ERW Steel Pipe

　　Generally, in terms of the surface treatment for stainless steel pipes , manufacturers have three methods, blenching treatment, polishing treatment and coloring treatment. However, it’s unavoidable to have some problems during the surface treatment, mainly are the following problems. 　　1. Defects of welding crevice. When the defects are serious, usually can apply the mechanical polishing process to deal it, however, this method may cause grinding marks and result in the uneven surface and influence the appearance of pipes. 　　2. Uneven surface. If only give pickling passivation to welding crevice, it will also cause the uneven surface and affect the appearance of pipes. 　　3. Uneven polishing. For the lager object, carrying pickling passivation after manual polishing is also difficult to reach the even surface and the processing is time and cost consuming. 　　4. Limited capacity of acid washing. The pickling passivation is not a panacea for all kind of surface treatment. It’s al...

　　Mechanical properties of seamless steel should be taken into consideration when testing its hardness which related to the quality and performance after deformation, stamping, cutting and other processing. Thus, all seamless steel pipes need mechanical property test, the test has two types: tensile test and hardness test. 　　Tensile test is use a seamless steel pipe sample, and then pull the sample on the machine till it’s broken, therefore can test its tensile strength, yield strength, and elongation. The tensile test is the most common method to test the mechanical property of metal material. As long as the mechanical property is required, all metal material need to have tensile test. Particularly for those metal materials have complicated shapes that are not easy to be tested, the tensile test is the only way to test its mechanical property. 　　Hardness test is use a indenter and pressed it into the surface of sample pipes slowly, then measure the depth or dimension of the inden...

　　The bearing capacity of spiral welded steel pipe is related to two points. One point is the mechanical properties of steel, which is related to the commonly stated yield point, tensile strength, elongation and impact toughness. The other point is related to the geometrical characteristics of its section. Generally, a circular spiral welded steel pipe has the strongest resistance to local buckling, and thus it is the best member to withstand radial internal pressure and radial external pressure. 　　Under the same steel number, equal area and the same supporting conditions, the rectangular slanted steel pipe has strong eccentric compression bearing capacity, and the circular and square steel tubes have the strongest compressive bearing capacity, but the square and rectangular straight seam steel pipes are subject to the ability of the nip to resist local buckling is not as good as that of a circular steel tube. Compared with spiral welded steel pipe, the seamless steel pipe has compli...

　　 Seamless steel pipes are widely used in various fields, but how to distinguish their quality? Here we will introduce you some way to distinguish. 　　1. Fake seamless steel pipes are easily to have puckers. Puckers referring to all folding lines on the surface of pipes, and the defects are usually longitudinally throughout the entire product. The primary reason for puckers is that manufactures are blindly pursued for high efficiency via wrong technique that cause ear and produce folds in next procedure. The folded pipes are easily to crack and the strength is also greatly decreased. 　　2.The fake pipes generally have pitting surface. Grooves with serious abrasion were the major reason for irregular and uneven defects on pipes' surface. Some manufactures just focusing on profits and often make excessive the groove rolling. 　　3. The surface of fake pipes is easily tended to produce scars. There are two reasons for scars. Firstly, the fake pipes were made of uneven material wit...

　　1. Due to the arc deviation, local distortion of longitudinal seam welding, The radian and ovality deviation of steel pipe will be difficult to ensure the deviation, and it take the following measures to guarantee. 　　(1) To design and produce longitudinal seam local arc calibration machine, after welding longitudinal seam, to use machine calibration to ensure its partial arc deviation. 　　(2) Set up the reasonable steel pipe support to ensure deformation value and ovality of steel pipe. 　　2. In order to ensure the straightness of the deviation when steel pipe assembling, following measures can be taken. 　　(1) Improving groove design, adopting asymmetric X groove, leaving no space, cleaning with carbon arc air gouging after the inseam welding, making inside and outside of the weld actual area is almost close to equal, these measures are helpful to reduce the deformation and the residual stress. 　　(2) Improving welding technology taking small-area welding, especially the first...

　　Hot-rolled is based on the slab (mainly billet) as raw material, heated by a roughing mill and finishing mill group made of steel. From finishing the last one out of the hot strip mill by laminar cooling to the set temperature, the coiling machine rolled steel strip coils, steel roll cooled through different finishing line processing and become steel, flat volume and slitting steel products. Cold drawing means at room temperature, after cold-drawing, bending, drawing and other cold plate or strip into the processing of various types of steel. 　　Hot-rolled and cold-rolled difference: 　　1, Hot rolling and cold drawn steel or steel plate forming process is the same, they have a great impact on the microstructure and mechanical properties of steel, rolled steel, hot-rolled mainly based, cold-rolled steel used only for the production of small and sheet. 　　2, Cold- formed steel cross-section appears to allow local buckling, which can make full use of the rod bearing capacity after bu...

　　Anti-corrosion steel pipe is processed through the preservation process, which can effectively prevent or slow down the process in the transport and use of chemical or electrochemical corrosion reaction of steel pipe . 　　Anti-corrosion steel pipe in the country is mainly used for petroleum, chemical, gas, heat, sewage treatment, water, bridges, steel pipes and other engineering fields. Anti-corrosion steel pipe is divided into the following categories: IPN8710 corrosion, FBE epoxy powder corrosion, 2PE/3PE corrosion, Coal tar epoxy anticorrosive, High-density polyethylene jacket corrosion 　　 The processing standard: 　　1.The petroleum natural gas uses three polyethylene (3PE) Steel pipe anticorrosion 　　Standard: SY/T0413-2002\DIN30670-1999 　　2. fluming water, oil, gas Medium and so on use two, three polypropylene (PP) anticorrosion 　　Standard: DEP 31.40.30.31 　　3. The petroleum natural gas uses FBE(Single-layer nodulizing epoxy powder anticorrosion) 2FBE(Double-decked no...