Chase Liu

1. Reduce project cost According to calculations by relevant departments, double-pipe heating pipelines can generally reduce the project cost by about 25% (using glass fiber reinforced plastic as a protective layer) and 10% (using high-density polyethylene as a protective layer). 2.Low heat loss and energy saving The thermal conductivity of the direct buried insulation pipe is: λ=0.013-0.03kcal/m·h·oC, which is much lower than other commonly used seamless  steel pipe insulation materials in the past, and the insulation effect is improved by 4~9 times. In addition, its water absorption rate is very low, about 0.2kg/m2. The reason for the low water absorption rate is that the closed-cell rate of polyurethane foam is as high as about 92%. Low thermal conductivity and low water absorption, coupled with the insulation layer and the high-density polyethylene or glass fiber reinforced plastic protective shell with good waterproof performance on the outside, have ... Continue reading →

There are many quality inspection methods for steel pipes (seamless pipes or welded pipes), and physical methods are the most commonly used ones. Physical inspection is a method of measuring or inspecting certain physical phenomena of steel pipes. Generally, non-destructive testing is used to check internal defects of materials and workpieces. At present, there are methods such as ultrasonic flaw detection, magnetic flaw detection, radiographic flaw detection and penetrant flaw detection. 1. Magnetic test Magnetic flaw detection is to use the change of the magnetic field of the metal part in the magnetic field to find the defect. According to different detection methods, it can be divided into magnetic induction method, magnetic powder method and magnetic recording method, among which the magnetic particle method is the most widely used. 2. Penetration inspection Penetrant inspection is to use the permeability of a certain liquid to find defects in steel pipes, including fluorescent ... Continue reading →

With the development of continuous rolling production of strip steel and the advancement of welding and inspection technology, the quality of weld seams has been continuously improved, and the varieties and specifications of welded pipes have increased day by day, and more and more seamless pipes have been replaced. Welded steel pipes are cheaper than seamless steel pipes and are more widely used in production. In recent years, most oil and gas pipelines in the world have required the use of straight seam welded pipes. Western developed countries such as Canada have improved the process of spiral welded pipe (SSAW pipe). Such as pre-welding, finishing welding, multi-wire welding and mechanical expansion, etc., are all designed with reference to the technology of straight seam submerged arc welded pipe (LSAW pipe), which reflects the advancement and superiority of straight seam welded pipe control technology. Specifically include: From the perspective of being suitable for offshore oil ... Continue reading →

With the development of ERW pipe technology, its application fields continue to expand. ERW steel pipe uses the skin effect and proximity effect of the current to heat the edge of the tube blank to the welding temperature for extrusion and welding. Compared with seamless pipe, it is obvious that ERW pipe has a weld seam, and its performance depends largely on the quality of the weld seam. The factors affecting the quality of welds are more complicated. Including the chemical composition of raw materials, inclusions, banded structure, sickle bend, plate edge burrs, etc. will affect the quality of the weld, and the inclusions and banded structure have a great impact on the impact toughness and flattening performance of the weld. Excessive inclusions tend to accumulate in the heat-affected zone of the weld, and easily form crack sources to cause cracking. When the camber and edge burrs are serious, it will cause misalignment, arc strike, weld deviation, inclusions are difficult to ... Continue reading →

The purchase of large-diameter straight seam steel pipes (LSAW pipes) should be communicated in advance. Before purchasing steel pipes (seamless pipes or welded tubes), you should follow the pre-designed specifications, length, material, wall thickness, welding standards and weld seam requirements. These must be communicated before purchase. The first is the specification, for example, 800mm is also called DN800, including 820mm and 813mm of A and B series, or the outer diameter of 800mm must be clearly specified to avoid unnecessary losses. The wall thickness of large diameter straight seam steel pipe is required to be 16mm. It is possible that the actual thickness of the raw material will be 15.75mm and 16.2mm, and there will be upper or lower differences, which are normal deviations. Because straight seam steel pipes are priced per ton, communication is required in advance to avoid weight differences. The normal length of large-diameter straight seam steel pipe is 12m. When the ... Continue reading →

When seamless steel pipes are put into use, quality inspection is often required to judge whether they are qualified or not. 1. Chemical composition analysis. Instrumental analysis and chemical analysis can be used. The samples used for chemical analysis are divided into smelting samples, ingot cuttings samples, and pipe samples. The smelting sample generally adopts the instrumental analysis method, and the finished pipe sample adopts the chemical analysis method and the co-analysis method. 2. Size and shape detection. The inspection contents mainly include wall thickness, outer diameter, length, curvature, ovality, port slope, obtuse angle and cross-sectional shape of special-shaped steel pipe. 3. Surface quality inspection. There are many non-destructive testing methods for manual visual inspection and non-destructive testing, such as ultrasonic testing, eddy current testing, magnetic particle testing, magnetic flux leakage testing, electromagnetic ultrasonic testing and penetrant ... Continue reading →

Welding technology for directly welded steel pipes: the use of small-scale models can avoid stress corrosion, thermal cracks and deformation, and the welding current is 20% lower than that of high carbon steel. In order to ensure that the electric isolation is ignited, a DC reverse connection is used. The short arc welding strategy should slowly stop loneliness, add electrical craters, and finally weld and contact the surface of the material. In the multi-layer high-rise electric welding, the temperature of the virtual beam should be controlled, and forced water cooling can be used after welding. Arc welding: used for arc welding of lsaw, good maintenance, good welding high temperature performance, good physical properties, aluminum alloy parts are not easy to burn, high connection index, good welding formability, no dross shell, smooth surface. At present, the manual tungsten argon arc welding market is mainly used for the welding of 0.5~3mm stainless steel plates by argon arc ... Continue reading →

Welded steel tube refers to a steel strip or steel plate that is bent and deformed into a round, square or other shape and then welded into a steel tube with seams on the surface. So how can the steel strip or steel plate be welded together? What are the skills in welding?   1. According to the application, the welded steel tube has general use and high temperature and high pressure, etc. The pipes used in the latter are often special alloy steels. The problem of shrinkage cracks in the welding seam during the welding process must be considered and solved, as well as the heat-affected zone tubes. Mechanical properties do not change too much due to welding operations.   2. According to the thickness of the tube wall, tubes made of relatively thin materials such as steel strips can be welded by high frequency welding, and some thin-walled tubes can be welded by shielding gas method; pipes with a wall thickness exceeding 2mm can be welded by hand arc welding.   3. ... Continue reading →

Seamless pipe is a steel pipe made of whole round steel perforated without welded seams on the surface. According to its production process, it can be divided into cold drawn seamless tubing, hot-rolled seamless pipe, extruded pipe, top pipe, etc., all of which have their own process regulations. It is widely used in pipelines for transporting oil, natural gas, gas, water and certain solid materials, etc.   With the popular application of seamless pipe in the construction industry, its quality is prone to problems, so how to identify the shoddy seamless pipe?   1. Shoddy seamless pipe easy to fold   Folding is a variety of folding lines formed on the surface of the seamless pipe, and this defect often runs longitudinally throughout the product. The reason for folding is due to the pursuit of high efficiency by shoddy manufacturers, the amount of press down is large, generating ears, and the next rolling produces folding, and the folded product will crack after bending, ... Continue reading →

Due to the limited pressure of the press, the thickness of the wall thickness of the straight seam steel pipe(LSAW pipe) can reach a maximum of 50mm. If the pressure exceeds 50mm, the pressure cannot be reached, and only seamless steel pipes can be used. The thinnest straight seam steel pipe wall thickness is 8mm. Because the production of straight seam steel pipe, the first step is to press the steel plate into a circular shape, so the steel plate needs to have a certain thickness. If the steel plate is too thin, the press cannot crush the steel plate; if it is pressed less than the thinnest steel plate, severe deformation will occur. Even when production is complete, it is oval. Therefore, the thinnest straight seam steel pipe wall thickness can reach 8mm. Can straight seam steel pipe be used as seamless steel pipe? Nowadays, competition in all walks of life is very fierce, and the straight seam steel pipe industry is no exception. To increase profits, many manufacturers use ... Continue reading →

  Cold  drawn seamless pipes are precision steel pipes with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment. Widely used in petroleum, chemical industry, boilers, power stations, ships, machinery manufacturing, automobiles, aviation, aerospace, energy, geology, construction and military industries. In the production process, the quality of cold drawn seamless pipe is good and bad. In order to save resources and improve material utilization, it is necessary to analyze and control the defects in the production process of cold drawn seamless pipe. So what are the defect control methods?   Defect control of cold drawn seamless pipes: 1. Control the carbon content in the steel as much as possible to avoid the peritectic reaction zone and control the upper or lower limit. 2. The vibration stability should be monitored to ensure that the lateral deflection of the vibration is not greater than 0.2mm and the longitudinal ... Continue reading →

  Seamless steel pipe refers to the whole round steel perforated, no welded seam on the surface of the steel pipe, widely used in the manufacture of structural and mechanical parts, such as oil drilling rods, automotive drive shafts, bicycle frames and steel scaffolding used in building construction with steel pipe manufacturing ring parts.   Seamless steel pipe accepted load method is not the same, the choice of rolling bearing collaboration should be different level of tightness, when the acceptance of fixed immobile load, collaboration should be loose, so that rolling bearings in machinery and equipment with demolition more convenient, but can not be too loose, or it will cause dragging in the collaborative parts and make the collaborative surface wear, therefore, should generally take the articulated collaboration or have very little clearance gap collaboration.   Seamless steel pipe inner and outer wall high precision, smoothness. After heat treatment, seamless ... Continue reading →

  Straight seam steel pipe refers to the steel pipe with the weld seam parallel to the longitudinal direction of the steel pipe. Its production process is simple, the production efficiency is high, the cost is low, and the development is fast. Mainly used for large-span grid engineering, building steel structure engineering, electric power and ultra-high voltage transmission and distribution engineering, mechanical engineering, cross-sea bridges, bridges, (steel structure engineering of railway stations, airports, stadiums), municipal pipe networks, foundations Ancillary facilities such as piling, water and gas pipelines and road construction. Common methods for the production of large-diameter straight seam steel pipes: 1. The pipe blanks (plates, strips) are directly formed and welded into pipes, and the main processes are strip forming, welding, and sizing. Features: few production processes, simple engineering process, short product production cycle, slightly lower product ... Continue reading →

When galvanized seamless steel pipe needs to be stored and transported tightly, appropriate precautions should be taken to prevent white rust. Maintain a low humidity environment around plated parts and ensure adequate ventilation between stacked plated parts to reduce white rust. The specific method is as follows: 1. Surface treatment can reduce the generation of white rust. 2. The coating should be stored in dry and well-ventilated conditions. 3. If the coating can only be stored in the open air, the coating should be separated from the floor by a narrow partition so that air can flow freely to all surfaces of the coating. 4. Do not place coated parts in places that may be affected by rain, fog, condensation and snow. 5. Galvanized steel should not be consigned to the surface of the ship or placed at the bottom of the ship to avoid contact with bilge water during shipping. Knowing how seamless steel pipes prevent white rust, do you want to know what black steel seamless pipes are ... Continue reading →

When a layer of zinc is applied on the surface of the steel pipe, it can be called a galvanized sheet; the galvanizing on the surface of the steel sheet is to allow the product to better prevent corruption. In fact, galvanized sheet has different treatment methods in the coating process, and the state presented on the surface, such as ordinary spangle, flat spangle, fine spangle and no spangle. Due to the variety of seamless pipes sizes, they are widely used and also appear in small auto parts. What are the treatment methods of hot-dip galvanized seamless steel pipe? 1. Passivation: the galvanized sheet is passivated to reduce rust in the humid environment of storage and transportation. The technical performance of this chemical analysis treatment is relatively limited and will hinder the adhesion of most coatings. This method is not usually used for zinc-iron alloy coatings, except for conventional surface treatments, other types of zinc passivation layers. 2. Oiling: In fact, the ... Continue reading →

  Under the same diameter of large-diameter cs seamless pipe, increasing the strength can reduce the thickness of the pipe wall. In either case, increasing the strength can also reduce the weight of the steel pipe per unit length. Even if the weight reduction rate is not large, the cost of steel can generally be reduced, thereby reducing the transportation cost of steel pipes. Excavation and circumferential welding costs for laying trenches. In this case, high-strength pipeline steel pipes are used for development and application. After several years of hard work, large-diameter seamless steel pipes have formed a full-standard variety structure system. In the oil and gas pipeline, building structure, petrochemical industry, complete specifications, high quality and fast delivery.   At this stage, large-diameter seamless steel pipes are very important in industrial production. Do you know what advantages it has?   According to its name, it can be seen that the large ... Continue reading →

  Defects in welding of erw steel pipes and their prevention   Inclusions The formation mechanism of the inclusion defect is that the metal oxide is not extruded with the molten metal, but is sandwiched in the welding fusion surface to form a defect. A defect of this type is that the metal oxide is not trapped on the fusion surface as the molten metal is extruded. These metal oxides are formed on the molten metal surface of the V-shaped mouth. In the V-shaped mouth, if the approach speed of the edge of the steel strip is less than the melting speed, the melting speed is higher than the molten metal discharge speed. And the narrow fan-shaped region of metal twisted oxide, these molten metal and metal oxide cannot be completely discharged by normal extrusion, thus forming an inclusion zone.   Precaution: 1) The V-shaped angle is controlled between 4 degrees and 6 degrees; 2) Reliable tooling and equipment installation to ensure a stable V-shaped mouth length; 3) ... Continue reading →

  The air oxide film on the surface of the cold drawn seamless tubing  is thin and high in density, and it is not easy to fall off. Under normal circumstances, the cold drawn seamless tubing will cause an oxide scale of 0.2 to 0.3mm in the heat treatment equipment. Defects can be removed with air oxidation of galvanized iron. If the defects are not within this range, the surface defects on the billet will inevitably be brought into the final product if they are not treated in all aspects. Cold drawn seamless tubing generally cannot use flame to eliminate surface defects of the billet. Flame elimination will cause changes in the composition and crystal phase composition of the region where the billet is eliminated, which will affect the corrosion resistance of the sheet. Therefore, industrial equipment elimination is a widely effective method for sheet metal surface solution. The general methods include air oxidation galvanized iron cleaning mechanical treatment, water ... Continue reading →

What is seamless pipe?   Seamless pipe means a steel pipe that is perforated from a whole round steel and has no welds on the surface. Because the seamless pipe has a hollow section, it is widely used as a pipeline for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, the steel pipe is lighter in weight when the bending and torsional strength is the same, and is an economical section steel.   Classification of seamless pipes according to carbon content   1) General carbon content precision seamless pipe   Generally, steel with carbon content ≤ 0.25% is called high carbon steel. The quenching mechanism of high carbon steel is metallographic structure and a small amount of ferrite. Its compressive strength and strength are low, and its plastic deformation and ductility are good, which is convenient for drawing and stamping. Die, extrusion, forging and ... Continue reading →

SSAW steel pipe is made by rolling low carbon carbon structural steel or low alloy structural steel strip at a certain helical angle (called forming angle) into a tube blank, and then welding the pipe seams. Steel produces large diameter pipes. Its specifications are expressed by outer diameter * wall thickness, and the welded pipe should ensure that the hydraulic test, the tensile strength of the weld and the cold bending performance meet the requirements. Length measurement method of ssaw steel pipe 1) Camera length measurement The camera length measurement is to use image processing to measure the length of the steel pipe. When the steel pipe passes through this area, the length of the steel pipe can be determined according to the position of a photoelectric switch on the screen where the image is captured by the camera.   The feature is that it can realize online measurement, and the length data can be obtained when the steel pipe passes through the length measurement area, ... Continue reading →