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(1) welding methods: due to the majority of stainless steel pipes and sizes, according to the welding characteristics of stainless steel, as far as possible, reduce the amount of heat input, the manual electric arc welding, argon arc welding is adopted two kinds of methods, d > 159 mm Φ adopts argon arc welding, manual arc welding covering. D ≦ Φ 159 mm all use argon arc welding. The welding machine adopts the manual arc welding/argon arc welding of the WS7-400 inverter arc welding machine. (2) the welding material: austenitic stainless steel is special steel, to meet the joint with the same performance, should follow the principle of “the composition such as” to choose the welding material, at the same time to strengthen the joint between the thermal crack and corrosion ability, make a small amount of ferrite appear in the joint, choose HooCr19Ni12Mo2 argon arc welding with welding wire, hand arc welding with electrode CHSO22 as filling material, its composition is shown in table 1 and table 2. Table 1 chemical composition of welding wire HOOCr19Ni12Mo2 (%) C Si Mn P S Ni Cr Mo 0.012 0.13 1.70 0.019 0.007 13.23 18.72 2.38 Table 2 chemical composition of welding rod CHS022 (%) C Cu Si Mn P S Ni Cr Mo 0.03 0.20 0.64 0.75 0.02 0.007 11.77 19.66 2.05 (3) welding parameter. The outstanding feature of austenitic stainless steel is that it is sensitive to overheating, so it is necessary to control the interlayer temperature strictly under the condition of small current and fast welding, and the interlayer temperature is less than 60 degrees. (4) Groove form and assembly position welding. Using V groove, groove form with lower welding current, penetration is small, thus groove blunt edge is smaller than carbon steel, approximately 0-0.5 mm, groove Angle is bigger than carbon steel, which is about 65 ° to 700 °. Due to the large thermal expansion coefficient of stainless steel, the welding stress can be produced when welding, and strict positioning welding is required. For d ≦ Φ 89 mm tube adopts two positioning, d = Φ 89 – Φ 219 mm USES three positioning, d ≧ 219 mm by four o ‘clock positioning; Position weld length 6-8 mm. (5) Welding technical requirements: 1. The welding machine adopts dc inverse when manual arc welding, and dc is used when argon arc welding. 2. Before welding, the wire should be brushed with stainless steel wire to remove the oxide skin of the surface and clean with acetone. Electrode should be in 200-250 ℃ drying 1 h, as you take; 3. Before welding, clean the oil on both sides of the slope of the workpiece by 25 mm, and wash the sides of the slope with acetone. 4. Argon arc welding, the nozzle Φ 2 mm in diameter, extremely rich tungsten tungsten electrode, specifications Φ 2.5 mm; 5. When the argon arc welding stainless steel, the back must be protected by argon gas to guarantee the back forming. The flow rate is 5-14l/min, and the positive argon flow rate is 1213l/min. The seam thickness should be as thin as possible at the bottom of the bottom welding, and it should be in good shape with the root, and the arc should be formed in a gentle slope. If the arc is retracted, the grinding machine will be worn out. The arc must be filled in the groove and the arc crater should be filled to prevent the cracks. Due to the stainless steel to austenitic stainless steel, to prevent the carbide precipitation sensitization and intercrystalline corrosion, should strictly control the interpass temperature and cooling rate after welding, the welding interlayer temperature control under 60 ℃, must immediately after welding water-cooled, by subsection welding at the same time. The specific section method is shown in figure 1. This symmetrical dispersion welding sequence can increase the cooling speed of the connector and reduce the welding stress. Figure 1. Welding schematic of different pipe diameters 2 the results (1) the appearance inspection has no porosity, welding tumor, sag and biting edge etc., forming well. (2) to stretch and bend test pieces, all mechanical property indexes meet the requirements, and no defects such as fusion and cracks are found. (3) macroscopic metallographic examination, found that the weld bead was well fused, and the penetration was 1-1.5mm. Microscopic metallographic examination, parent material and the heat affected zone is all austenitic organization, weld metal for ten ferrite austenite (4%) of the organization, fully meet the requirements of intergranular corrosion resistance and resistance to brittle, after incoalation company site construction to ensure the welding quality. Source: China 316L Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel welded pipe is mainly used in landscape decoration, light industry, pharmaceutical industry, water supply and other industries. It is also applied to petrochemical industry. It usually selects medium and low pressure pipelines above the size of 159mm. Besides, the automobile muffler can also be made of stainless steel welded pipe. Stainless steel seamless pipes are mainly used in chemical industry, fertilizer, chemical fiber (three), oil, power boilers, machinery, aerospace, nuclear industry, defense industry and other demanding industries. Oil drilling can be made of stainless steel pipes, stainless steel non-magnetic drill collar, high resistance CO, CO2 and Cl- corrosion super ferrite stainless steel Cr13, Cr25 and other oil and casing are used in oil field drilling, but most of such stainless steel pipes still rely on imports. Stainless steel pipe for thermal power boilers Heat – resistant and stainless steel austenitic steel boiler tubes are used in thermal power boilers. 1 tons of 600 thousand kW supercritical thermal power unit boiler need 200-500 tons of rust resistant steel tube, which is also more dependent on import. “Three” industrial use of heat-resistant stainless steel tubes The heat resistant stainless steel pipe is mainly used for heat exchange and fluid transportation in the “three industry”. The market capacity is the largest, and the domestic market demand is about 160 thousand tons per year. And the requirements of this kind of stainless steel pipes are very strict, and it is also necessary to meet the requirements of the import. The potential market is used to transport oil pipe pipe and low temperature cracking furnace of large diameter, heat and corrosion resistance because of its special requirements and equipment installation and maintenance inconvenience, and requirements of equipment life cycle is long, through the material properties and performance optimization control of material composition and special heat treatment. The other potential market is the special steel pipe for the fertilizer industry (urea and phosphate), the main steel types are 316Lmod and 2RE69. At present, the above stainless steel tubes are basically imported. Duplex stainless steel pipes (fluid, heat exchanger) The duplex stainless steel is mainly used in chemical and chemical fertilizer fields. Its characteristics are good stress corrosion resistance and the application temperature is less than 350 degrees C. Because of its high strength, resistance to stress, corrosion resistance and economy, duplex stainless steel pipes are now used in the manufacture of heat exchangers and fluid tubes. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When the stainless steel elbow is corroded, a special cleaning agent is needed to remove the rust. And in the daily use of the regular cleaning. For example, when it is found that the surface of stainless steel elbow is dusty or easier to remove, it can be cleaned directly with warm water or weak detergent. Of course, soapy water is also acceptable. And when the surface of the stainless steel elbow is covered with trademark or sticky film, it can also be washed with weak detergent. The last thing to pay attention to is to rinse clean with water and dry cotton cloth to dry. When installing the stainless steel elbow, it can be installed directly on the corresponding pipe according to the connection mode, and it is installed according to the position used. Usually, the stainless steel pipe can be installed at any position of the pipeline, but it also needs good operation experience. Attention should be paid to that the medium flow direction of the cut-off stainless steel elbow should be upward under the longitudinal valve, and the stainless steel elbow can only be installed horizontally. When the stainless steel elbow is installed, it needs to ensure good sealing performance, avoid leakage and affect the normal operation of stainless steel pipe. The elbow is made of stainless steel because of its high corrosion resistance. Stainless steel materials are also one of the most powerful materials in the metal materials used in building. It is because of the excellent corrosion resistance of the stainless steel that it enables structural components to maintain the integrity of the engineering design for a long time. Chromium stainless steel also has good mechanical strength and high elongation. It is easy to be processed into various components, which can fully meet the needs of architects and structural designers. All metals react with the oxygen in the atmosphere and produce a chrome oxide film on the stainless steel plate. The corrosion resistance of stainless steel is mainly influenced by the alloy elements in the steel. The chrome is made of stainless steel material to obtain good resistance to corrosion of the basic elements, when the chromium content in the stainless steel up to about 1.2%, chromium and corrosion will occur oxidation, produce a very thin layer of oxide film on the surface of stainless steel substrate, the film can prevent the further corrosion of steel. Besides chromium, the commonly used alloying elements include nickel, molybdenum, titanium, niobium, copper and nitrogen, which can fully meet the requirements for the structure and properties of stainless steel under various uses. Stainless steel material in the stainless steel elbow is a kind of interstitial solid solution formed in gamma -Fe, such as chromium and nickel, and belongs to a class of major stainless steel types. Its main characteristics are: there are at room temperature in non-magnetic austenite, its yield is relatively low, the plastic is relatively good, good welding performance, easy to exercise and hot forging forming; component characteristics it is contains a lot of chromium, nickel and other corrosion resistance elements, for example molybdenum, niobium and titanium. Source: China Stainless Steel Elbows Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel sheet is widely used. The surface modification of sheet metal is a low-cost way and can significantly enhance the hardness and wear resistance of materials. Because the surface oxide film of the stainless steel plate will exist, it is very difficult to make ordinary gas nitriding. Although the surface activated stainless steel can be processed by gas nitriding, the process is complex and difficult to control. Therefore, some new nitriding processes have been used in the industry. Ion nitriding technology is the most used one. Conventional ion nitriding is carried out in a mixed atmosphere of N2 and H2 or NH3 at the temperature of 500 to 560. Because plasma nitriding can directly remove the passive film on the surface of stainless steel, and it is easy to achieve local nitriding and easier control of nitrogen potential. It can show obvious superior performance in stainless steel surface reinforcement. The results of nitriding experiments for some martensitic stainless steels show that plasma nitriding can produce a certain thickness of nitriding layer on the surface of stainless steel plates, and there is no need to remove the oxide film pretreatment. The hardness and wear resistance of the stainless steel after nitriding will be obviously enhanced. However, conventional ion nitriding is easy to form CrN on stainless steel surface, resulting in poor chromium formation on stainless steel substrate, thus reducing the corrosion resistance of stainless steel. Therefore, even if the ion nitriding treatment of stainless steel surface hardness, wear resistance and abrasion resistance, bonding ability has increased greatly, but if handled properly, very easy to produce surface peeling, hardening layer of uneven thickness and corrosion resistance greatly reduced the quality problems. In order to prevent the formation of CrN at high temperature and damage the original corrosion resistance of stainless steel, it is necessary to develop a low temperature treatment process. The plasma low temperature nitriding process developed in the 80s of last century has successfully tackled the technical difficulty of the corrosion resistance of austenitic stainless steel after treatment. The key is to do it at low temperature, so as to prevent the formation of CrN and reduce the corrosion resistance of the matrix after chromium poor. Although low temperature nitriding technology solves the problem of reducing corrosion resistance of stainless steel after nitriding, ionic nitriding also has its own disadvantages, such as boundary effect, hollow cathode effect, and uneven temperature of workpiece. In order to solve the shortcomings of ion nitriding, the activated screen ion nitriding technology has been developed in the industry. Source: China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

With the continuous progress of the material processing technology, the stainless steel pipe has also ushered in a new development opportunity. Typical applications such as automobile exhaust pipe, fuel pipe, injection nozzle and other automobile components. In the production of stainless steel pipes, a flat stainless steel belt is first formed and then rolled into a circular pipe. After forming, the joint of the stainless steel pipe is required to be welded. Because the weld will affect the formability of the final parts, it is necessary to choose the suitable welding technology if the strict test standard is to be reached. Tungsten arc gas shielded arc welding, high frequency induction welding and laser welding have been widely used in the welding of stainless steel pipes. High frequency induction welding In high frequency contact welding and high frequency induction welding, the power supply equipment and the pressure supply equipment are independent. In addition, two methods can be used in the bar, is a soft magnetic element is placed in the interior of the body, which helps in the stainless steel band edge welding flow convergence. In the two case, stainless steel strip was cut and cleaned up, will be rolled up, then sent to the welding point. In addition, the cooling agent is used for cooling the induction coil used during the heating process. Then, a part of the coolant will be used in the extrusion process. In this respect, there is a great force on the pulley, which prevents the formation of porosity in the welding area. But more pressure can be used to increase the burr. So the specially designed cutters can be used to remove the burrs inside and outside the stainless steel pipe. Tungsten arc welding arc welding Traditionally, the stainless steel pipe production plant will choose tungsten electrode to protect the arc welding process. This process forms a welding arc between two non expendable tungsten electrodes. And into the inert gases from the gun guided, plasma can shield electrode, forming an ionized stream, and protect the molten weld pool. This process can effectively repeat the high quality welding process. The advantage of this process is repeated, welding process will not splash, you can also remove the porous. This is a process of electrical conduction, so the process is slow. Laser welding In all stainless steel pipe welding applications, the edge of the stainless steel band will be melted. When the clamping bracket is used to squeeze the edge of the steel pipe together, the edge of the stainless steel belt will solidify. But for laser welding, it is characterized by its high energy beam density. The laser beam not only melts the surface of the stainless steel material, but also forms a spoon hole, which leads to the very narrow appearance of the weld in the stainless steel pipe. When the power density of laser welding is less than 1MW/cm2, it will not form enough energy density to produce a spoon hole. In this way, the process obtained without a keyhole is wide and shallow. The high precision of the laser welding is higher, which reduces the grain growth and helps to improve the metallographic quality of the stainless steel. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The process of welding stainless steel pipe usually consists of three kinds of soldering, filling and cover welding. The backing welding is the most important part of the stainless steel tube welding process, which is related to the quality and progress of the project. It includes two processes: back filling argon and not argon filling. The backside argon filling protection is also pided into two kinds: solid core wire plus TIG process, solid core wire plus TIG and water soluble paper technology, while the back without argon protection is also pided into two kinds: flux cored wire backing welding, welding rod bottom welding and TIG welding. The use of stainless steel backing welding method is TIG process, according to the actual situation, can have the following four ways to do the backing welding processing, respectively by using the method of blocking back sealing plate ventilation protection; the second is only using soluble paper or combined with the method of blocking protection ventilation using soluble paper and blocking plate the use of TIG base cored wire; welding; use of flux cored wire TIG welding backing. The first is the use of the back blocking method for sealing plate ventilation protection, in prefabricated stainless steel pipe, welding need to do rotary welding, are usually easier, this method is generally used for blocking plate pipe welding on both sides of the mouth to block the ventilation protection of backing welding at the same time, the outer side of the adhesive used cloth plugging. When welding, to use the advance, lag process gas, lateral adhesive selvage welding edge tear, because the blocking plate is composed of rubber and tin, is not easy to damage, so that the welding process can ensure good weld inside filled with argon and ensure its purity, in order to effectively ensure the weld metal is not inside oxidation, ensure the quality of weld backing welding. The second is to use only soluble paper or the combination of soluble paper and plugged plate for blocking ventilation protection. Because when stainless steel pipes are fixed and welded, the inside ventilation is difficult, and some sides are easier to block. In such cases, water soluble paper and blocking plate can be used for plugging. That is to say, one side is easy to ventilate and dismantle, and the side is blocked by blocking plate, and it is not easy to ventilate. It is difficult to remove the side of the blocking plate and use water soluble paper to do the plugging. And the outer side is glued with cloth to paste the weld line for plugging. Stainless steel fixed mouth in welding, weld on both sides have not ventilation in most cases of the phenomenon, how to ensure that the inner weld argon protection is a difficult problem, in actual construction, the use of both sides of the weld of water soluble paper plugging, pass gas, from the weld center outside the use of adhesive cloth paste do plugging this method can effectively solve the above problems. When water soluble paper is used to plug and ventilate, because it is ventilated from the weld center, in the final sealing part, we need to quickly insert the vent pipe, and use the remaining argon inside to protect it, and quickly finish the bottom and seal the mouth. Using this approach, we should pay attention to water soluble paper to use double, need is stuck, or will cause water soluble paper damage loss and the inside of the weld without the protection of argon, oxidized, cause the weld cut re welding, which can not guarantee the welding quality, and has seriously affected the period. Therefore, before welding should strictly check, paste the water soluble paper. In most construction sites, this welding method is usually used to make the bottoming. Its quality can be obviously guaranteed, and at the same time, there is still a certain degree of difficulty in construction. Therefore, a careful and skilled welder is needed to do this work. The third way is not to carry out argon protection on the back, using flux cored wire plus TIG technology. This method has been used for many years in China, and the corresponding products have been used in the field welding, which has achieved relatively good economic benefits. Because the back is not filled with argon, its advantages are also very obvious, the main performance is high efficiency, convenience, low cost, suitable for installation in the construction site. However, because of its structural characteristics, the flux cored wire has high requirements for welders. The wire feeding speed is fast and the accuracy of wire feeding is also very high. It is difficult to master fully. The welders should be trained by special training and skilled. The last one is the back without argon protection, the use of flux cored wire with TIG process, in the last century in 90s, Japan’s Kobelco and other companies developed grounding wire, and all these years has been developed and applied in the grounding wire of stainless steel in the actual construction, obtained very good effect. The protection mechanism of this process is to protect the weld metal from molten slag formed by welding wire and metallurgical reaction of other alloying elements on the back weld. The frontal weld is protected by argon, slag and alloying elements. Source: China Stainless Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The corrosion resistance of duplex stainless steel and corrosion fatigue performance is outstanding, widely used in equipment made of refining and chemical industry, salt industry and other industries in the atmospheric vacuum distillation unit and catalytic cracking and hydrocracking, continuous sulfate cooking or intermittent cooking device, compressor cooler operation environment is very bad. In spite of the late appearance of this material, the development of the duplex stainless steel is very rapid. Because of its both austenitic stainless steel and ferritic stainless steel advantages in, and also make up the shortcomings of their respective, so the international attaches great importance to the development and production of duplex stainless steel, especially in the last century after 70s, with the advent of refining equipment, began production of duplex stainless steel equipment based on ultra low carbon n, the more broad road is prompted to enter the rapid development of dual phase stainless steel. Now duplex stainless steel has been combined with austenitic stainless steel, ferritic stainless steel and martensitic stainless steel as an independent large class of steel. In Europe, America and other countries, the development is very fast. But our country began developing duplex stainless steel in the middle of 70s of last century, and because of the difficulty of production of duplex stainless steel, it developed slowly in China at that time. Later, with the mass production of stainless steel used VOD furnace, AOD furnace and large vacuum induction furnace, the domestic duplex stainless steel has also developed rapidly. Below is the application field of the lower double phase stainless steel in China. In the oil refining industry, used to make the CDU duplex stainless steel, including the lining, tower components, often air cooler, cut the top of wet air cooler and cut the top after the cold water cooling tube; there is a catalytic cracking unit, including catalytic absorption desorption tower tray, pipe lining, etc., gasoline reheat; there is a hydrocracking unit, including air cooler, desulfurization reactor, water cooler heat exchange tube. In the petrochemical industry, double phase stainless steel will be used to made of polyvinyl chloride (PVC) and stripper heat exchanger; coil type oxygen chloride reactor, vinyl chloride vinyl chloride in the reboiler; methanol synthesis reactor, material / effluent heat exchanger, top condenser pressure flash tank; oxo alcohol pipe type loop reactor; acetic acid and other organic acids (formaldehyde and formic acid) production equipment and pipeline. In land and offshore oil and gas industry, duplex stainless steel is used for conveying pipes and collecting pipes, offshore oil platform heat exchangers, water treatment and water supply systems, fire fighting systems, sprinkler systems and water stabilizing systems. In the field of pulp and paper industry, the continuous sulfuric acid cooking or batch cooking device is used, or chlorine dioxide bleaching cartridge is mainly made of duplex stainless steel with excellent mechanical properties, wear resistance, corrosion fatigue and stress corrosion resistance. The dual phase stainless steel is also used in the chemical fertilizer industry, in which the urea industry, the compressor cooler pipeline. Ammonium methylamine pump body. Stripper gas pipe, condensing high-pressure condenser tube, high-pressure decomposition tower pipe and pipeline decomposition. In the phosphoric fertilizer industry, it is used to reflect the tank, slurry pump and slurry pipeline. The last use is high strength structural parts, mainly on the oil platform, such as the tensioning system of the derrick, the submarine pipeline, and the steam turbine blades, barges and so on. Source: China Duplex Stainless Steel Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

There are many factors that affect the brightness of stainless steel pipes after annealing. The main factors include the temperature, atmosphere, seal, air pressure and water vapor content in the furnace. These factors are described in detail below. The first is to look at the annealing temperature, to see if it has reached the corresponding temperature. Because the stainless steel pipe solution heat treatment is usually taken in heat treatment, annealing treatment is usually said, the best treatment is the temperature range of 1040-1120 DEG C, or the observation hole is observed in the annealing furnace that appear as incandescent state but did not appear to soften the sagging state as the most suitable annealing zone of stainless steel pipe. You can also look at the annealing atmosphere. Anneal is usually used pure hydrogen as annealing atmosphere. The purity of atmosphere is better than 99.99%. If the atmosphere is inert gas, the purity of the whole atmosphere is lower, but there must be no excess oxygen and water vapor. The third aspect is to see the sealing of the furnace body. Because the bright annealing furnace should be closed and isolated from the outside air. It uses hydrogen as a protective gas. Generally, there is only one exhaust port outside, which is used to ignite the discharged hydrogen. Check tightness can be used when the stove soap in the annealing furnace each joint, observe whether the gas leakage phenomenon; one of the most easy to run gas area is the annealing furnace inlet pipe and the outlet seal, this part of the very easy to wear in the long-term use, often need to check if there is a problem immediately change. The fourth aspect is to protect the gas pressure in the furnace. In order to avoid the micro leakage, the furnace should ensure that the gas should always maintain a certain positive pressure. If it is a hydrogen protective gas, it usually requires 20kBar above. The last major factor is the content of water vapor in the furnace. On the one hand to check the furnace material is not dry, in the first furnace, furnace material must be rapid drying; second is to check into the furnace of stainless steel pipe is left too much water, especially if there is a hole on the pipe, you will not be able to Water Leakage in, otherwise it will completely destroy the furnace atmosphere. If these are done in the comparison, in the normal annealing process, blow back 20 meters of stainless steel pipe will start to glow and glare. Source: China Stainless Steel Pipess Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the process of demolition of old buildings, the removal of stainless steel pipeline is an area requiring special attention. This article mainly talks about the construction methods under the demolition of stainless steel pipelines. When removing the old pipelineline of stainless steel pipelineline, most of them first use plasma cutting machine to cut the pipelineline, then remove the pipeline by hand. If the caliber of stainless steel pipeline is larger than DN200, you can also use hand hoist to help lift and unload. The disassembled pipelines need to be cleaned out in time so that the new pipelines can be prefabricated. When the new stainless steel pipelineline is prefabricated, the pipelineline can be lined up on the ground according to the original pipelineline. During the prefabrication period, the location should be based on the actual situation of the site. Before that, we need to see the qualification certificate, chemical composition and mechanical properties of the stainless steel pipeline and fittings manufactured by the company. We also conduct heat treatment and intergranular corrosion tests for pipelines. Also check the appearance of the pipeline to ensure that there are no cracks and heavy skin defects on the surface of the stainless steel tube. It is usually cleaned before the pipeline is installed to remove oil and other dirt. Prohibited the use of oxygen acetylene cutting of stainless steel pipeline, and should use the saw, hand saw, grinding wheel cutting machine, plasma cutting machine, pipeline cutting, grinding wheel with special grinding wheel. Attention should also be paid to the use of welded joints and fittings for 18-8 stainless steel pipelines, because the 18-8 stainless steel belongs to austenitic stainless steel, so the suitable way of welding is manual argon arc welding. Stainless steel pipelines need to be installed after the support is fixed, and the pipelines can not directly contact with the carbon steel support. Instead, stainless steel sheets, chloride free plastic sheets and rubber plates should be inserted between pipelines and supports. According to the difference between the conveying medium and the operation temperature, the flange gaskets shall be selected according to the specifications, and the contents of chloride ions in the non-metallic gaskets can not be greater than 50*10-6. When the pipelineline of stainless steel pipeline is long or the temperature of the conveying medium is high, the compensator should be added to the pipelineline. Finally, after the installation of the pipelineline, the test pressure test should be done according to the design or specification requirements. In water pressure test, the content of chlorine ion in water should not be higher than 25*10-6. Source: China Stainless Steel Pipelines Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel welded pipe is also called pipe, most of which is a stainless steel tube which is made of stainless steel tape after curling the equipment. Its production and processing technology is simple and efficient, the specifications are varied and the investment is low, but the strength of the product is generally lower than that of the seamless steel pipe. With the continuous progress of production technology of high-quality stainless steel strip rolling and rapid development of welding technology, welding quality is more and more high, varieties and specifications of welded steel pipe is also increasingly perse, and in more and more fields especially in the heat exchanger tube, decorative tube, etc. in the low-pressure fluid pipe effectively replacing seamless steel prices more expensive. There are two characteristics of stainless steel welded pipe, one is the small diameter stainless steel welded pipe is continuous online production, the thicker the wall is, the higher the investment of the unit and the melting equipment, the lower its economic and practical. The thinner the tube wall is, the lower the input output ratio will be, and the technology of the product will also decide its characteristics. The accuracy of the ordinary welded steel pipe is higher, the wall thickness is even, the brightness inside the tube is also high, and it can be arbitrarily fixed. So it shows its good economy and beauty in the field of high precision, medium and low pressure fluid application. The welding characteristics of this kind of welded pipe can be pided into two kinds according to the welding process: automatic welding and manual welding. Automatic welding is usually used by submerged arc welding and plasma welding, and manual welding is usually used for argon arc welding. There are many ways to pide the stainless steel welded pipe. According to the weld style, straight welded pipe and spiral welded pipe can be pided into common welded pipe, heat exchanger tube, condenser tube, galvanized welded pipe and so on. And the weight calculation formula of stainless steel welded pipe is (outer diameter – wall thickness) x wall thickness x0.02491x length = weight (kg) The strength of the spiral welded pipe in the stainless steel welded pipe is usually higher than that in the longitudinal welded pipe. Generally, the welded pipe with smaller diameter is welded by straight seam, while the large diameter welded pipe is mostly welded by screw. Add a little knowledge, because stainless steel welded pipe is mainly made of stainless steel band, so in general cases, welded pipe is not comparable to seamless steel pipe in people’s eyes. Source: China Stainless Steel Welded Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When fastening parts are used, the stainless steel fasteners will sometimes be locked. However, if the carbon steel fasteners are used, the locking is seldom seen. An important reason is that the stainless steel is soft and the carbon steel fasteners are relatively stiff. Stainless steel materials have good ductility, but there are some differences between hardness and carbon steel. Is there any other reason for that? In fact, it is because the stainless steel material has good corrosion and corrosion resistance. When its surface is damaged, a thin and dense chromium oxide layer will form on the surface to prevent corrosion from developing to a deeper level. When the stainless steel fastener is locked, the pressure and heat between the teeth will destroy and wipe out the chromium oxide layer on the surface of the material, resulting in the direct blocking or shearing of the teeth and forming adhesion. When the sticky situation persists, the stainless steel fastener will be locked directly and completely, and it can no longer be unloaded or locked. This series of continuous movements of blocking, shear, adhesion, and lock death can be done in a very short few seconds. Avoid the stainless steel fasteners have locked the best properties of stainless steel products first and follow the correct operation of the corresponding procedures so I want to. About 304 or 316 stainless steel like materials have good ductility and viscosity, it can be clearly seen in the turning process, such as the 304/316 bar in the car when processing chip it is folded extrusion, and other materials such as brass or iron in the turning process for Clastic debris removal shaped or filamentous. If the use of electric tools in or out when the stainless steel screws and nuts under high torque when the thread contact begins to heat, a point of contact adhesion so as to bring up a large, then the internal thread and external thread bonding formed together locked at the bolt group is scrapped, and even may be installed so that the whole work have become bad. The effective way to reduce or avoid the locking of stainless steel screws is the corresponding method in the process of installation and application. The protection of thread is controlled in semi-finished products, rubbing teeth and finished product transportation packages. No matter whether users use electric tools or overload torque or stainless steel screws and nylon lock nuts, they will not lock. They are exactly the same as carbon steel fasteners. This can reduce the loss to the lowest or even completely without changing the installation tools and installation methods in the process of use. In fact, the cost of this kind of stainless steel screw anti lock solution is controllable and cheap, it will only increase a small amount of extra cost or even optimize, and no additional cost will be needed. Source: China Stainless Steel Fasteners Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

As the demand for stainless steel materials is more and more widely used, stainless steel welded pipes, as one of the applied varieties, are also widely used in various industries. As the stainless steel industry welded pipe, because of the different surface treatment, there are two kinds of welded pipe and polished pipe. Below are the principles and advantages and disadvantages of the two kinds of welded pipes. The welded pipe with welding seam is welded by automatic welding, one side welding is formed on double side, and the weld on the pipe is smooth and smooth. Because the pickling pipe is made from the first grade stainless steel plate, the surface of the stainless steel welded pipe is consistent with the surface of the original plate. Polishing by hand welding pipe is formed by molding, polishing processing, surface passivation layer and cast weld pipe, stainless steel pipe surface showed a higher degree of brightness. Below, look at the contrast between the stainless steel belt welded pipe and the polished pipe. First, the wall thickness of the welded pipe with welding seam is more uniform and has higher bearing pressure. The wall thickness of the raw material will be thinner, especially in the weld area, by artificial polishing. The thinner the thickness of the weld wall, the smaller the bearing capacity of the weld. Secondly, the welded pipe with weld seam pickling ensures the performance of austenitic stainless steel. Most stainless steel welded pipes are austenitic stainless steel used as raw materials, such as 201, 202, 304, 316L stainless steel and so on, while austenitic stainless steel is non-magnetic or weak magnetic. The chemical composition fluctuates after polishing, which makes the austenitic stainless steel magnetic. The third is high corrosion resistance of welded pipe with seam pickling. The polishing pipe eliminates the passivation layer generated after pickling of raw materials, which results in the rusting of the welded pipe in normal environment, thus weakening the corrosion resistance of the stainless steel pipe. In addition, the quality stability of the welded pipe with weld seam pickling is better. The polished welded pipe is a product popularized from the Wenzhou area. But because most of the Wenzhou area of stainless steel pipe used raw material is two grade materials or recycled material, to cover up the two grade stainless steel material surface spray, heavy leather and corrosion point must be polished; even some in order to reduce the cost of materials, full use of waste recycling in a pipe joint, a plurality of transverse seam. This kind of polished pipe is not guaranteed on the quality of the raw material, and the quality of the pipe itself is more difficult to ensure. The last point is that the practicability of the welded pipe with weld seam pickling is better. In terms of industrial welded pipe, stainless steel welded pipe is mainly used for its own mechanical properties, corrosion resistance and channel performance. For stainless steel welded pipe, its surface gloss is relatively low, which, of course, besides decorative pipe and sanitary welded pipe. Therefore, the industrial welded pipe is not necessary to use the high cost but not the performance of the polished welded pipe. Source: China Stainless Steel Welded Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)