steel pipe

　　First, preheating 　　Preheating is beneficial to reduce the maximum hardness of the heat affected zone of medium carbon steel and prevent cold cracks. This is the main process measure for welding medium carbon steel. Preheating can also improve joint plasticity and reduce post-weld residual stress. Generally, 35 and 45 steels have a preheating temperature of 150 to 250 ° C or a high carbon content or a large thickness and rigidity. When the crack tends to be large, the preheating temperature can be raised to 250 to 400 ° C. 　　If the weldment is too large and the overall preheating is difficult, local preheating may be performed. The heating range of the local preheating is 150 to 200 mm on both sides of the welded joint. 　　Second, the electrode 　　Basic electrodes are preferred when conditions permit. 　　Third, the groove form 　　Weld the weldment as much as possible into a U-shaped groove for welding. In the case of casting defects, the shape of the groove excavated by the s...

　　Production of large diameter spiral tubes during production has many influencing factors. In production practice, steel pipes are often degraded by drying and the wrong side. Therefore, it is necessary to analyze the causes and preventive measures of the wrong side of the large diameter spiral pipe. Many manufacturers produce large diameter spiral tubes. Although they can be produced, there are quality differences, so each manufacturer's sales are different and are heavily influenced by quality. The quality of large diameter spiral tubes is an important factor in determining their use. If quality is not guaranteed, how many people will continue to use it? 　　Large diameter spiral tubes have a wide range of applications. It is trusted by many industries and its quality is also a big advantage. Now, the products are worth the quality of the products, the same price will choose the quality. If the price is different, then many people would rather spend more money to choose the pro...

　　1. The surface of the 304 stainless steel plate is very beautiful, and because of its very plasticity, there are many possibilities for processing, which gives more room for processing. 　　2, 304 corrosion resistance is very good, compared to other steel, 304 products have better durability. 　　3, 304 products are relatively high in strength, especially in the high temperature and oxidation resistance, to a certain extent have a fireproof effect. 　　4, 304 products can be directly processed at room temperature, which has great convenience for processing. 　　5. The surface of the 304 product is very easy to handle, even in some respects, it is easy to use and relatively easy to maintain, and the surface finish is high. 　　6, 304 products have very good welding performance, can be easily completed, and it is not easy to cause damage to the product itself.

　　The anti-corrosion of buried seamless steel pipe is the key procedure to ensure and extend the service life. In order to ensure the firmness of the anti-corrosion insulation layer and the pipe wall, the derusting of the pipeline is the most important. 　　Generally, according to the factory time, storage and transportation conditions, and the degree of humidity in the climate, the rust on the surface of the American standard steel pipe can be divided into floating rust, medium rust and heavy rust. 　　Floating rust: Generally, when the factory date is short, when it is not stored in the open air, there is only a small amount of thin rust on the surface of the pipe. The metal luster can be exposed by manual operation such as wire brush, sandpaper and cotton yarn. 　　Medium rust and heavy rust: When the date of manufacture is long and open storage or multiple transfer and long distance, the surface of the pipe will be oxidized and rusted, and its rust spots will be heavier. In severe ...

　　Cold-formed steel, cold-formed rectangular tube through the one-way roller contacts the outer tube forming the outer wall so that the strip bending moment, bending line will produce cold-formed compression, the compression effect makes bend lines longitudinally elongated, bent accumulation of the metal appears thicker, which is cold-formed compression / thickening effect. 　　1) The advantage of cold-formed is small rebound, forming accurate, and as long as the roller type accurately, inside corner molding R more accurate. The advantage is that it can be cold-formed side bent when you can not be cold-formed, for example, square and rectangular tube top / side synchronous bending and finishing. You can also cold-formed bent R <0.2t inside corners and walls without fracture. 　　2) There is a disadvantage of cold-formed stretching / thinning effects. It will produce cold-formed bends stretch, stretching effect of the longitudinal length of the bend lines shortened; second, cold bend...

　　Fault erw steel pipe unit is relatively more, and the cause of the failure is also more complex, the result is often caused by a variety of reasons, can be caused by several reasons or a result. 　　Scratch Tube welding machine appeared scratches caused mainly by two parts, one guide means, and second extrusion welding mechanism. 　　Squeeze roller scratches caused, mainly in the bottom of the tube, because generally have the following points: 　　(1) Does not match the pass 　　Weld extruded structure has two roll, three-roll and four-roll type, as long as the combination of the hole do not match, it is likely to cause the tube surface scratches, especially two roll structures. Factors that do not fit and pass a lot, a two-roll structure as an example, such as bearing damage; roller axial movement; pass sample sizes; two roller height position is not the same; shaft bending and assembly of instability and so on. 　　(2) Height match 　　Squeeze roll pass the lower edge should roll ...

　　Straight seam high frequency ( ERW ) by welding and induction welding is divided into different forms of contact of two welding, hot-rolled wide coil as raw material, through pre-bending, continuous forming, welding, heat treatment, sizing, straightening, cutting, etc. step short compared to the spiral weld, high dimensional accuracy, uniform thickness, surface quality, under pressure advantages, but the disadvantage is that only the production of small diameter thin-walled tube, easy to produce gray leaf spot weld, incomplete fusion ditch-like corrosion defects. Currently wider field of application of city gas, crude oil and other oil products transportation. 　　Spiral submerged arc (SSAW) pipe volume is the forward direction of its centerline forming tube forming angle (adjustable) while forming side welding, weld into a helix, the advantage of the same specifications can produce a variety of diameters steel, adapt to a wider range of raw materials, the main seam can avoid stress,...

　 　What is the black pipe? 　　 Black steel pipe is made of steel that had not been galvanized, Its name comes from the scaly, dark-colored iron oxide coating on its surface, It's used in applications that don't require galvanized steel. 　 　What is carbon steel pipe? 　　Steel whose characteristics are determined by the amount of carbon it contains. And steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, niobium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 percent; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60. 　　Most the steel produced in the world falls into the category of carbon steel. 　　Difference between black pipes and carbon pipes 　　In general "blac...

　　(1) Source of evaluation of external coating 　　Literature states: "steel surface condition is called environment that can coating and soil pipe insulation four weeks, four weeks the tube surface soil conditions are different and therefore the corrosion protection layer of the pipe is an important barrier to prevent soil erosion. " This is the basic starting point of the evaluation outer coating performance. Joe Leighton British company discussed from two different perspectives pipe coating system: European perspective is to make it able to withstand moisture, prevent corrosion, it is the "barrier" point of view. From this point of view it had a "PE" protective layer method. The North American point of view is to make it possible to oxidation resistance, chemical resistance and resistance to negative release properties to prevent corrosion, which is the "glue" point of view. From this point of view, resulting in a "FBE" law protectiv...

　　1. The material 2. Design problem and 3.Application problems. 　　1.Material: the main parts of the gantry scaffolding tube steel pipe. According to the standard requirements, the doors scaffold should use 48 mm outside diameter, wall thickness of 3.5 mm carbon steel pipe welding. 　　This kind of steel pipe due to the thickness of the moment of inertia to make lose 10%, use the rust after a long time can cause wall thickness is thinner and moment of inertia will also reduce, so will become a safety hazard. 　　2. The design problem: activity scaffolding collapse is the main reason of the support is not stable. Before construction, many enterprises were not scaffolding stiffness checking, just rely on experience support system, the insufficient scaffolding tube rigidity and stability of the support system to consider. Other steel pipe due to corrosion or wear and tear, and the local bending, welding, will lead to the actual bearing capacity to reduce a lot of steel tube, it is easy ...

　　The seamless steel pipe is a steel pipe without weld seams produced by a perforated hot rolling method. It is sometimes necessary to further cold work the hot worked tube in order to obtain the corresponding shape and size. The carbon steel pipe is generally made into a round, square, flat shape by multiple rolling. 　　Seamless steel pipes are the most used pipes in today's petrochemical production plants. Carbon steel pipes are more widely used. At the same time, the main requirement of the carbon steel pipe is its carbon content. The seamless steel pipe is a large type, and the steel pipe is seamless and has a wide range. 　　The mechanical properties of steel are generally expressed in the following aspects: 　 　1. Yield point (σs) 　　When the steel or specimen is stretched, when the stress exceeds the elastic limit, even if the stress does not increase any more, and the steel or the specimen continues to undergo significant plastic deformation, the phenomenon is called yi...

　　The seamless steel tube is bent because the rolling mill is not properly adjusted, the residual stress remaining during rolling, and the unequal cooling due to the cross-section and length of the tube. Therefore, it is impossible to obtain a straight steel pipe directly from the rolling mill, as long as the tortuosity of the cold straightening steel pipe is sufficient to satisfy the rules of the skill condition. 　　The straightforward principle is to make the seamless tube elastically and plastically bend, and the large bending degree becomes a small degree of curvature, so that the steel pipe needs to be repeatedly bent in the straightening machine. The degree of repeated bending of the steel pipe is mainly determined by the adjustment of the steel pipe straightening machine. There are many factors that affect the quality of straightening, such as the bending of the original pipe, the size of the steel pipe and the type of material straightening machine, and the adjustment paramete...

　　 SSAW steel pipe often there will be some quality problems in the production and use, affecting normal use in some aspects, the need for spiral welded pipe to identify the quality, according to a certain way and performance testing, can produce significant in actual use role, then how to identify counterfeit spiral welded pipe method: the appearance often pockmarked face phenomenon. Generally the whole proportionate amount would be better, mainly taking into account the cumulative error and probability theory this problem. Some of the above please add if inadequate, we welcome the discussion of knowledge about aspects of the steel pipe together, advances constantly exchange. Pock is due to badly worn groove spiral welded pipe surface irregularities caused by uneven defects. Because of shoddy spiral welded pipe manufacturers have to pursue profits, rolling groove most often exceeded. The surface is easy to produce scarring. 　　Quality spiral welded pipe of uniform composition. High ...

　　At present, ordinary fluid on the market with the general Longitudinal Welded Pipe is generally used in high-frequency resistance welding production, which is characterized by high production efficiency, weld heat affected zone is small, low quality requirements on the bonding surface, but the molding quality requirements, forming process Any change in the shape of the V-shaped opening may cause welding quality problems. 　　Rolling groove processing is the use of grooved joints as pipe fittings when the pipe pretreatment process. Its operating principle is the use of roll groove rolling machine driven rotating pipe, pipe radial direction of the follow-up pressure roller radial pressure applied to the use of the structure of the pressure roller welded pipe in a fixed position of cold out a specified groove. 　　A "roll groove cracking" is the root cause of the weld strength is not enough, coupled with rolling groove processing of the severe deformation, resulting in weld st...

　　Classfication of seamless steel pipe by application 　 　1. Line pipe. 　　Such as: water, gas pipes, steam pipes seamless pipe, oil pipeline, oil and gas line pipe. Agricultural irrigation faucet with pipes and sprinkler pipe. 　 　2. Thermal equipment tube. 　　Such as general boiler boiling water pipe, superheated steam pipes, locomotive boiler superheater tubes, opium pipe, small pipe, brick arch pipe and high-temperature high-pressure boiler tubes. 　　 3. Mechanical industrial pipe. 　　Such as aviation structural tube (tube, oval tube, flat oval tube), automobile axle tube, axle tubes, structural tubes automobile and tractor, tractor oil cooler tube, farm with a square tube and rectangular tube, transformer tube and bearing tubes. 　 　4. Petroleum geological drilling pipe. 　　Such as: oil drilling pipe, drill pipe (Kelly and hexagonal drill), drill collar, oil tubing, casing and various fittings, geological drilling pipe (core pipe, casing, active drill pipe, drill collar p...