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TIG welding (Tungsten Inert Gas arc Welding), also known as tungsten inert gas welding. TIG welding is also used for thicker sections root pass welding, the main welds surfacing. The heat source is a DC TIG welding arc, the working voltage of 10 to 15 volts, but the current up to 300 A, the workpiece as the positive electrode, the tungsten electrode welding torch as the cathode. The inert gas is usually argon. The process of TIG welding: Inert gas fed through the torch, the arc weld pool on the sides and form a shield. To increase the heat input, generally within the argon with 5% hydrogen. However, in the ferritic stainless steel welding, argon within not hydrogenated. Gas consumption per minute, about 8 to 10 liters. In the welding process, in addition to inert gas is blown from the welding torch, the best protection is also blown into the weld seam from the back with a gas. Classification TIG manual welding pided by mode of operation, semi-automatic and automatic welding categories. GTAW, the torch movement and adding filler wire entirely by hand operation; semi-automatic TIG welding, torch movement by manual operation, but the filler wire by wire feeder automatic feeding; Automatic TIG arc welding, such as workpiece stationary arcing motion, then the welding torch mounted on a small car, the car or walking and filler wire can be used cold or hot filament yarn way to add. Hot wire means increasing deposition rate. Some occasions, such as sheet metal welding or weld backing, sometimes without adding filler wire. The three welding methods, GTAW most widely used, semi-automatic TIG welding is rarely used.

Concentric reducer is the corrosion resistance of steel. Concentric reducer corrosion resistance depends on the steel alloying elements. It contains chromium stainless steel stamping elbow is get the corrosion resistance of the basic elements, while about 1.2% chromium content in steel, chromium and oxygen effect of corrosive medium, in the steel surface to form a thin layer of oxide film (since the passivation film), but to prevent further corrosion of steel substrate. In addition to the chromium, the commonly used alloying elements and nickel, molybdenum, titanium, niobium, copper, nitrogen, etc, in order to meet the various USES of concentric reducer organization and performance requirements. Concentric reducer must be adopted in production of production and processing technology, guaranteed to show a good role in production and processing, and performance. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Welded pipe is made by forming flat products (strip, sheet or plate) into the desired shape, in this case, normally round. Once the desired shape has been achieved, a high energy source is used to melt the metal locally at the weld joint. It is squeezed together and allowed to solidify, forming a weld bead. The high energy source may be an electric arc, a plasma arc, a laser beam, or even an electron beam.  The as-welded weld bead is typically somewhat thicker than the adjacent base metal and needs to be modified to match the base metal thickness, and to correct the undesirable physical, chemical and corrosion resistance attributes of the weld. Welded pipe manufacturing At the start of the welded pipe manufacturing process so called slabs or billets are cast in a steel mill. Dependent on the external dimensions and wall thickness there are different methods of producing welded pipes and pipes: Electric Resistance Welding (ERW), Fusion Welding (EFW) and Double Submerged Arc Welding (DSAW). In the ERW and EFW manufacturing process welded pipes are formed by hot or cold rolling plate and welding the seam. In order to keep the outside (O.D.) surface of a welded pipe smooth and uniform a cutting tool called scarfing blade is used to remove the weld flash. Scarfing from the inside (I.D.) welded flash is also possible. With a heat treating at the end of the manufacturing process the weld zone of the steel pipe can be made less visible. Due to the weld seam lower operating pressures are stated in accordance with ASME compared to seamless pipes. In general welded pipes possess tighter dimensional tolerances than seamless pipes and are less costly if produced in same quantities. ERW pipe manufacturing A process for producing welded pipes is Electric Resistance Welding (ERW) also known as Contact Welding. The manufacturing starts by cold-forming a coiled plate of steel with eligible thickness and certain width into a cylindrical shape. As the cylindrical plates come together, an electric current using heat merges the edges together to create the final product. EFW pipe manufacturing Processing of Electric Fusion Welding, also called Continuous Welding begins as coiled steel with appropriate thickness, width and weight is made. To form a continuous ribbon of steel several coils are welded together. Then the steel ribbon is heated to the necessary temperature and formed into an oval. In the next step the edges of the pipe strip are permanently pressed together by rolls in order to receive a forged weld. In the last stage sizing rolls convert the welded pipe into specific dimensions. DSAW pipe manufacturing The process of producing Double Submerged Arc Welded Pipes first contains forming steel plates into cylindrical shapes. Later on the edges of the rolled plate are forged so that v-shaped notches are on the exterior and interior area of the seam. Then the pipe seam is being welded by an arc welder submerged under flux. Welded pipe sizes and dimensions Welded pipes are used especially for pipeline constructions and for larger dimensions in the process plants; any specifications and qualities are part of our supply program. For example, we supply carbon steel pipes for pipeline projects throughout the world according to: API 5L X 52, X60, X65, X70 Welded carbon and alloyed process plant pipes in acc. to below standards: ASTM A333, 671, 672, 691 Welded Stainless steel, special alloys pipes for chemical and petrochemical plants to: ASTM A 312, 358, 778, 928, ASTM B 619, B725 All materials are also available in acc. to equivalent DIN/ EN standards and grades. Some manufacturers will simply remove the excess material of the weld bead by scarfing the inside portion and either grinding or scarfing the outside portion.  This method of weld bead modification only changes the physical dimension and leaves the undesirable as-welded physical, chemical and corrosion resistance properties as they were. To properly modify this condition the weld bead is cold worked locally and is given a solution anneal heat treatment.  This results in a microstructure that exhibits the same physical, chemical, mechanical, and corrosion resistance properties as the base metal. The wall thickness advantage of comparison between welded pipe and seamless pipe Welded pipe, being made from flat rolled strip material exhibits extremely consistent wall thickness. A 2.11mm nominal wall pipe typically shows actual variation of 0.07 mm or less at a point. The variation from production lot to production lot is typically 0.1 mm or less. The dimensional flaw of welded pipe may be its ovality, or roundness. Seamless pipe has a very round and very consistent diameter as a result of being extruded through a die, with typical measured variations in diameter of +/- 0.025mm for a 25 mm OD size. Roll formed welded pipe on the other hand, typically varies about +/- 0.050 mm to +/- 0.075 mm for the same nominal OD. However, for most applications, good concentricity is more valuable than good ovality. Ovality can be corrected or compensated for during fabrication or installation. A non-concentric (or eccentric) condition cannot. What are the criteria that should be considered? Specifying a manufacturing process rather than specifying measurable results in any product is always a slippery slope.  The type of results and the value of measureable results need to be performance-based and to consider application critical attributes. If working pressure is of concern, then a minimum tensile or yield strength or burst pressure value should be considered, along with dimensional attributes like wall thickness and concentricity. Wall thickness and concentricity should also be of concern when heat transfer rates are an issue. pipes that exhibit a non-concentric or eccentric geometry may develop hot spots or weak spots at thin or thick sections around the circumference, as well as along the length. This could significantly affect process parameters in a heat exchanger. If working temperature, either elevated or cryogenic, is of concern, test methods and data representative of the field conditions should be considered.  Basically, if material selection is properly executed, the product form should be insignificant. What is the advantage of seamless over welded? When welded pipe is properly manufactured by a reputable supplier, seamless does not have any advantage over welded. Which is more cost-effective? Why? From a pipe manufacturing standpoint, typically welded is more cost-effective as a result of the minimised labour input and reduced manufacturing scrap. From a fabrication standpoint, welded is more cost effective because of the reduced number of field orbital welds needed to join inpidual lengths of pipe together to create the umbilical. Seamless pipes are typically available in fixed finite lengths such as 6 or 12 metres. Welded pipe on the other hand is available in continuous lengths up to 25,000 metres. A single continuous pipe from a coil of strip material is typically about 500 metres long. A splice weld is made on the strip material at these 500 metre intervals and is cold worked before roll forming the pipe. It is then solution anneal heat treated and X-ray examined. The net result is that strip material is infinitely long and the final length of the pipe is then limited only by the size of the spool on which it can be coiled and the associated material shipping and handling capabilities. Because these splice (orbital) welds are made and processed at the factory in a controlled environment the potential for corrosion is significantly reduced as compared to the field orbital welds which cannot be cold worked and are typically not heat treated.  The microstructure and the physical, chemical and corrosion resistance properties of the factory welds are virtually identical to those of the base metal. When purchased from a reputable reliable supplier, welded pipe can offer advantages of economy without sacrifice of performance. The economy is realised in both initial purchase costs and in time and labour in fabrication / installation. Coiled welded pipe can be supplied with a splice (orbital) weld that has been cold worked and solution annealed at intervals of about 500 metres. The maximum distance between splice welds in coiled seamless pipes is typically about 30 metres.  The wall thickness dimension control of welded pipe is superior to that of seamless pipe. Welded pipe is acceptable as per most pressure vessel codes, and with additional non-destructive examination it can be used in place of seamless for lethal service applications. With the rapid development of high-quality strip rolling production and progress of welding and testing technology, and constantly improve the weld quality, varieties and specifications of stainless steel welded pipe is increasing, and in more and more fields especially in the heat exchanger pipe, oil pipeline and other aspects instead of the seamless steel pipe.

Industrial stainless steel pipe fittings refers to the connection of two parts of the pipeline or other pipe fittings items, is an important industrial pipe fittings, including tee, cross, elbow, reducer, head, flange, belonging to the fabricated metal products industry . Many types of industrial metal fittings, according to different standards can be pided into different types. According to the current stage of China’sstainless steel pipe fittings manufacturing enterprises of the product classification standards, according to its function will be pided into industrial stainless steel pipe fittings: stainless steel elbow, stainless steel flange, stainless steel tee, stainless steel cross and stainless steel reducer. Table 1: Classification of industrial stainless steel pipe fittings Type The main content Stainless steel elbow Used for turning the pipe Stainless steel flange A part for interconnecting the pipe and the pipe is connected to the pipe end Stainless steel tee For the three pipes where the collection Stainless steel cross For the four pipes where the collection Stainless steel reducer For the different diameter pipe connected to the two places Industrial stainless steel pipe fittings are mainly used in petroleum, petrochemical, chemical, natural gas, shipbuilding, electric power, medicine, gas, heat and other industries, especially in the industry, especially in the industrial, industrial, industrial pipe fittings products with strong special features, high added value and wide application characteristics. Rock gas, marine engineering and nuclear power and other emerging areas of great space, the prospects should be optimistic. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Wrought steel pipe is cheaper than wrought iron pipe and consequently is used more widely in heating, ventilating, and air-conditioning than the latter. Depending on the method of manufacture, wrought-steel pipe is available as either welded pipe or seamless pipe.Seamless wrought-steel pipe finds frequent application in high-pressure work. The wall thickness and weights of wrought-steel pipe are approximately the same as those for wrought-iron pipe. As with wrought-iron pipe, the two most commonly used weights are standardand extra strong. Welded wrought steel pipe The welded wrought steel pipe manufacturing involves moving steel strips through rollers that form the material into a tubular shape. These strips then pass through a welding device that fuses them into a single pipe. Seamless wrought steel pipe Seamless wrought steel pipe starts as a solid piece of heated steel. Forced through a form that shapes the material into a hollow tube, the pipe is then machined into appropriate dimensions.

A tube sheet is a plate, sheet, or bulkhead which is perforated with a pattern of holes designed to accept pipes or tubes. These sheets are used to support and isolate tubes in heat exchangers and boilers or to support filter elements. Depending on the application, a tube sheet may be made of various metals or of resin composites or plastic. A sheet tube may be covered in a cladding material which serves as a corrosion barrier and insulator and may also be fitted with a galvanic anode. Tube sheets may be used in pairs in heat exchange applications or singularly when supporting elements in a filter. Perhaps the best known use of tube sheets are as supporting elements in heat exchangers and boilers. These devices consist of a dense arrangement of thin walled tubes situated inside an enclosed, tubular shell. Tubes are supported on either end by sheets which are drilled in a predetermined pattern to allow the tube ends to pass through the sheet. The ends of the tubes which penetrate the tube sheet are expanded to lock them in place and form a seal. The tube hole pattern or “pitch” varies the distance from one tube to the other and angle of the tubes relative to each other and to the direction of flow. This allows the manipulation of fluid velocities and pressure drop, and provides the maximum amount of turbulance and tube surface contact for effective Heat Transfer. In cases where it is critical to avoid fluid intermixing, a double tube sheet can be provided. The design of tube sheets is a fairly precise and complex process; the exact number of tubes needs to be established and a pattern of holes calculated to spreads them evenly over the tube sheet surface. Large exchangers may have several thousand tubes running through them arranged into precisely calculated groups or bundles. Sheet design and production is largely automated these days with computer software (like CAD) performing the calculations and the tube sheet drilling done on computer numerical control (CNC) machines. In this design, the outer tube sheet is outside the shell circuit, virtually eliminating the chance of fluid intermixing. The inner tube sheet is vented to atmosphere so any fluid leak is easily detected.

China’s industrial metal pipe fittings industry, enterprises, small scale, relatively scattered production situation. As of the end of 2013, China has a total of more than 40,000 industrial metal pipe fittings business, small-scale enterprises, the majority of private enterprises, the annual production capacity of 1,000 tons in general; annual sales of more than 20 million yuan of about 200 enterprises. 2007-2013, China’s metal pipe production showed a year-on-year trend, but since 2011, growth has declined. Industrial metal pipe products mainly supply petrochemical, natural gas, ship, electricity, heat, medicine and other industries. With the national efforts to strengthen energy investment, the discovery of a large number of new oil fields and the strategy of West-East Gas Transmission, the “gasification strategy” of various provinces and cities in the country, deep processing of coal resources, strategic reserves and more use of aviation fuel will be greatly enhanced Pipe fittings industry’s sustainable development. The main raw material of industrial metal pipe is steel products, including carbon steel and stainless steel and other materials, the industry’s upstream industry is steel ingot, steel pipe, steel manufacturing. With the development of materials technology, titanium-based alloys, nickel-based alloys and other new materials are also beginning to apply a large number of pipe fittings industry. The price, variety and quality of iron and steel products have an important influence on the industrial metal pipe fittings industry. China is a large steel producer, steel pipe, steel, ingot products sufficient supply of raw materials to ensure that the industry supply. But in recent years, with the rising prices of iron ore, steel prices continue to rise, reducing the domestic industrial metal pipe industry profits. The industrial chain of industrial metal pipe industry Industrial metal pipe industry is widely used in various fields, including petrochemical, shipbuilding, electric power, natural gas, medicine, food and many other industries. In the 12th Five-Year Plan, the State Council proposed to speed up the development of new energy sources, promote the clean and efficient use of traditional energy sources, actively develop hydropower under the premise of ecological protection, develop nuclear power on the basis of ensuring safety, strengthen power grid construction, Improve the oil and gas transmission pipeline network, expand oil and gas strategic reserves. Downstream energy, power industry development requires a lot of equipment investment, and equipment manufacturing performance, specifications, materials of different industrial metal pipe products. Downstream enterprises and industrial metal pipe fittings enterprises to establish long-term stable cooperative relations to ensure the safe operation of equipment and adequate supply. The development of the downstream industry to ensure that the industrial metal pipe industry has a stable and growing market demand. The domestic industrial metal pipe fittings industry, the general market competition, such as ordinary carbon steel, small-caliber varieties of products such as adequate supply, but the large diameter, composite materials, high-performance (high temperature, low temperature resistance, high pressure, corrosion) and for special industries Demand for the development of new products in short supply. Oil and gas industry needs to build long-distance pipeline large diameter, high pressure pipe, oil cracking industry in urgent need of high temperature, high pressure collection of pipe fittings, chemical industry required for the production of stainless steel metal matrix composite pipe fittings, power industry required Can withstand supercritical or even ultra-supercritical working state of the alloy, thick-walled pipe, chemical, shipbuilding industry, the need for standardized pipe system modules are in short supply range of products. Mainly due to cost factors, developed countries, the production of metal pipe less, need from China, India, Brazil, China Taiwan and other countries and regions, the Chinese metal pipe export market in the future have greater room for growth. In recent years, thanks to the huge demand of the downstream industry, industrial metal pipe industry, the overall market demand for rapid growth, the market supply is also increasing rapidly. In the course of exploiting the downstream customer market, the major enterprises in the industrial metal pipe fittings industry rely on their unique advantages in customer resources to form a concentrated market in different directions, mainly in the petrochemical, shipbuilding, power and other industries. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

What is a barred tee? A barred tee (pigged tee) is a tee or any fitting with a branch used in pipelines that is pigged and has a restriction bar welded internally preventing the pig from traveling down a branch connection. The bars are installed so they are flush with the inside diameter of the pipeline to keep the pig from hanging up when it passes through. The bars should be of a similar or identical material as the parent material. Bars are placed on the internal side of a tee or really any branch connection big enough to sidetrack a pig while traveling down a pipeline. The size of the bars on the tee should be small enough so that they do not restrict the flow from the branch connection.  However, they should be large enough to prevent breakage based on the flow rate through the branch connection of the tee. Barred tees are pipe fittings with two outlets, one at 90 ° to the connection to the main line that has tiny holes. Barred tees can either be extruded or fabricated and are used to connect two pieces of pipe or fittings. Barred tees are used in pipelines that are pigged. The specificaition of Barred Tee (Pigged Tee) Material: Carbon steel, Alloy steel, Stainless steel, etc Size: Dn100- DN1200 Specification: Sch20- Sch 160 . Standard: ASME/ANSI B16.9. Coating: Black painted, varnish oil. Packing: Wooden case, pallet. How to design and produce the barred tee (Pigged Tee)? The shape of a Barred tee (Pigged Tee) is like a butt welding pipe tee with some bars in the branch of the tee. The bars are used for preventing the pig from running out in the branch of the main pipe. It is commonly used in a pigged pipeline, so it is also called pigged tee. The bars in the branch should be installed flush with the inside diameter of main pipe. Commonly the bars are welded with the tees. It really depends on the kind of pig you are running. A mandral pig will never make the turn into any size branch. A foam pig will pretty much go through whatever pipe has the lower pressure (I once had a 10-inch uncoated foam pig go through a 2-inch weld-o-let on a receiver barrel, but it took a while and did not remain intact). Realistically, I always bar tees since most company standards only allow reducing tees to be used down to 1/2 the run diameter (i.e., I can use a 10X6 tee, but not a 10X4 if I could buy one). 1/2 the diameter can take a coated foam pig and some turbo pigs. We use foam pigs and nerf ball type pig all the time in my area, we use barred tees down to half the diameter of the main line.

Superior structural characteristics of spiral steel pipe determines its power, chemical, petroleum and nuclear industry and other fields increasingly widely used.  Spiral steel pipe technology in the heat, mix in many fields such as chemical is widely used to obtain good results. But the spiral technique in mass separation of the application up to now is still relatively small. In recent years, many people will spiral technology used in microfiltration, nanofiltration, osmotic membrane distillation and mass transfer of hollow fiber membrane separation process, have achieved good results. This is because the coil may be formed inside the pipe perpendicular to the axial direction of the tube of the secondary flow, which secondary flow and axial spiral mainstream combined into forward movement of such mass transfer layer of the fluid, which not only depend on the fluid The radial diffusion, as well as the role of the secondary flow radially, is equivalent to the boundary layer destruction, mass transfer surface profile. Enhances the movement of fluid in laminar flow mixing to enhance mass transfer. Spiral will also improve the outflow tube type, ie a flow-type shell. Increasing radial mixing liquid tube, shell reduce channeling and dead zone, and due to the proximity crossflow, the surface of the fiber mass constantly updated, the shell side mass transfer coefficient is further increased. Spiral universal superiority lies in this. But it is in many other aspects of the practical application of the special role.

The surface treatment technology of stainless steel Stainless steel has a unique strength, high wear resistance, excellent corrosion resistance and rust and other excellent features. It is widely used in chemical industry, food machinery, electrical and mechanical industry, environmental industry, household appliances and home decorating industry, finishing industry, giving people a beautiful and noble feeling. Prospects for the development of stainless steel will be more widely applied, but the development of application of stainless steel surface treatment largely determine its level of technological development. A stainless steel surface treatment methods commonly used varieties 1.1 Introduction 1.1.1 stainless steel main components: general contain chromium (Cr), Nickel (Ni), molybdenum (Mo), titanium (Ti) and other high-quality metals. 1.1.2 Common steel: stainless steel with chromium, including Cr ≥ 12% or more; nickel-chromium stainless steel with Cr ≥ 18%, with Ni ≥ 12%. 1.1.3 Microstructure of structure from stainless steel: a austenitic stainless steel, for example: 1Cr18Ni9Ti, 1Cr18Ni11Nb, Cr18Mn8Ni5. Martensitic stainless steel, for example: Cr17, Cr28 and so on. Commonly referred to as non-magnetic stainless steel and with a magnetic stainless steel. 1.2 Common stainless steel surface treatment methods commonly used stainless steel surface treatment technology has the following approach: ① surface color bleaching treatment; ② mirror-bright surface treatment; ③ surface shading. 1.2.1 Surface color bleaching treatment: stainless steel in the process, after the coil, bar-side, welding or heat treatment after the artificial surface of the roast, producing a black oxide. This hard gray-black oxide is mainly NiCr2O4 and NiF two kinds EO4 components, before the general use of hydrofluoric acid and nitric acid to remove corrosion strong. However, the cost of this approach large, polluting the environment, harmful, corrosive larger, gradually be eliminated. Oxide present there are two treatment methods: ⑴ sandblasting (pill) method: The main jet is the use of micro-glass beads method, remove the black oxide surface. ⑵ chemical method: the use of a non-polluting pickling and passivation paste at room temperature with a non-toxic inorganic additives, cleaning fluid immersion. Qualities of stainless steel so as to achieve the purpose of whitening. Basically looks after the deal is a light color. This method for large, complex products are more applicable. 1.2.2 mirror-bright stainless steel surface treatment: stainless steel products according to user requirements and the complexity of the situation is different, respectively mechanical polishing, chemical polishing, electrochemical polishing and other methods to achieve the glossy shine. Advantages and disadvantages of these three methods are as follows: 1.2.3 Surface shading: stainless steel stainless steel color not only gives a variety of colors, increase product varieties and improve product wear and corrosion resistance. There are several methods of stainless steel color: ⑴ chemical oxidation coloring method; ⑵ electrochemical oxidation coloring method; ⑶ coloring oxide ion deposition method; ⑷ high-temperature oxidation coloring method; ⑸ gas cracker coloring. A brief overview of various methods are as follows: ⑴ chemical oxidation coloring: that a particular solution, formed by chemical oxidation of the color film, there dichromate method, mixed sodium method, curing method, acid oxidation and alkaline oxidation . General “Yin Division Act” (INCO) use more, but a number of products in order to ensure consistent color, must be controlled with the reference electrode. ⑵ electrochemical coloring method: in a specific solution, formed by electrochemical oxidation of the color film. ⑶ ion deposition oxide coloring chemical method: the workpiece is placed in a stainless steel vacuum coating machine by vacuum evaporation coating. For example: titanium gold watch cases, watch band, usually gold. This method is suitable for high-volume processing. Because the large investment, high cost, low-volume products uneconomical. ⑷ oxidation coloring: in particular molten salt, the immersion of the workpiece to maintain a certain process parameters, so that the workpiece to form a certain thickness of oxide film, while showing a different color. ⑸ gas cracking shading: more complex, seldom used in industry. 1.3 selection of stainless steel surface treatment method of choice which, according to product structure, material, and different requirements on the surface, use the appropriate method of treatment. 2. stainless steel parts from corrosion of the common causes of corrosion 2.1.1 2.1 Surface chemical contamination: attached to the surface of the oil, dust and acid, alkali and salt corrosion under certain conditions, into the medium, and stainless steel parts in some of the chemical composition reaction, chemical corrosion and rust. 2.1.2 scratch the surface: a variety of scratch damage of the passive film, the lower stainless steel protection, easy to react with the chemical mediators, chemical corrosion and rust. 2.1.3 Cleaning: Cleaning is not clean after pickling passivation caused by residue retention, direct corrosion stainless steel parts (chemical attack). Electrochemical corrosion of carbon steel contamination 2.2 2.2.1: carbon steel with scratch and corrosion caused by exposure to medium to form the original cells resulting electrochemical corrosion. 2.2.2 Cutting: cutting slag, splatter and other material attached to rust and corrosion medium to form the original cells generated electrochemical corrosion. 2.2.3 grilled School: flame heating the composition and microstructure of the regional changes and uneven, and the corrosive medium to form the original cells arising from electrochemical corrosion. 2.2.4 Welding: welding area of ​​physical defects (undercuts, pores, cracks, lack of fusion, incomplete penetration, etc.) and chemical defects (coarse grains, grain boundary chromium depletion, segregation, etc.) and corrosive medium to form the original cells and produce electrochemical corrosion. 2.2.5 Material: stainless steel chemical defects (non-uniform composition, S, P impurities, etc.) and physical surface defects (loose, sand holes, cracks, etc.) will help with the corrosive medium to form the original cells arising from electrochemical corrosion. 2.2.6 Passivation: stainless steel pickling passivation effect is caused by poor or uneven surface passive film is thin, easy to form the electrochemical corrosion. 2.2.7 Cleaning: retention of stainless steel pickling passivation chemical residue and the resultant corrosion of stainless steel parts with the formation of electrochemical corrosion. 2.3 The stress concentration caused by stress corrosion easy to short, stainless steel due to its special microstructure and surface passivation film, making it more difficult under normal circumstances, a chemical reaction with the media corrosion, but not in any condition not to be corrosion. In corrosive media and incentives (such as scratches, splashes, cutting slag, etc.) under the conditions of existence, corrosive stainless steel can occur with slow chemical and electrochemical corrosion reactions and corrosion under certain conditions, very fast and produce corrosion phenomena, in particular, pitting and crevice corrosion. The corrosion mechanism of stainless steel parts are mainly electrochemical corrosion. Thus, in the process of stainless steel products in the processing operations should take all effective measures to prevent corrosion conditions and incentives for production. In fact, many corrosion conditions and incentives (such as scratches, splashes, cutting slag, etc.) for the appearance of the product quality has a significant adverse impact, it should and must be overcome. 3. Stainless steel products processing problems 3.1 defects in welds: weld defect is more serious, the use of hand-processing methods to compensate for mechanical polishing to produce the grinding marks, resulting in uneven surface and affect appearance. 3.2 Surface inconsistent: only weld pickling passivation, but also result in uneven surface and affect appearance. Difficult to remove scratches. 3.3: Overall pickling passivation, nor can the processing for a variety of scratches removed, and can not be removed as scratches, weld splatter and adhere to the stainless steel surface, splash, etc. impurities, resulting in corrosive media under the conditions of the existence of a chemical or electrochemical corrosion and rust corrosion. 3.4 Passivation polishing uneven: hand-polished after pickling passivation of the larger piece, it is difficult to achieve uniform treatment effect, can not get the desired uniform surface. And work expenses, supplies and higher costs. 3.5 pickling capacity is limited: pickling and passivation paste is not a panacea for plasma cutting, flame cutting and production, and black oxide, is more difficult to remove. 3.6 scratches caused by human factors more serious: the lifting, transport and structural processing, bump, drag, hammering scratches caused by human factors such as more serious, making the surface more difficult, but also dealing with the resulting corrosion the main reason. 3.7 Equipment factors: the profile, plate roll bending, bending process, resulting in scratches and creases are also the main reason for rust treatment. 3.8 Other factors: the stainless steel raw materials in the procurement, storage process, due to lifting, transport processes of the bump and scratch but also more serious, is one of the causes rust. 4. Should take preventive measures 4.1 storage, lifting, transportation 4.1.1 stainless steel parts store: there should be special storage racks, storage racks should be wood or steel frame painted surface with rubber mats or pads, in line with carbon steel and other metal materials isolation. Storage, the storage location should be easy lifting, and other materials storage area is relatively isolated, there should be safeguards to prevent dust, oil, rust on stainless steel contamination. 4.1.2 Stainless steel lifting components: lifting, should be dedicated spreader, such as lifting belts, special chucks, etc., prohibited the use of steel wire rope so as not to scratch the surface; and in the lifting and placement should avoid scratches caused by the impact of the bump. 4.1.3 Stainless steel pieces of transportation: transportation, transportation applications (such as car, car batteries, etc.), and isolation precautions have to be clean to prevent dirt, oil, pollution, rust stainless steel. Non-drag, to avoid the bump, scratch. 4.2 Processing 4.2.1 Processing Zones: Stainless steel parts processing area should be relatively fixed. Stainless steel parts processing zone isolation measures should be taken to the platform, such as covered with rubber mats. Stainless steel parts processing zones set management, civilized production should be strengthened to avoid damage to the stainless steel parts and pollution. 4.2.2 Cutting: Cutting stainless steel parts using cutting or plasma cutting, sawing, etc. ⑴ cut: cut, the stent should be sent to isolation, drop hopper should be paved with rubber pads to prevent scratches. ⑵ plasma cutting: Plasma cutting, the cutting residue should be cleaned. Batch cutting for the completed parts should be promptly cleared the scene in order to avoid cutting the stain residue on the workpiece. ⑶ sawing Cutting: When cutting cutting, clamping rubber should be protected, clean the workpiece after cutting oils, residues, etc. 4.2.3 machining: stainless steel parts in the car, milling and other machining should also pay attention to protection, work to complete the surface should be cleaned of oil, iron and other debris. 4.2.4 Forming: in coil, bending process, should take effective measures to avoid surface scratches and creases stainless steel. 4.2.5 riveting: stainless steel pieces in the group should avoid forcing assembly, in particular, to avoid flame grilled school assembly. Group or production process where the temporary use of plasma cutting, isolation measures should be taken to avoid cutting stainless steel slag to other parts of the pollution. After cutting, the workpiece on the cutting residue should be cleaned. 4.2.6 Welding: welding stainless steel must be carefully removed before the oil, rust, dust and other debris. TIG welding as far as possible, using the manual metal arc welding should be used for small current, welding speed, to avoid the swing. Prohibited in the area of ​​non-arc welding, ground location suitable to connect securely to avoid scratches arc. Measures should be taken to prevent weld spatter (lime and other methods such as brush). Applied after welding stainless steel (not carbon steel) flat shovel and a thorough clean-up slag splashing. 4.2.7 multi-layer welding: Multi-welding, the slag layer must be removed. Multi-layer welding, interpass temperature should be controlled, generally no more than 60 ℃. 4.2.8 Weld: Weld joints should be grinding, weld surface may not have slag, porosity, undercut, spatter, cracks, lack of fusion, incomplete penetration defects, weld and base metal should be smooth transition, not low in the base metal. 4.2.9 orthopedic: orthopedic stainless steel parts, should avoid the use of flame heating method, in particular, repeated heating does not allow the same area. Orthopedic, try to use mechanical devices, or wooden hammer (rubber hammer) or a rubber mat mat hammer, ban hammer with a hammer to avoid damage to stainless steel. 4.2.10 Handling: stainless steel components for handling during processing, the application of means of transport (such as cars, electric vehicles or cranes, etc.), and isolation precautions have to be clean to prevent dirt, oil, pollution, rust stainless steel. Prohibited direct drag on the platform or ground, is strictly prohibited bump and scratch. 4.3 4.3.1 clean polished surface: if any damage should be polished, in particular, caused by contact with carbon steel scratches and splash, the damage caused by cutting slag must be carefully and thoroughly clean polished clean. 4.3.2 mechanical polishing: polishing to the use of appropriate tools for polishing, requires uniform treatment, and to protect against scratches and re-cast. 4.3.3 degreasing dust: stainless steel pickling passivation before making pieces, must craft clear oil, oxide, dust and other debris. 4.3.4 Water blasting: according to different processing requirements, use of different micro-glass beads, different process parameters, and to avoid overspray, etc. 4.3.5 Pickling Passivation: stainless steel pickling passivation parts must be in strict accordance with technical requirements for passivation. 4.3.6 Dry cleaning: pickling passivation, should be carried out in strict accordance with technical and, rinsing and drying to remove residual acid. 4.3.7 Protection: Stainless steel surface treatment has been completed, should be good protection, avoid touching people and oil, dust and other debris of secondary pollution. 4.3.8 to avoid re-processing: After the stainless steel surface treatment, avoid the parts or products of reprocessing. Yunqing brand stainless steel pickling additive uses: in stainless steel pickling process of adding nitric acid (HNO3) or sulfuric acid (H2SO4) in line with its use, to promote a variety of stainless steel black oxide, silicate removal of scale, reduce nitric acid or sulfuric acid corrosion of the metal matrix, while inhibiting the production of acid mist. In normal use to greatly reduce the corrosion rate of stainless steel, and excellent rejection of stainless steel in the pickling process of hydrogen absorption ability to avoid the occurrence of stainless steel “hydrogen embrittlement”, while inhibition of Fe3 + in the process of pickling of metal corrosion, the stainless steel pitting phenomenon does not occur. For various types of stainless steel. Features: powdery solid, with the use of low concentration, the effect is good, stable performance, simple operation, the amount of small, high efficiency, low cost; the corrosion of the metal matrix is ​​small, corrosion rate, the process does not mist, use safety. Usage: pickling: acid – washing – Shot Blasting – acid – wash – and in – washing – using hot water additive concentration is generally 5-10% (weight), the measurement of the additive metering water, stirring dissolved can. Can be added nitric acid or sulfuric acid, add additives, can be additive added nitric acid or sulfuric acid; room temperature or heated to 50 to 60 degrees to use, will have to deal with the stainless steel pieces soaked in cleaning solution, for 5 to 30 minutes or more time (processing temperature and time by the oxide thickness, plate material and processing requirements), to the surface oxide, rust completely cleaned, so far as silver, then with water (lime or alkaline better) rinse avoid back rust. Pickling temperature 48 degrees: 1 ton of water: 150L nitric acid: 30 kg additives pickling pickling pickling temperature 60 minutes at room temperature: 1 ton of water :200-300L nitric acid: 60 kg pickling additives pickling time is 40 minutes 1 tons of acid additives can handle 600 tons stainless steel (the data for reference only).

Stainless steel is the name given to a group of corrosion resistant and high temperature steels. Their remarkable resistance to corrosion is due to a chromium-rich oxide film which forms on the surface. When ordinary carbon steel is exposed to rain water, for example, it corrodes forming a brown iron oxide, commonly called rust, on the surface. This is not protective and eventually the entire piece of steel will corrode and be converted to rust. But when enough chromium (more than about 10%) is added to ordinary steel, the oxide on the surface is transformed – it is very thin, virtually invisible and protective in a wide range of corrosive media. This is what we call stainless steel and there are several different types, and many different grades. Types of Stainless Steel The basic composition of stainless steel is iron (Fe) and chromium (Cr). This is the simplest form of stainless steel, with this family known as the ferritic stainless steels because their crystal structure is called ferrite. (This is also the structure of mild steel.) The ferritic stainless steels are magnetic like ordinary steel. A commonly used grade is Type 430 (S43000) which is used for automotive trim and inside dishwashers and clothes dryers. They are often the least expensive stainless steels but can be more difficult to form and weld. If we wish to make carbon steel strong and hard, such as for a drive shaft or wear plate, we might increase the carbon content, and then heat treat the steel by quenching and tempering it. We can do the same with stainless steel – if we increase the carbon content of ferritic stainless steels we produce the family of martensitic stainless steels, used for items such as knives, razor blades and corrosion resistant bearings. Martensitic grades are strong and hard, but are brittle and difficult to form and weld. Type 420 (S42000) is a typical example. Like ferritic stainless steels, martensitic stainless steels are magnetic. The majority of stainless steels contain nickel (Ni), which is added for a number of reasons but particularly to change the crystal structure from ferrite to austenite. Austenitic stainless steels are ductile, tough and, most importantly, easy to form and weld. These steels are not magnetic in the annealed condition. The most common example is Type 304 (S30400) or “18/8” – the most widely used stainless steel in the world. The lower carbon version, Type 304L (S30403) is always preferred in more corrosive environments where welding is involved. There are numerous applications for this grade, ranging from domestic kitchen sinks and building facades to commercial food processing equipment and chemical plant piping. Molybdenum (Mo) is added to some stainless steels to increase their corrosion resistance, particularly in marine and acidic environments. It increases an alloy’s pitting and crevice corrosion resistance. These corrosion forms are caused by the common and highly aggressive chloride ion (Cl¯), which is present in salts, such as sea salt and table salt. When 2-3% molybdenum is added to Type 304 or 304L, we create Type 316 (S31600) or 316L (S31603) stainless steel. They are sometimes referred to as the marine grades of stainless steel, since they are widely used for items such as boat fittings. They are also known as the acid resistant grades, since they have better corrosion resistance in some acids such as sulphuric acid. But their range of applications is wide, from building facades in aggressive atmospheres to piping onboard chemical tankers. Halfway between the ferritic and austenitic stainless steels is a family called the duplex stainless steels, which are about 50% ferrite and 50% austenite. Because of this duplex structure, they are resistant to stress corrosion cracking, which can affect the austenitic stainless steels in hot waters containing chlorides. The most common duplex stainless steel is 2205 (including both S31803 and S32205) and it is used in many applications such as hot water tanks. Nitrogen (N) is added to some stainless steels, but is very important in duplex grades. It has several beneficial effects. Like nickel, nitrogen promotes austenite (especially important for welding) and, like molybdenum, it improves resistance to pitting and crevice corrosion. It also increases strength. Duplex stainless steels are inherently stronger, but a grade such as 2205, which contains about 0.15% nitrogen, has over twice the yield strength of Type 316L. Thus, 2205 is commonly used in tanks for seagoing chemical tankers where both strength and corrosion resistance are required, and for components such as rods and connectors for glass curtain walls in public buildings where the high strength means that the components can be small and so make the structure seem lighter and more transparent. There is one more family – the precipitation hardening stainless steels. This is a specialised family which has very high strength achieved by adding elements such as copper, which form very fine particles during heat treatment. They generally have slightly higher corrosion resistance than the martensitic stainless steels but, at best, they have slightly less resistance than Type 304. They are commonly used in the aerospace and defence industries, but also find use in items such as pump shafts. 17-4PH (S17400) is a typical example. In addition to the common grades mentioned above, there are many more specialised grades of stainless steel for applications which require greater corrosion resistance or higher strength. Three which are listed in the accompanying table are Alloy 904L (N08904), which was originally developed for sulphuric acid service, the super-austenitic grade Alloy 254 (S31254), representing a group of 6% Mo stainless steels; and the grade Alloy 2507 (S32750), representing a group of super-duplex alloys. The last two are ‘seawater resistant’ – they will not suffer pitting or crevice corrosion when immersed in ambient temperature seawater. There are also grades developed for such special needs as improved machinability. Cast versions of most wrought grades are also available, usually slightly modified to improve castability. Oil Companies are responding to the demand to operate their businesses in a sustainable way. Measures adopted include seeking to reduce emissions and to maximise their production of so-called “stranded” gas which otherwise can make no contribution to the world’s energy demand. In this climate it is likely that the oil and gas industry will increasingly seek to justify any aspect of its business, including its choice of materials, in order to boost its ‘sustainability rating’. Nickel-containing stainless steels and nickel alloys play an important role in providing corrosion resistant, and hence leak resistant, materials of construction for projects internationally. Some of these materials also play a critical role in handling gas production, particularly in liquefied form, thus helping to develop difficult-to-access gas reserves. Mechanical and Physical Properties For most corrosion resistant applications, strength is not a key issue. There are exceptions, such as pressure vessels, and here the high strength of duplex grades can make them attractive. A characteristic of the austenitic stainless steels is that they work harden easily – that is, their strength increases rapidly when they are formed at ambient temperatures, such as in rolling or wire drawing operations. The accompanying table (below) shows the large increase in strength of Type 304 in the 1/2 hard condition. This characteristic is valuable in items like bolts and springs. Two important physical properties are thermal conductivity and thermal expansion rate. The common austenitic stainless steels, such as Type 304, have lower thermal conductivity than carbon steels and this is useful in applications such as cappuccino cups and thermos flasks. Their rate of thermal expansion is also greater than ordinary steel (but less than materials such as aluminium) so care must be taken during welding to ensure that the recommended jigging and tacking procedures and welding sequences are followed. Corrosion Resistance When carbon steel rusts, it does so by uniform corrosion – the entire surface of the steel corrodes more or less uniformly. Except in special environments, such as strong acids, stainless steels do not corrode in this way. If corrosion does occur, it is normally by localised corrosion and the most common forms of this are as follows: Pitting is localised corrosion at inpidual sites on the surface of stainless steel. Pitting starts at points of weakness in the protective oxide film, such as at manganese sulphide inclusions on the steel surface. Crevice corrosion takes place where physical crevices are present, such as at the joint between two overlapping sheets of stainless steel, in the crevice between a stainless steel flange and a non-metallic gasket or under surface deposits. The mechanisms of pitting and crevice corrosion are similar and both most commonly occur in chloride environments. But crevice corrosion occurs more readily since it is assisted by the existence of a physical crevice, whereas pitting has to initiate on a surface which is effectively flat. It is often not possible to control environmental factors such as the amount of chloride or the temperature, so it is usually necessary to choose a sufficiently corrosion resistant grade for the service. An indication of pitting and crevice corrosion resistance is given by the ‘Pitting Resistance Equivalent’ (PRE) number: PRE = %Cr + 3.3%Mo + 16%N This formula shows the beneficial effect of chromium, molybdenum and nitrogen and illustrates why Type 316, with 2-3% Mo, has better resistance than Type 304 to marine environments. However, for resistance to corrosion when immersed in seawater on a longterm basis, it is necessary to move up to a grade with a relatively high PRE number, such as a super-austenitic 6% Mo grade or a super-duplex such as 2507. Chloride stress corrosion cracking (SCC) can occur in chloride-containing solutions at elevated temperature, normally above 50 degrees C, when tensile stress is present. It particularly affects austenitic stainless steels, and a common failure observed in the field is cracking from the outside of tanks or pipes carrying hot fluids. For example, if a water leak occurs into insulation on the outside, chlorides can concentrate through evapouration, and SCC can take place because of the tensile stresses present in the outside surface of pipes and tanks. Chloride SCC is most comonly overcome by using a duplex stainless steel, such as 2205, or a grade with a higher nickel content, such as a 6% Mo material or high-nickel alloys like Alloy 825 (N08825). Ferritic stainless steels are very resistant to SCC but grades with equivalent pitting resistance to the austenitic grades have other major drawbacks. Intergranular corrosion (IGC) is preferential attack at the grain boundaries of a stainless steel and is commonly associated with welding. If stainless steel is heated into a sensitising temperature range, such as can occur in the heat affected zone of a weld, then chromium can combine with carbon in the steel to form chromium carbides in the grain boundaries. Such a stainless steel is said to be ‘sensitised’. Around each chromium carbide particle is an area low in chromium so that, when the material is placed in a corrosive environment, attack of these low-chromium regions can occur. This is called IGC. The most common way today to avoid IGC is to specify a low carbon ‘L’ grade of stainless steel when welding, such as Type 304L . In the past, when it was difficult for mills to achieve low carbon levels, titanium (Ti) or niobium (Nb) were added since these elements preferentially combine with carbon and so leave the chromium unaffected. Grades containing these additions include Type 321 (S32100) containing Ti and Type 347 (S34700) containing Nb. Galvanic corrosion can occur when different metals are in contact in an electrically conductive liquid. Stainless steel is not normally corroded in such a galvanic couple, since it is usually the more corrosion resistant of the two metals and acts as the cathode. When the other metal which is in contact with the stainless steel is less corrosion resistant, it acts as the anode and corrodes preferentially. The rate of corrosion of the second metal can be rapid if its surface area is small relative to the area of the stainless steel cathode with which it is in contact. An example of this would be the use of galvanised steel fasteners to hold stainless steel sheets, a poor design unless the system is always dry. Galvanic couples are not necessarily a problem and can, in fact, be used to benefit in some designs. Applications Stainless steels find use in a very wide variety of applications. Some typical examples are: Consumer goods: Applications here include domestic kitchenware and tableware, kitchen sinks, laundry equipment and electrical and electronic appliances. Architecture, building & construction: Stainless steel has been used in numerous famous buildings. The Chrysler Building in New York, the world’s tallest building when it was built in 1929, used Type 302 (similar to Type 304) for the roof and upper structure. Type 316 is used to clad the outside of Petronas Twin Towers in Kuala Lumpur, currently the world’s tallest buildings, and Jin Mao Tower in Shanghai, the third tallest. More common applications are balustrades, column wraps, roofing and guttering, signage, curtain wall supports, light poles, elevator doors and public seating. Stainless steel rebar is used in bridges, barrier walls and decking to extend the life of critical areas of roadways and marine structures. Food and beverage industry: Type 304 and, in more aggressive situations, Type 316 are widely used in this industry for food and beverage production (milk silos, cheese vats, beer and wine fermenters, fruit juice tanks and piping), storage (wine tanks, beer kegs), cooking (large commercial kitchens) and serving (display cabinets, bench tops). Stainless steel equipment is easy to clean (sanitize) and also preserves the purity of the food. Transportation: A wide range of both decorative and functional components are fabricated from stainless steel, such as automotive exhaust systems, fasteners, trim, wheel covers and windscreen wiper arms; passenger railcars, coal wagons, bus frames and milk tankers; and seagoing chemical tankers. Chemical, petrochemical, oil and gas, pulp and paper industries, and power generation: This field represents a very persified market for stainless steel with many specialised applications such as heat exchangers, vessels for various types of chemicals, pipe, fittings, valves, pumps, mixers, high temperature furnace equipment, components for nuclear reactors, and gas and water turbines. End of Life When a system which uses stainless steel components reaches the end of its useful life, and if the equipment cannot be reused, it should always be recycled. Stainless steel, especially the nickel-containing grades, has a high scrap value and can be recycled to produce new stainless steel without any loss of quality. Most stainless steel today is made using a significant percentage of scrap stainless steel. Footnotes 1 High temperature grades and applications are not covered here. 2 The traditional AISI (American Iron and Steel Institute) numbering system groups stainless steels into 300, 400 etc series, such as Type 304, Type 430 etc. The newer UNS (Unified Numbering System) uses numbers of the form S30400 and S43000 for these same grades. Grade UNS No. Family Crc Nic Moc Nc C(max) Otherc PREc, e Yield strength MPa(min)b Tensile strength MPa (min)b Elong % (min)b 430 S43000 ferritic 17 0.12 17 205 450 22 420 S42000 martensitic 13 0.15 min 13 1480c 1720 8c 304 S30400 austenitic 18 9 0.08 18 205 515 40 304 ½ hard 760 1035 7 304L S30403 austenitic 18 9 0.03 18 170 485 40 316 S31600 austenitic 17 11 2.1 0.08 24 205 515 40 316L S31603 austenitic 17 11 2.1 0.03 24 170 485 40 904L N08904 austenitic 20 25 4.5 0.02 1.5Cu 35 220 490 35 2205 S31803 S32205 duplex 22 5 3 0.15 0.03 34 450 620 25 17-4PH S17400 precipitation hardening 16 4 0.07 4Cu 0.3Nb 16 1170 1310 5-10 Alloy 254 S31254 superdaustenitic 20 18 6 0.20 0.02 0.75Cu 43 300 650 35 Alloy 2507 S32750 superdduplex 25 7 4 0.28 0.03 42 550 795 15 a 0.2% proof stress b Annealed condition except for grades 420 and 17-4PH which have been heat treated and 304 ½ hard which has been cold worked, the intention in each case being to increase strength and hardness c Typical values d The term “super” is commonly used when the PRE number of the alloy is 40 or more e PRE = Pitting Resistance Equivalent (see text) By Gary Coates, Technical Director, Nickel Institute and Dr. David Jenkinson, Director Nickel Institute Australasia.

In the current metal pipe industry, small diameter, low pressure, mainly to carbon steel pipe fittings, mainly used in the metal pipe without special technical requirements of the operating environment, known as the general metal pipe; and large diameter, medium High pressure, the use of high-grade steel, alloy steel or special metal material manufacturing, its application of the industry has strong professional and targeted pipe fittings, known as the special steel pipe fitting industrys or high-end pipe fitting industrys. From the industrial metal pipe industry competition, the domestic production of metal pipe business is very large, but most of the smaller, mainly engaged in general metal pipe manufacturing, the real can produce high-quality, high-tech high-end metal pipe business is less. In the low-end pipe market, there is fierce competition. The supply and demand of high-end products such as large-caliber, composite materials and high-performance products are insufficient. The industry is in the low-end market and the high-end market is not perfect. China’s industrial metal pipe industry competition has the following characteristics: ① enterprises generally smaller scale. China’s annual production capacity of pipe fittings enterprises generally 1,000 tons in the following, most companies use small workshops, small factories type of production. On the one hand, the pattern of market demand caused by the other hand, most of the pipe fittings for private enterprises, by the capital, talent, market development and other factors, do not have sustainable development. ② enterprises lack the core technology competitiveness. The process of cutting, heat treatment, welding and anticorrosion of ordinary pipe production process is not high. The production process mainly depends on manual operation, basically do not use modern automatic control equipment, and do not have the technical innovation and product development ability. ③ product structure is irrational. China’s industrial metal pipe production capacity is mainly concentrated in the small and medium-diameter pipe fittings or carbon steel pipe fittings field, large diameter or high-end pipe production capacity is insufficient. China’s industrial metal pipe fittings enterprises from the product specifications, the main production of small-caliber tube; from the product material pision, the main production of carbon steel pipe fittings. The downstream market demand for large diameter products and high-performance alloy steel, stainless steel and new composite materials generally inadequate supply of the industry need to develop a number of carbon steel, stainless steel, alloy steel and other new composite pipe production capacity of enterprises, To solve the unreasonable product mix situation. ④ affected by the downstream industry fluctuations. The downstream industries of the industrial metal pipe industry are the lifeline industries of petrochemical, shipbuilding and electric power industries. These industries have high market concentration and some enterprises are monopolized or semi-monopolized, and can rely on huge demand to form buyer monopolies. The industrial metal pipe industry, market concentration is low, a single enterprise market negotiation capacity is limited, product sales by the downstream industry as a whole the greater impact of volatility. Industrial metal pipe fittings mainly for supporting the use of downstream industries, industry enterprises are mainly distributed in the petrochemical, shipping, electricity and other downstream industries concentrated in the eastern region. The rapid development of the downstream industry will drive large diameter, composite materials, high performance and high reliability of the strong demand for pipe fittings, especially with China’s urbanization infrastructure to accelerate the development of the central and western regions, oil and gas field development, the world ship order transfer, Resource exploration, construction of nuclear power plants and other construction projects, will have been in short supply the market there is a greater gap between supply and demand. Therefore, large-diameter, composite materials, high-performance and high reliability of the pipe fittings production enterprises will gather in China’s industrial metal pipe the most competitive areas. Industrial metal fittings industry regional agglomeration characteristics are obvious, mainly in the east and north China, the main industrial agglomeration area has four: Jiangsu Jiangyin, Yangzhou area; Hebei Cangzhou, Langfang area; Liaoning Yingkou, Fuxin area; Zhejiang Wenzhou area. The following are the number of competition from the industry, industry growth rate, exit barriers, competition analysis of the existing competition in the enterprise. Analysis of available, the industry is in the mature stage, the quality of the industry as a whole uneven, most enterprises focus on low-end products, price war, the existing business competition. Table 2: Competitive analysis of existing metal pipe fittings Indicators Performance Conclusion Number of competitors Numerous enterprise data, mainly small and medium-sized enterprises, the total number of more than 4000 enterprises, the annual income of more than 20 million yuan about 200 enterprises, listed companies only one. Competitors are numerous Industry growth rate In recent years, industry production and sales are rising trend year by year, average annual growth rate at about 15%, but growth downward. Industry growth rate is higher, but growth showed a trend of decline Exit barriers Industrial metal pipe fitting belongs to the manufacturing industry, the fixed cost is greater. Large exit barriers The degree of homogeneity Domestic industrial metal pipe fittings production enterprise on a smaller scale, most companies focus on low-end products, high-end products focused on leading enterprises, high-end products created value accounts for more than 60% of the whole industry. Low degree of product homogeneity Competitivelevel Low-end products market competition is given priority to with price war; High-end product market competition is given priority to with technology and brand. Higher competition level With the international industrial gradient transfer, manufacturing has been to China, India and other developing countries. Therefore, foreign companies on the domestic industrial metal pipe fittings business a smaller potential threat. At the same time, China’s industrial metal pipe industry has matured, new entrants into the cost of a higher threshold. As a result, the potential threat to China’s industrial metal pipe fittings is small. Industrial metal pipe fittings is an essential part of industrial pipe, there is no substitute products; but with the downstream industry of industrial metal pipe product quality, material and other requirements, there are high-end products in the low-end products instead. Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)