In which case, the steel pipe needs anti-corrosion treatment

　　There are three cases of steel pipe anti-corrosion treatment:

　　1) If it is used in a general warehouse or canopy or workshop, it is not required to be treated with antiseptic treatment;

　　2) If used in chemical workshops or in workshops or other structures with corrosive contact, anti-corrosion treatment is required;

　　3) There are special requirements for steel pipes;

　　The steel pipe anti-corrosion quota can be installed as follows

　　1, Enhance the adhesion of the topcoat to the substrate to prevent the coating from penetrating too much into the substrate.

　　2, anti-alkali. The enclosed base alkali penetrates into the coating to reduce erosion of the topcoat.

　　3, Anti-rust, to prevent the corrosion of the top paint after the iron products in the base layer are rusted. In addition, the use of a primer can also enhance the texture of the system, save the amount of topcoat and shorten the construction time. Direct construction without primer will affect the appearance and texture of the paint film, and may also cause problems such as chalking. Metal coating without primer can not achieve effective rust prevention.

Introduction of alloy steel tube

　　The alloy steel tube is mainly used for the heating surface tube of low and medium pressure boilers (the working pressure is generally not more than 5.88Mpa and the working temperature is below 450°C); it is used for high pressure boilers (the working pressure is generally above 9.8Mpa, and the working temperature is 450°C～650 °C), heating surface pipe, economizer, superheater, reheater, petrochemical industrial pipe, etc.

　　High-pressure alloy pipe grade: 15CrMoG, 12Cr2MoG, 12Cr1MoVG, 12Cr2MoWVTiB, 10Cr9Mo1VNb, SA210A1, SA210C, SA213 T11, SA213 T12, SA213 T22, SA213 T23, SA213 T91, SA213 T92, ST45.8/III, 15Mo3, 13CrMo44, 10CrMo910, etc.

　　1, Application

　　The main purpose of alloy steel pipe is used in high-pressure high-temperature pipelines and equipment such as power plants, nuclear power, high-pressure boilers, high-temperature superheaters and reheaters. It is made of high-quality carbon steel, alloy structural steel and stainless steel. It is formed by hot rolling (extrusion, expansion) or cold rolling (drawing).

　　2, Advantages

　　It can be 100% recycled, in line with the national strategy of environmental protection, energy saving and resource conservation. The national policy encourages the expansion of the application field of high-pressure alloy tubes. At present, China's alloy tube consumption accounts for half of the total amount of steel in developed countries, and the expansion of alloy tube use provides a broader space for industry development. According to the research of the expert group of the alloy pipe branch of China Special Steel Association, the demand for long-term high-pressure alloy pipe in China will increase by 10-12% annually.

　　3, Contact and difference with seamless pipes

　　The alloy pipe is defined by the production material (that is, the material). As the name suggests, it is the pipe made of alloy; and the seamless pipe is defined by the production process (seam seamless), which is different from the seamless pipe. There are seam pipes, including straight seam welded pipes and spiral welded pipes.

　　4, Standard

　　The alloy tube has a hollow section and is used as a conduit for transporting fluids, such as pipes for transporting petroleum, natural gas, gas, water, and certain solid materials. Compared with solid steel such as round steel, alloy steel pipe has light weight when the bending and torsional strength are the same. Alloy steel pipe is an economical section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe and automobile transmission. Shafts, bicycle frames, and steel scaffolding used in construction. The use of alloy steel pipe to manufacture ring parts can improve the material utilization rate, simplify the manufacturing process, save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., and have been widely used in steel pipes. Alloy steel pipes are also indispensable materials for various conventional weapons, and barrels, barrels, etc. are all made of steel pipes. Alloy steel pipes can be divided into round pipes and shaped pipes according to the shape of the cross-sectional area. Since the area of the circle is the largest under the condition of equal circumference, more fluid can be transported by the circular tube. In addition, the circular section is subjected to a relatively uniform force when subjected to internal or external radial pressure, and therefore, most of the steel pipes are round pipes.

What is a neck flange?Where is it used?

　　The neck flange, also known as the WN flange, has the primary function of joining two components into a given pipe system. Mounted in pairs, the contact between the two parts is guaranteed by the compression performed.

　　The neck flange was developed with the mission of transferring tension to the pipe. This transfer is intended to reduce the pressure at the base of the flange.

　　It can be used for any combination of pressure and temperature and furthermore, the neck flange attached to the pipe by a single butt weld gives lower residual stresses than the overlap type, for example. Assembly requires that the pipe be cut to the exact size and bevelled for the butt weld.

　　Other features of neck flange:

　　Tapered neck, above average strength, which prevents part deformation, beveled end, structure designed to withstand varying and high pressure and temperature, and weldability to the top of the flange.

　　And Prime Steel Pipe has the mission to offer the highest quality products at a fair price, able to meet the needs of its customers, achieving consistently better results, as its competence and talent are added to the technical capacity, experience and knowledge of the company. company to form a set of values that position it as a market leader.

Analysis of cracking reason on steel tube surface

　　Surface microcracks of lsaw steel pipe impact on product quality greatly, ranging from commuted, while in retirement, especially niobium, vanadium, titanium Longitudinal most prominent, has seriously affected the improvement of product quality and finished product rate. This not only gives the enterprise has brought huge economic losses, but also restricts the development of varieties of plate production line. Longitudinal surface microcracks mainly has edge crack, longitudinal, star cracks, its causes both improper rolling process parameter control, there are abnormal production of continuous casting process, the slab cracks genetic, residual element enrichment.

　　Longitudinal surface microcracks severely affect product quality. Longitudinal surface micro cracks main reason is the continuous casting mold copper coating off. This aspect will lead to copper penetration into the solidified shell austenite grain boundaries, grain boundary cracks; on the other hand will be uneven due to thermal stress cracks and crack sensitivity containing titanium steel strong performance is particularly evident . Control measures: To improve the quality of mold copper, copper to prevent dew; strengthen inspection before production of slab quality and production after Longitudinal; Longitudinal protection through good casting and other measures to improve Longitudinal steel cleanliness.

Prewelding process of LSAW steel tube

　　LSAW steel pipes (UOE, JCOE) manufacturing processes, welding processes are set to continuous advance. Its role is to be finalized after the tube forming, shaping and positioning within the weld seam on the back cover, in order to ensure the pipe dimensions and is conducive to tube welded pipe to improve quality and production efficiency.

　　Pre-welding process

　　After forming the tube by the next roller conveyor transported to a pre-welder's torch, rising rotating roll, rotate to adjust an open position to weld at the top of both sides of the pressure on the pressure roller and the pressure roller so that the tube seam, drop gun and adjust the tracking of the weld seam, open the protective gas and cooling water, start welding, welding condition monitoring, welded to the tube end welding arc stops (automatic delay stop gas), lift the gun and the top pressure rollers, pipe welder pre sent , pipe ends and welding defects.

　　Pre-welding process characteristics

　　Pre-welding using Ar + CO2 mixed gas shielded arc welding, continuous welding seam on the back of the tube to move at a faster speed. Since the bevel angle, tube shape, the tube along the longitudinal direction of the opening and both sides of the plate edge distortion factors of inequality, forming the seam after seam quality is not stable, larger changes. Need to change the tube seam welding, the arc of a steady state, the weld position deviated from the case and other real-time tracking and adjusted accordingly. Thus presoldered have welding speed, impact seam quality factors, changes and adjustments randomness and other characteristics.

Application of High Pressure Boiler Tube In Life

　　The rapid development of the national economy has led to the improvement of people's living standards, which have contributed to the development of the power industry. The power industry is environmentally viable and in line with our sustainable development strategy. According to China's resources, China is still dominated by thermal power at this stage and for a long time to come.

　　It is said that the electric power industry should mention high-pressure boiler tubes. The boiler tubes are steels that are open at both ends and have a hollow section. The steel with a relatively large length and the surrounding area can be divided into seamless steel pipes and welded steel pipes according to the production method. Dimensions (such as outer diameter or side length) and wall thickness indicate a wide range of sizes, from small diameter capillaries to large diameter pipes up to several meters in diameter. Steel pipes can be used in pipelines, thermal equipment, machinery industry, petroleum geological exploration, containers, chemical industry and special applications. In general, the high-pressure boiler tube is also a kind of seamless steel pipe, and its production process is the same as that of the seamless steel pipe. However, high-pressure boiler tubes are important components of power station boilers, used to manufacture high-pressure and ultra-high-pressure power station boilers, and are used to build large-scale thermal power plants.

　　Therefore, high-pressure boiler tubes are often in a high-temperature, high-pressure environment, so the requirements for his raw material billets are required. It is very strict and requires high durability and high corrosion resistance, oxidation resistance, and good stability.This will require you to shop around when you choose a high-pressure boiler tube, compare the price, but also to compare the quality.

　　http://www.xysteelpipe.com/info/Application-of-High-Pressure-Boiler-Tube-In-Life-1528-1.htm

Various factors affecting the hardenability of steel

　　Due to the high hardenability and strengthening the role of alloying elements, some high strength martensitic stainless steel, high speed tool steel and high-strength alloy steel. Often in the quench (or tempering) after a high-temperature tempering, the steel carbide appropriate aggregation obtain coarse carbide particles tempered sorbite organization (with ball annealing similar organizations) Thus, this delivery steel state has good cutting performance cooling directly after delivery, known as hot rolling or forging state, after hot rolling or forging steel and not subject to special heat treatment. Hot rolling (forging) termination temperature is generally 800-900 ℃, after the general natural cooling in the air, and thus hot rolling (forging) state corresponds to normalizing. Unlike strict normalizing heating temperature control, the difference because of hot-rolled (forging) termination temperature high and low. Thus it is well done microstructure and properties of the steel shaken ratio.

　　1. That many steel companies controlled rolling, since the finishing temperature control is very strict and forced cooling after finish rolling to take measures so that grain refinement of steel, delivery of steel with high mechanical properties. Since the appearance of the skin is covered with a layer of iron oxide, which has a certain degree of corrosion resistance, as stringent storage requirements are not kept cold drawn (rolled) state delivery of steel, medium-sized steel, thick steel plate can be in the open air yard or through thatch cover and store the non-twist and controlled cooling hot rod location is the truth, hot-rolled (forging) state of delivery than ordinary steel hot rod performance.

　　2. Cold drawn (rolled) on steel hardenability without any heat treatment and direct delivery, the status of the cold drawing, cold-rolled steel cold forming. Called cold-drawn or cold-rolled condition. Cold-drawn steel dimensions (rolled) state of high accuracy, good surface quality, appearance roughness is low, and have high mechanical properties, compared with the hot rolling (forging) state. Since the cold drawn (rolled) state of delivery without scale steel outer cover, and there is a big stress, vulnerable to corrosion or rust, and thus cold drawn (rolled) state steel, packaging, storage and transportation are more stringent requirements, generally need to be in the custody of the Treasury, and the Treasury should pay attention to the temperature and humidity control the delivery state within the state, said normalizing. Since normalizing heating temperature (hypoeutectoid steel as Ac3 + 3050 ° C eutectoid steel as Accm + 3050 ° C than hot-end temperature control strict.

　　3. Before normalizing the status of the steel factory and normalizing heat treatment. Thus the structure of the steel, a uniform performance. Since normalizing cooling faster, compared to steel annealed state. Pearlite structure of the steel increased number of pearlite lamellar and grain refinement of steel, and thus have higher mechanical properties, and help to improve the low carbon steel widmanstatten and eutectoid steel cementite net, for further heat treatment of the finished product do organizational readiness.

Low carbon steel welding process

　　Low carbon steel has a carbon content of ≤0.25%, and its plasticity is good. Generally, it has no tendency to harden, is not sensitive to the welding process, and has good weldability. When welding such steels, special process measures are not required, and heat treatment (except electroslag welding) is usually not required after welding.

　　For low-carbon steel structures with a thickness greater than 50 mm, high-current multi-layer welding is commonly used, and internal stress annealing is eliminated after welding. When the structure with high welding rigidity in a low temperature environment is large, the temperature difference between the parts of the weldment is large, and the deformation is limited. The welding process is prone to generate large internal stress, which may cause cracking of the structure. Therefore, preheating before welding should be performed.

　　Low carbon steel can be welded by various welding methods, and the most widely used are electrode arc welding, submerged arc welding, electroslag welding, gas shielded welding and electric resistance welding.

　　When welding structural steel by fusion welding, the selection of welding materials and processes should mainly ensure the strength of welded joints and workpiece materials. Welding rod arc welding is generally low carbon steel structure, E4313 (J421), E4303 (J422), E4320 (J424) welding rod can be selected. When welding dynamic load structures and complex structures, E4316 (J426), E4315 (J427) or E5015 (J507) electrodes should be used. For submerged arc welding, H08A or H08MnA welding wire with flux 431 is generally used for welding.

Anti-corrosion and heat preservation performance of spiral steel tube

　　Anti-corrosion insulation pipe with corrosion resistance of steel, and has good insulation properties, has been widely used and promoted in building construction, and constantly improve and spread. Corrosion pipe insulation having different processing types and methods, different processing method to determine the pipe have different properties and functions, and the use range also changes. As the name suggests, it is to increase the number of external spiral steel pipe corrosion insulation class protection, in order to achieve low temperature can be used. In general, the use of second degree pipe insulation inorganic zinc-rich paint, which temperature ≥400 ℃, belonging to corrosion coating, conduit port is used polyethylene film called 3-layer PE or using cold sealing tapes to achieve the previously installed to prevent moisture entering into the water or construction.

　　Spiral steel pipe insulation for high temperature, water and fuel pumps, chemical pump corrosive. Insulation pipeline centrifugal pump series products with low noise, performance, energy efficient and reliable. The insulation material used is a multi-layer bandaging wrong seam, so it is effective to reduce the heat loss, but also able to control the jacket surface measures to prevent the generation of cold bridges, so that the outer coating of temperature control is guaranteed. Spiral steel pipe wrapped with insulation material multilayer reflective layer of aluminum foil, which can effectively reduce the loss of heat, and can make the steam pipe can be more economical and reasonable. Anti-corrosion steel pipe insulation is a good corrosion resistance, along with good insulation properties, has been widely used and promoted in the design and construction, the current and constantly perfected and popularized. Spiral steel also have different types and methods of processing, while the different processing method to determine the pipe have different properties and functions, and range will change!

Method for Distinguishing the Quality of Seamless Steel Pipes

　　The use of seamless steel pipes is becoming wider and wider. When we choose seamless steel pipes, we must test the quality of seamless steel pipes. The following small series is detailed for everyone:

　　1. The fake and inferior seamless steel pipe is easy to be scratched, because the equipment of the fake and inferior seamless steel pipe manufacturers is simple, easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.

　　2. The counterfeit seamless steel pipe has no metallic luster and is light red or similar to pig iron.

　　3. The cross-fabricity of the counterfeit seamless steel pipe is thin and low, and the phenomenon of filling and dissatisfaction often occurs. The reason is that the manufacturer has to achieve a large negative tolerance, and the reduction of the first few passes of the finished product is too large, the iron type is small, and the hole type is not full.

　　4. The cross-section of the counterfeit semanufacturer has to reduce the amount of the two rolls in front of the finished roll in order to save material. The strength of this seamless steel pipe is greatly reduced, and it does not conform to the seamless steel pipe. The standard of the dimensions.

　　5. The composition of high-quality seamless steel pipe is uniform, the tonnage of the cold-shearing machine is high, the end face of the cutting head is smooth and tidy, and the surface of the inferior seamless steel pipe is often poor due to poor material, and the end face of the cutting head often has a phenomenon of falling meat, that is, unevenness, and no Metallic luster. And because the fake and inferior manufacturers have fewer heads, big ears will appear at the head and tail.

　　6. The fake and inferior seamless steel pipe material contains many impurities, the density of the steel is small, and the size is too bad, so in the absence of the vernier caliper, it can be weighed and checked. In general, the whole box weighing effect will be better, mainly considering the problem of cumulative error and probability theory.

　　http://www.xysteelpipe.com/info/Method-for-Distinguishing-the-Quality-of-Seamless-Steel-Pipes-1520-1.htm