
Pickling by solvent or emulsion can clean low pressure liquid delivery pipe surface. It can achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, scale, welding flux etc.
General chemical and electrolytic picking are two ways to do, pipeline corrosion using only chemical pickling can descaling, rust, old coatings, and sometimes used as a sand-blasting after reprocessing. Although chemical cleaning the surface can reach a certain cleanliness and roughness, the anchor pattern shallow, and easy to pollute the environment stacking spiral welded pipe.
When the rational use of means to clean rusty pipe and fittings, we guarantee long service in production, creating more production efficiency.
2019年7月11日星期四
2019年7月10日星期三
Professional Skills of Straight Seam Double Submerged Arc Welded Steel Pipe
Professional skills of straight seam double submerged arc welded steel pipe(lsaw steel pipe) are following below:
1, Double submerged arc welding method in a new invention in 1940, in front of it and the manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating. Straight seam double submerged arc welding and manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating, specifically melting out of the flux. Flux The flux system consists of a funnel filled through a pipeline to be welded to the front.
2. The second difference is the use of electrode using wire, because wire can be continuously sent; electrodes, we burn a welding electrode must have a head gave threw it, and the operation had to stop, and then change the electrode welding.
3. In this way, the first advantage is fully automated; second advantage, which is under the submerged arc welding, so its heat exchange and protection of relatively strong performance, high quality weld out; third advantage, since the automatic submerged arc welding arc buried under welding flux, so it can use high-current, high welding efficiency, the recent progress of our country natural gas pipeline project.
4, Later changed to the wire, with the wire feed unit and wire spool is continuously sent to the wire, the welding wire is continuously fed, igniting an arc in the meltable particulate flux covering, welding wire, part of the melting and evaporation of the base metal and solder forms a cavity, the arc is stabilized combustion cavity inside, so call it submerged arc welding. Arc is buried in the inside of the cavity.
5, The pipe is a high-strength steel, such pipelines in the factory inside the first preformed section, and then get on the site, in the field of welding, the welding process such pipelines in factory production is the use of submerged arc welding, now buried welding has developed into, a double wire submerged arc welding, as well as multi-wire submerged arc welding, to further improve efficiency.
1, Double submerged arc welding method in a new invention in 1940, in front of it and the manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating. Straight seam double submerged arc welding and manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating, specifically melting out of the flux. Flux The flux system consists of a funnel filled through a pipeline to be welded to the front.
2. The second difference is the use of electrode using wire, because wire can be continuously sent; electrodes, we burn a welding electrode must have a head gave threw it, and the operation had to stop, and then change the electrode welding.
3. In this way, the first advantage is fully automated; second advantage, which is under the submerged arc welding, so its heat exchange and protection of relatively strong performance, high quality weld out; third advantage, since the automatic submerged arc welding arc buried under welding flux, so it can use high-current, high welding efficiency, the recent progress of our country natural gas pipeline project.
4, Later changed to the wire, with the wire feed unit and wire spool is continuously sent to the wire, the welding wire is continuously fed, igniting an arc in the meltable particulate flux covering, welding wire, part of the melting and evaporation of the base metal and solder forms a cavity, the arc is stabilized combustion cavity inside, so call it submerged arc welding. Arc is buried in the inside of the cavity.
5, The pipe is a high-strength steel, such pipelines in the factory inside the first preformed section, and then get on the site, in the field of welding, the welding process such pipelines in factory production is the use of submerged arc welding, now buried welding has developed into, a double wire submerged arc welding, as well as multi-wire submerged arc welding, to further improve efficiency.
2019年7月3日星期三
Seamless steel tube rolling
The raw material is rolled seamless round tube, tube embryos to go through a cutting machine cutting a length of about 1 meter blank, and by conveyor belt to the furnace heating. The billet is fed into the furnace is heated to a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is the key issue. After a round tube came out to go through the pressure punching machine wear air. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding capacity, can be worn a variety of steels. After perforation, round tube has been three-roll rolling, rolling or extrusion. To post extrusion detached sizing. Sizing high-speed rotary cone drill bit through the perforated steel embryo formed steel. Pipe inner diameter is determined by the outer diameter sizing mill drill length.
Pipe by sizing after entering the cooling tower through spray cooling pipe after cooling, will be straightening. After straightening the steel conveyor belt to the metal detection machine (or pressure test) for internal testing. If the thick-walled seamless internal cracks, bubbles and other issues, will be detected. After the selection of steel but also through strict quality control manual. After the steel quality inspection, using spray paint on number, size, production batch number. By a crane into the warehouse.
Pipe by sizing after entering the cooling tower through spray cooling pipe after cooling, will be straightening. After straightening the steel conveyor belt to the metal detection machine (or pressure test) for internal testing. If the thick-walled seamless internal cracks, bubbles and other issues, will be detected. After the selection of steel but also through strict quality control manual. After the steel quality inspection, using spray paint on number, size, production batch number. By a crane into the warehouse.
Effect of nitrogen on corrosion resistance of stainless steel
1. Influence on the microstructure of stainless steel
The effect of nitrogen on stainless steel is very strong. The nitrogen element in the stainless steel matrix can replace part of the nickel element, reduce the ferrite content in the stainless steel, help stabilize the austenite, reduce the precipitation of harmful intermetallic phases, and even eliminate the martensite transformation during cold working.
2. Influence on mechanical properties of stainless steel
The effect of nitrogen on the mechanical properties of the matrix in stainless steel is mainly reflected in two aspects. First of all, nitrogen can significantly increase the strength of stainless steel, and will not reduce the plastic toughness of stainless steel. This is a good study of the direction of high strength and toughness of stainless steel. Secondly, the nitrogen element can also enhance the creep resistance, fatigue resistance and wear resistance of the stainless steel.
3. Influence on corrosion resistance of stainless steel
Nitrogen is also beneficial for increasing the corrosion resistance of stainless steel. Mainly to improve the resistance to intergranular corrosion, pitting corrosion, crevice corrosion. The mechanism of nitrogen resistance to pitting corrosion and crevice corrosion of stainless steel is mainly acid consumption theory. Nitrogen forms NH4+, lowers pH value, prevents anode dissolution and slows local acidification, which can inhibit the autocatalytic process of pitting corrosion. Secondly, the enrichment of interfacial nitrogen, the enrichment of nitrogen in the passivation film of the metal interface near the metal side, will affect the repassivation kinetics, promote the rapid re-passivation of the stainless steel surface, and thus play a role in suppressing pitting corrosion. In addition, nitrogen and other elements can work synergistically. Nitrogen can inhibit the over-passivation and dissolution of elements such as chromium and molybdenum, and can produce a stronger surface layer in the local corrosion process of the stainless steel plate surface, and improve the corrosion resistance of the stainless steel plate surface.
Nitrogen plays an indispensable role in the stability and corrosion resistance of stainless steel, and since nitrogen is cheaper than alloying elements such as nickel and chromium, the future development space in the field of stainless steel should have unlimited potential.
http://www.xysteelpipe.com/info/Effect-of-nitrogen-on-corrosion-resistance-of-stainless-steel-1447-1.htm
The effect of nitrogen on stainless steel is very strong. The nitrogen element in the stainless steel matrix can replace part of the nickel element, reduce the ferrite content in the stainless steel, help stabilize the austenite, reduce the precipitation of harmful intermetallic phases, and even eliminate the martensite transformation during cold working.
2. Influence on mechanical properties of stainless steel
The effect of nitrogen on the mechanical properties of the matrix in stainless steel is mainly reflected in two aspects. First of all, nitrogen can significantly increase the strength of stainless steel, and will not reduce the plastic toughness of stainless steel. This is a good study of the direction of high strength and toughness of stainless steel. Secondly, the nitrogen element can also enhance the creep resistance, fatigue resistance and wear resistance of the stainless steel.
3. Influence on corrosion resistance of stainless steel
Nitrogen is also beneficial for increasing the corrosion resistance of stainless steel. Mainly to improve the resistance to intergranular corrosion, pitting corrosion, crevice corrosion. The mechanism of nitrogen resistance to pitting corrosion and crevice corrosion of stainless steel is mainly acid consumption theory. Nitrogen forms NH4+, lowers pH value, prevents anode dissolution and slows local acidification, which can inhibit the autocatalytic process of pitting corrosion. Secondly, the enrichment of interfacial nitrogen, the enrichment of nitrogen in the passivation film of the metal interface near the metal side, will affect the repassivation kinetics, promote the rapid re-passivation of the stainless steel surface, and thus play a role in suppressing pitting corrosion. In addition, nitrogen and other elements can work synergistically. Nitrogen can inhibit the over-passivation and dissolution of elements such as chromium and molybdenum, and can produce a stronger surface layer in the local corrosion process of the stainless steel plate surface, and improve the corrosion resistance of the stainless steel plate surface.
Nitrogen plays an indispensable role in the stability and corrosion resistance of stainless steel, and since nitrogen is cheaper than alloying elements such as nickel and chromium, the future development space in the field of stainless steel should have unlimited potential.
http://www.xysteelpipe.com/info/Effect-of-nitrogen-on-corrosion-resistance-of-stainless-steel-1447-1.htm
2019年7月2日星期二
Welding process of straight seam welded pipe
Longitudinal straight seam welded pipe butt weld joint cross-sectional shape, depending on the thickness of the body to be welded before welding groove and then type two sides. When welding thick steel plate, for penetration in contact at the edges out of various shapes of the groove, so that more easily into the welding rod or wire. Groove patterns are one-sided welding the welding groove and the sides of the groove. When you select groove type, in addition to outside should be considered to ensure penetration welding convenient, less filler metal Chi, small welding deformation and beveling of Longitudinal low cost factor.
Linker connecting the two is in the welding Longitudinal seam formed called weld. Both sides of the weld in the welding welding heat effect will be, but the organization and performance vary, this area is known as the heat affected zone. Welding due to the workpiece material welding materials, Longitudinal welding current so different, after welding may occur in the weld and heat affected zone of overheating, embrittlement, hardening or softening, but also the weldment performance degradation, deterioration of weldability. This need to adjust the welding conditions, before welding weldment interface preheating, post-weld heat when and weld heat treatment can improve the quality of welding weldment quality.
Longitudinal is of two or more homogeneous or heterogeneous material through a combination of diffusion and the question of the atom or molecule is integrally connected to the process, prompting the question of atoms and molecules produce binding and diffusion method is to heat or pressure, or simultaneously heated and pressurized.
In addition, a local weld foot rapid heating and cooling process, the weld zone due to the binding body and four weeks of the workpiece can not freely expand and contract in the weldment after cooling will produce welding stress and deformation. Important product after welding is required to eliminate welding stress, welding distortion correction.
Linker connecting the two is in the welding Longitudinal seam formed called weld. Both sides of the weld in the welding welding heat effect will be, but the organization and performance vary, this area is known as the heat affected zone. Welding due to the workpiece material welding materials, Longitudinal welding current so different, after welding may occur in the weld and heat affected zone of overheating, embrittlement, hardening or softening, but also the weldment performance degradation, deterioration of weldability. This need to adjust the welding conditions, before welding weldment interface preheating, post-weld heat when and weld heat treatment can improve the quality of welding weldment quality.
Longitudinal is of two or more homogeneous or heterogeneous material through a combination of diffusion and the question of the atom or molecule is integrally connected to the process, prompting the question of atoms and molecules produce binding and diffusion method is to heat or pressure, or simultaneously heated and pressurized.
In addition, a local weld foot rapid heating and cooling process, the weld zone due to the binding body and four weeks of the workpiece can not freely expand and contract in the weldment after cooling will produce welding stress and deformation. Important product after welding is required to eliminate welding stress, welding distortion correction.
Disadvantages of galvanized low carbon steel
Disadvantages of galvanized mild steel has following aspects:
On the surface of hot dip galvanized steel rice distribution classes of small dots, called zinc particles is customary. Defective zinc particles can be divided into two: one is up and down the strip surface adhesion lot of granular, strip local increase in the thickness of the zinc layer, causing the surface rough, unsightly and harmful use of known zinc particles. There are two forms, one of the larger particles of zinc tablets, the main ingredient is iron - zinc compound, which is the end of slag.
When coated galvanized steel edge is much higher than the middle of coating thickness, edge thickness is produced.
When the air knife nozzle clogging occurs locally when in a position corresponding to the strip will produce thick zinc layer is formed with marks.
In the middle of the strip edge or rendered bright stripes or the presence of dendritic conchoidal crystal crystalline zinc this particular often make local zinc layer projections, it is called zinc projections. Strip out from uncoiler to galvanized defects between coiler, strip and a mechanical relative movement generated.
On the surface of hot dip galvanized steel rice distribution classes of small dots, called zinc particles is customary. Defective zinc particles can be divided into two: one is up and down the strip surface adhesion lot of granular, strip local increase in the thickness of the zinc layer, causing the surface rough, unsightly and harmful use of known zinc particles. There are two forms, one of the larger particles of zinc tablets, the main ingredient is iron - zinc compound, which is the end of slag.
When coated galvanized steel edge is much higher than the middle of coating thickness, edge thickness is produced.
When the air knife nozzle clogging occurs locally when in a position corresponding to the strip will produce thick zinc layer is formed with marks.
In the middle of the strip edge or rendered bright stripes or the presence of dendritic conchoidal crystal crystalline zinc this particular often make local zinc layer projections, it is called zinc projections. Strip out from uncoiler to galvanized defects between coiler, strip and a mechanical relative movement generated.
Pipeline inspection of welded steel pipe
Welded steel pipe at the factory to go through rigorous testing to ensure the quality of welded compliance standards and user requirements. Pipe inspection items generally include: appearance quality factory inspection project, straightness, dimensions, and other types of weld quality inspection items (flattening, flaring, bending, etc.). Welded pipe surface quality and straightness inspection by a full-time quality inspector confirmed finishing process pipe segment using visual way, the implementation of the detection test dimensions available random sampling method, and the weld quality inspection shall be made on special equipment by root on line. This article focuses on online testing of the weld. At present, about our national standards, testing methods available weld pipe hydrostatic testing, ultrasonic testing, eddy current testing in any way.
Hydrostatic test is the most common, the most direct and reliable weld line inspection
Measured way, in a variety of hydraulic test machine. When the pressure test, through the first low-pressure water, filled the whole steel pipe to make the air side by side, and then to test pressure specified by the pressurized way, and to stabilize the prescribed time, when there is no pipe welds and around wet, spray, leakage or permanent deformation is considered qualified.
When the metal by an alternating magnetic field is induced metal surface
Eddy currents; when the presence of the metal surface defects, since the impedance increases, the eddy current value becomes smaller; and when no defect of a metallic material, the value of the stable vortex; size of the power according to the eddy current loss, can be characterized metals whether the surface defects.
Ultrasonic wave propagation in the process, will have a reflection on the media surface.
If there is a crack pipe welds, weld, false welding, lap welding defects such as acoustic impedance will change significantly, so that ultrasonic generating different reflection, through a dedicated instrument will be identified to achieve the purpose of flaw detection. The main steel tube ultrasonic flaw detection are: rotating the probe, steel straight forward; probe fixed, steel rotating forward; steel rotating probe straight forward three forms, in the production of different pipe diameter in both applications.
Hydrostatic test is the most common, the most direct and reliable weld line inspection
Measured way, in a variety of hydraulic test machine. When the pressure test, through the first low-pressure water, filled the whole steel pipe to make the air side by side, and then to test pressure specified by the pressurized way, and to stabilize the prescribed time, when there is no pipe welds and around wet, spray, leakage or permanent deformation is considered qualified.
When the metal by an alternating magnetic field is induced metal surface
Eddy currents; when the presence of the metal surface defects, since the impedance increases, the eddy current value becomes smaller; and when no defect of a metallic material, the value of the stable vortex; size of the power according to the eddy current loss, can be characterized metals whether the surface defects.
Ultrasonic wave propagation in the process, will have a reflection on the media surface.
If there is a crack pipe welds, weld, false welding, lap welding defects such as acoustic impedance will change significantly, so that ultrasonic generating different reflection, through a dedicated instrument will be identified to achieve the purpose of flaw detection. The main steel tube ultrasonic flaw detection are: rotating the probe, steel straight forward; probe fixed, steel rotating forward; steel rotating probe straight forward three forms, in the production of different pipe diameter in both applications.
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