Xinyue leads fresher to successfully signed the first orders

Project location：Thailand

Product：LSAW steel pipe

Standard and material：EN10219 S355JR

Specifications：800*30*5000mm;800*30*6750mm

Application：Stock use

Arrival time：2023.10

We received an inquiry from a new customer in Singapore on 11th August. After less than a month of close follow-up, we reached an agreement with this customer on 4th September. This is Jasmine’s first order after joining Xinyue as a fresher. During the communication and negotiation process, she paid close attention to all customer needs, answered questions and made proposals in real time. The whole cooperation process was quite pleasant. The customer visited our factory and inspect the goods on his own. Without any doubt, the entire batch of goods passed the customer’s quality inspection. It was shipped by end of September and arrived at the customer’s warehouse at the end of October. Customers expressed high recognition of Xinyue’s comprehensive strength, especially the quality control system, laying a solid foundation for subsequent in-depth cooperation.

Xinyue has always been taking “To promote steel industry, To represent Made- in-China” as its mission, taking every order seriously and completing every order perfectly. Step by step, Xinyue has been deeply cultivating and growing in the steel industry. Under the leadership of Xinyue Group, all Xinyue members are working hard unremittingly, growing in achievements and gains. We firmly believe that Xinyue’s future will be more brilliant.

https://www.xysteelpipe.com/xinyue-leads-fresher-to-successfully-signed-the-first-orders/

ERW and LSAW steel pipe delver to Indonesia

 Project location：Indonesia

Product：ERW/LSAW steel pipe, Unequal angle

Standard and material：EN10219-1 S355J0H, S355J2H; GB /T 3091 Q345B, EN10056 S275JR

Specifications：DIA:219.1-762mm, WT: 8-12.7mm Length: 11.9-12M

Application： Structural Usage

Shipping time：2023-06-16

With strong resource integration ability and the influence of Xinyue brand in Indonesia market, we successfully established the first cooperation relationship with this customer!

In just 20 days, after we inventoried the stock and submitted the MTC sample to the customer for material review, we successfully passed the SGS third-party inspection and physical and chemical test, and have successfully shipped the products.

The customer requested a wide range of products for this order, but the quantity of each product was small. How to gather the inventory quickly, how to ensure the material audit passed smoothly, and how to ensure the quality of the products, etc. This is exactly where our company has the advantage, and with our ability to integrate resources and rich experience, we were able to successfully solve these problems.

First of all, our company has an extensive supply chain network and stable partners in Tianjin. By working closely with various suppliers, we are able to quickly mobilize inventory of a wide range of products to ensure that orders are fulfilled on time. At the same time, we also negotiate and submit MTC samples with our customers in order to audit the conformity of the materials. Our company strictly adheres to international standards and quality requirements to ensure that the products supplied meet the expectations of our customers.

Secondly, we arrange our own inspection and laboratory to do the testing before the final inspection and physical and chemical performance testing by the SGS third-party organization commissioned by the customer. This initiative can not only ensure the quality and conformity of the products, but also increase the trust of customers and ensure the quality of goods without worries.

Finally, we shipped the goods to Tj Priok terminal in Indonesia without any problems, providing efficient logistics services to our customers. We worked with a reliable logistics partner to ensure the cargo was routed on a direct route and to provide timely tracking and communication when needed. This efficient logistics solution provides customer convenience, reduces transit time and costs, and increases customer satisfaction.

Our ability to provide quick solutions to a wide range of product requirements and our extensive experience enable us to meet our customers’ needs.

https://www.xysteelpipe.com/erw-and-lsaw-steel-pipe-delver-to-indonesia/

A brief Introduction of Xinyue’s LSAW Steel pipe

Xinyue’s LSAW steel pipe is one of the most reliable and cost-effective solutions for various industrial applications. As a leading manufacturer of LSAW steel pipes in China, Xinyue Steel has a proven track record of delivering high-quality products to customers worldwide. In this article, we will introduce the benefits of Xinyue’s LSAW steel pipes and provide a guide for customers to buy our products.

Firstly, Xinyue’s LSAW steel pipes are made of high-quality steel and are widely used in the oil and gas industry, chemical industry, and other industrial sectors. These pipes are known for their durability, strength, and resistance to corrosion, making them the ideal solution for demanding applications.

Secondly, Xinyue’s LSAW steel pipes come in a variety of sizes and shapes to fit any industrial need. Our pipes are available in diameters ranging from 219.1mm to 1820mm, with thicknesses of up to 50mm. With a maximum length of up to 70 meters, our pipes can be customized to meet specific project requirements.

Thirdly, Xinyue Steel’s LSAW steel pipes are manufactured using advanced production technology and strict quality control processes. We use only the highest quality raw materials, and our production processes are carefully monitored to ensure that our products meet the strictest industry standards. Our pipes undergo rigorous testing to ensure that they meet the required performance specifications and that they are free from defects.

If you are looking to buy LSAW steel pipes, here is a step-by-step guide on how to purchase Xinyue’s products:

Determine your project requirements, such as pipe diameter, wall thickness, and length.

Contact Xinyue Steel and provide us with your project requirements. Our sales team will provide you with a quotation and answer any questions you may have.

Review the quotation and confirm the order with Xinyue Steel.

Our team will manufacture the pipes and perform quality control checks to ensure that they meet the required standards.

Once the pipes have been manufactured and have passed our quality control tests, we will arrange for shipping and delivery to your project site.

https://www.xysteelpipe.com/a-brief-introduction-of-xinyues-lsaw-steel-pipe/

Precautions for transportation of large diameter thin wall LSAW steel pipe

 　　Because of the large diameter and thin wall thickness of large-diameter thin-walled LSAW steel pipes, special attention must be paid during transportation. When transporting large-diameter thin-walled straight seam steel pipes, short pipes should be used as support frames in the steel pipes in the form of crosses to prevent deformation. Large-caliber thin-walled straight seam steel pipes generally can only be installed in a carriage 1 to 2 pipes, and wooden bricks should be used at the bottom to pad both sides to avoid rolling and deformation.

　　In addition to preventing rainwater from being exposed to large-diameter thin-walled LSAW steel pipes during transportation, the driver must pay attention to the weather at all times and also pay attention not to touch corrosive chemicals.

　　The characteristics of the use of large-diameter straight seam steel pipes in steel structure engineering:

　　Steel structure straight seam steel pipes can be divided into high-frequency straight seam steel pipes (ERW pipe) and submerged arc welded straight seam steel pipes according to the production process. Submerged arc welded straight seam steel pipes are divided into UOE, RBE, JCOE steel pipes, etc. according to their different forming methods. Thick-walled straight seam steel pipe, the steel pipe with the ratio of the outer diameter of the steel pipe to the wall thickness of less than 20 is called the thick-walled straight seam steel pipe. Mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes and high-precision structural pipes for automobiles, tractors, etc.

　　The difference between thick-walled straight seam steel pipe and thin-walled straight seam steel pipe is the thickness of the steel pipe wall. It is generally believed that wall thickness/pipe diameter equal to 0.02 is the watershed between thick-walled straight seam steel pipe and thin-walled straight seam steel pipe, and the wall thickness/pipe diameter is less than 0.02 The thin-walled steel pipe is larger than the thick-walled straight seam steel pipe. In terms of application, thin-walled steel pipe is mostly used for pipelines.

　　http://www.xysteelpipe.com/info/Precautions-for-transportation-of-large-diameter-thin-wall-LSAW-steel-pipe-1965-1.htm

ERW, SSAW, LSAW welded steel tube

    ERW steel pipe: high-frequency straight seam resistance welded pipe, using hot-rolled wide coil as the material, through pre-bending, continuous forming, welding, heat treatment, sizing, straightening, blocking and other processes, it has a shorter weld seam than the spiral, standard High precision, uniform wall thickness, good surface quality, and high-end benefits under pressure, but the defect is that only small and medium-diameter thin-walled pipes can be produced, and the welds are prone to gray spots, unfused, and groove-shaped corrosion defects. At present, the widely used fields are city gas, crude oil products and oil transportation, etc.

    SSAW steel pipe: spiral submerged arc welded pipe, which has a forming angle (adjustable) with the center line of the forming pipe when the pipe is rolled, and is welded while forming, and its welding seam is formed into a spiral line, and the same standard can produce a variety of diameters Standard steel pipe, the material is used to planning larger, the weld can avoid the main stress, the stress is better, the defect is a few standards are poor, the length of the weld is longer than that of the straight pipe, the crack is easy to crack, the slag is included, the welding deviation, etc. Welding defects, welding stress is tensile stress. The general design rules and regulations of long-distance spiral submerged arc for oil and gas pipelines can only be used in category 3 and category 4 areas.

    LSAW steel pipe: Straight seam submerged arc welded pipe, which is made of a single medium-thick plate by pressing (rolling) the steel plate in a mold or forming machine, using double-sided submerged arc welding and expanding the diameter to produce. Its product standard planning is wide, and the resistance, plasticity, uniformity and fineness of the weld are good. It has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. When creating high-strength, high-endurance, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-diameter thick-walled straight-seam submerged arcs. According to API standard rules, in large oil and gas transportation pipelines, when passing through Class 1 and Class 2 areas such as the seabed in high cold areas and densely populated urban areas, the straight-seam submerged arc is the only designated pipe type.

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.

Quality problem of LSAW steel tube

　　In the LSAW steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process.

　　The heat with the furnace, according to their results, and reheating furnace is divided into two kinds; the former is used to billet heated from room temperature to the processing temperature; the latter is used in the process in the blank reheated to the required processing temperature.

　　Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason.

　　Furnace There are many ways, but the primary use is a ring furnace. This furnace has an annular hearth, it can slowly change the direction of the diameter of the blank along the bottom of the load from the entrance, a reversal can be used at the outlet of the heating and soaking temperature to the rule kind of stove. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate.

Professional Skills of Straight Seam Double Submerged Arc Welded Steel Pipe

　　Professional skills of straight seam double submerged arc welded steel pipe(lsaw steel pipe) are following below:

　　1, Double submerged arc welding method in a new invention in 1940, in front of it and the manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating. Straight seam double submerged arc welding and manual welding the same place that it still uses residue protection, but this is not the dregs electrode coating, specifically melting out of the flux. Flux The flux system consists of a funnel filled through a pipeline to be welded to the front.

　　2. The second difference is the use of electrode using wire, because wire can be continuously sent; electrodes, we burn a welding electrode must have a head gave threw it, and the operation had to stop, and then change the electrode welding.

　　3. In this way, the first advantage is fully automated; second advantage, which is under the submerged arc welding, so its heat exchange and protection of relatively strong performance, high quality weld out; third advantage, since the automatic submerged arc welding arc buried under welding flux, so it can use high-current, high welding efficiency, the recent progress of our country natural gas pipeline project.

　　4, Later changed to the wire, with the wire feed unit and wire spool is continuously sent to the wire, the welding wire is continuously fed, igniting an arc in the meltable particulate flux covering, welding wire, part of the melting and evaporation of the base metal and solder forms a cavity, the arc is stabilized combustion cavity inside, so call it submerged arc welding. Arc is buried in the inside of the cavity.

　　5, The pipe is a high-strength steel, such pipelines in the factory inside the first preformed section, and then get on the site, in the field of welding, the welding process such pipelines in factory production is the use of submerged arc welding, now buried welding has developed into, a double wire submerged arc welding, as well as multi-wire submerged arc welding, to further improve efficiency.

Welding quality control measures of LSAW steel pipe

　　Large diameter LSAW steel pipe with its big wall thickness, good material, stable processing technology, becomes the preferred pipe by largest domestic and foreign oil and gas transportation project. In the large diameter LSAW steel pipe welded joints, weld and heat affected zone are the most prone to produce a variety of defects, and welding undercut, pores, slag, not fused, not penetration, welding cracks are the main form of welding defects, and also are the origins those often make LSAW steel pipe produce quality accident. The quality control measures will be listed below, if you you are interested in the production process of LSAW steel pipe, you can click the hyper-link.

　　1.The quality control before welding:

　　1) First of all, pipe manufacturer should take control of the quality of raw materials, after passing the inspection, raw materials can formally enter the construction site. And pipe manufacturer resolutely put an end to the use of substandard steel.

　　2) The next is the management of the welding material. Checking whether the welding material is a qualified product, whether storage and baking system is implemented, whether the surface of the welding material is clean and no rust, and whether the electrode coating is intact, with mildew or not.

　　3) The next is the welding area cleaning management. Check the cleaning quality of the welding area, there shall not be water, oil, rust and oxide film and other dirt, which plays an important role to prevent the occurrence of external defects in the weld.

　　4) Finally, choosing the appropriate welding method, it should be implemented before the test welding, after welding principle.

　　2. The quality control during welding:

　　1) According to the welding process to review the specifications of the wire and flux is correct or isn't, to prevent the wrong welding wire and flux caused by welding quality accidents.

　　2) Monitor the welding environment, when the welding environment is not good (temperature below 0 ℃, relative humidity greater than 90%) pipe manufacturer should take appropriate measures after welding.

　　3) Checkout the groove size, including the gap, blunt edge, angle and wrong, etc. meet the process requirements or not before pre-welding.

　　4) Checkout the selected welding current, welding voltage, welding speed and other process parameters are correct or aren't in the submerged arc internal and external welding process.

　　5) Supervise the welding personnel in the submerged arc internal and external welding full use of the length of the pipe end of the arc plate to strengthen the internal and external welding arc plate use efficiency, which helps to improve the quality of pipe end welding.

　　6) Supervise the welding staff in the welding is the first clean up the slag, whether it has been completely handle joints, groove whether there is oil, rust, slag, water, paint and other dirt.

LSAW steel pipe production process

　　LSAW steel pipe is a longitudinally parallel steel pipe. Usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. The straight seam welded pipe has a simple production process, high production efficiency, low cost, and rapid development. LSAW steel pipe according to the production process can be divided into high-frequency straight seam steel pipe and submerged arc welded straight seam steel pipe. Submerged arc welded straight seam steel pipes are divided into UOE, RBE, and JCOE steel pipes according to their different forming methods. The following describes the most common high-frequency straight seam steel pipe and submerged arc welded straight seam steel pipe forming process.

　　1. Striking: After the steel plate used for manufacturing large-diameter submerged-arc welded straight-joint steel pipes enters the production line, full-plate ultrasonic inspection is first performed;

　　2. Milling edge: Through the edge milling machine, the two edges of the steel plate are double-sided milled to achieve the required plate width, plate edge parallelism and groove shape;

　　3. Pre-bend: Pre-bending machine for pre-bending the edge so that the edge of the board has a curvature that meets the requirements;

　　4. Forming: Firstly, half of the pre-bent steel plate is stamped and stamped into a "J" shape on a JCO forming machine. The other half of the steel plate is also bent and pressed into a "C" shape to form an opening. The "O" shape

　　5. Pre-welding: After the formation of straight seam welded steel pipe joints and continuous welding using gas shielded welding (MAG);

　　6. Internal welding: Use vertical multi-wire submerged arc welding (up to four wires) to weld inside the straight seam steel pipe;

　　7. Outer welding: Use vertical multi-wire submerged arc welding to weld outside LSAW steel pipe;

　　8. Ultrasonic inspection I: 100% inspection of the internal and external welds of the longitudinal welded steel pipe and the base metal on both sides of the weld;

　　9. X-ray inspection I: 100% X-ray industrial television inspection of the inner and outer welds, using image processing systems to ensure the detection sensitivity;

　　10. Expanded diameter: The full-length of the submerged-arc welded straight seam steel pipe is expanded to improve the dimensional accuracy of the steel pipe, and the distribution of the internal stress of the steel pipe is improved;

　　11. Hydraulic pressure test: The root diameter of the expanded steel pipe is tested on the hydrostatic testing machine to ensure that the steel pipe meets the required test pressure. The machine has automatic recording and storage functions;

　　12. Chamfering: After passing the inspection, the steel pipe is processed by the pipe end to reach the required pipe end groove size;

　　13. Ultrasonic inspection II: Ultrasonic inspection is performed one by one again to check for defects that may occur in straight seam welded steel pipes after diameter expansion and water pressure.

　　14. X-ray examination II: X-ray industrial television inspection and tube-end weld seam examination of steel tubes after diameter expansion and hydrostatic pressure testing;

　　15. Tube end magnetic particle inspection: This inspection is performed to find the tube end defects;

　　16. Anti-corrosion and coating: The qualified steel pipe is anti-corrosion and coating according to the user's requirements.

LSAW Steel Pipe vs SSAW Steel Pipe

　　1, Difference between lsaw steel pipe and ssaw steel pipe in production process

　　LSAW steel pipe is a longitudinally parallel steel pipe. Usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. The straight seam welded pipe has a simple production process, high production efficiency, low cost, and rapid development. SSAW steel pipe is a coiled steel pipe made from strip coils as the raw material, which is often warm extruded and welded by an automatic double wire double-sided submerged arc welding process.

　　The strength of the ssaw steel pipe is generally higher than that of the lsaw steel pipe. A narrower blank can be used to produce a larger diameter pipe, and a blank having a different diameter can be produced from a blank of the same width. During the forming process, the steel plate is uniformly deformed, the residual stress is small, and the surface is free of scratches. The processed spiral steel pipe has greater flexibility in the range of diameters and wall thicknesses, especially in the production of high-grade thick-walled pipes, especially small- and medium-caliber thick-walled pipes, which have unparalleled advantages over other technologies and can satisfy users. More requirements on the specifications of spiral steel pipe. The use of advanced double-sided submerged arc welding technology can achieve welding in the best position. It is not prone to defects such as misalignment, welding deviation and incomplete penetration, and it is easy to control the welding quality. However, compared with the straight seam pipe of the same length, the length of the weld seam increases by 30 to 100%, and the production speed is low.

　　2, Difference between lsaw steel pipe and ssaw steel pipe in security analysis

　　LSAW steel pipe is mainly subjected to residual stress caused by inhomogeneous cooling. Residual stress is the stress of internal self-phase equilibrium under no external force. Hot rolled section steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress is. Although the residual stress is self-balanced, it still has certain influence on the performance of steel components under external forces. For example, it may have adverse effects on deformation, stability, and fatigue resistance; after welding, The non-metallic inclusions inside the straight seam steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination weakens the performance of the straight seam steel pipe in the thickness direction, and there is a possibility of interlayer tearing when the weld seam shrinks. The local strain induced by weld shrinkage often reaches several times of the yield point strain, which is much larger than the strain caused by the load. In addition, the lsaw steel pipe will inevitably have many T-welds, so the probability of welding defects is also greatly improved. Moreover, the welding residual stress at the T-weld is large, and the weld metal is often in a three-dimensional stress state, increasing the possibility of cracking.

　　SSAW steel pipe with spiral weld distribution, long weld, especially in the dynamic conditions of welding, the weld is too late to leave the molding point of cooling, easy to produce welding hot cracks. The direction of the crack is parallel to the weld and is at a certain angle to the axis of the steel tube, typically between 30-70°. This angle is just in line with the shear failure angle, so its bending, tensile, compressive and torsional resistance is far inferior to the LSAW pipe. At the same time, due to the limitation of the welding position, the resulting saddle shape and ridge-shaped welding seam influence Beautiful. In addition, during the construction process, the intersecting line welds at the spiral welded parent pipe joints split the spiral joints and generate larger welding stress, which greatly weakens the safety performance of the components. Therefore, the non-destructive testing of the spiral welded pipe joints should be strengthened. Ensure welding quality, otherwise spiral submerged arc welded pipe should not be used in important steel structure occasions.

　　3, Difference between lsaw steel pipe and ssaw steel pipe in the scope of application

　　LSAW pipe adopts double-side submerged arc welding process. Welding under static conditions, the quality of the weld is high, the weld is short, and the probability of defects is very small. The steel pipe expands through full-length, has a good pipe shape, and is precise in size. The steel pipe has a wide wall thickness range and a wide range of pipe diameters. It is suitable for supporting columns, ultra-large span building structures, such as buildings, bridges, dams, and offshore platforms, as well as wind-resistant and earthquake-resistant structures. Pole mast structure. Spiral steel pipe is a kind of steel commonly used in industry, construction and other industries. Mainly used in tap water projects, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction.

　　In summary, we can see that the two different types of welded seam pipes have their own characteristics and have different advantages according to different applications.

The Application Range of LSAW Steel Pipe

　　LSAW (LSAW-Longitudinal Submerged Arc Welded) was invented in 1940, a new welding method, welding hand in front of it and the same place it is to protect the use of slag, but this residue is not a skin electrode medicine . Straight seam double submerged arc welding and manual welding the same place it is to protect the use of slag, but this residue is not a skin electrode medicine, is dedicated melting out of the welding flux. The welding system consists of a funnel drug loading of the welding flux through a pipeline to be welded to the front. The second difference is the use of welding, using wire, because the wire can be continuously sent; electrode, we gotta burn a welding electrode head and gave a throw, and the operation was stopped, for welding and then welded.

　　The application range :

　　LSAW steel pipe diameter in the range between 406 ~ 1600mm, in exceptional cases even more, the ratio of wall thickness and diameter of about 0.06 to 0.08. Modern foreign technology can produce pipe up to 100mm wall thickness of pipe.

　　Industrial production of steel plate or straight seam steel pipe only a few ways, the principle difference is the method of forming steel pipe, steel pipe after forming the follow-up process is basically the same. Methodological principles of forming the weld depends on the distribution of steel, according to the distribution of the pipes to weld two basic forms: straight seam and spiral seam steel pipe. Corresponding to this, straight seam welded pipe production into the production and the production of spiral seam pipe. Straight seam and spiral seam steel pipe the most widely used method is submerged arc welding (SAW), its good quality, high productivity, technology is mature and stable. Currently, straight seam steel pipe widely used abroad following range: air land and sea transport, water and oil trunk pipelines; transport chemicals and chemical products of stainless steel tube; marine industrial structure with a tube; boiler manufacturing and special purpose pipe structural tube.

Quality control method of LSAW steel pipe

　　Large diameter LSAW steel pipe with its large wall thickness, good material, processing technology and stability, has become the first choice of steel large oil and gas transmission project at present at home and abroad. LSAW steel pipe in large diameter welded joints, the weld and heat affected zone is the most easy to produce all kinds of defects, and welding undercut, porosity, slag inclusion, incomplete fusion, lack of penetration, overip, burn, welding crack is the main form of welding defects, it is often the origin of the LSAW steel pipe the quality accident.

　　Quality control measures:

　　1. 1) before the welding quality control to quality first good raw materials, can be officially entered the construction site after passing inspection, and resolutely put an end to the use of substandard steel.

　　2) followed by the management of welding materials. Check whether the welding materials for qualified products, storage and baking system is executed, issued by the welding material surface is clean without rust, the electrode is intact, there is no mildew.

　　3) again is the welding area clean management. Check the welding area clean quality, no water, oil, rust and other dirt film, which plays an important role in avoiding weld external defects.

　　4) select the appropriate welding methods, welding principle should be applied, after the implementation of welding test.

　　2. 1) quality control in welding according to welding procedure review of welding wire and flux specifications are correct, to prevent misuse of wire and flux caused by welding quality accident.

　　2) to supervise the welding environment, welding environment is not good (when the temperature is below 0 DEG C, the relative humidity is greater than 90%) to take corresponding measures after welding at.

　　3) to test the pre groove size before welding, including clearance, edge, angle and the wrong port meets the technical requirements.

　　4) used in the welding process and automatic submerged arc welding current, welding voltage, welding speed and other parameters are correct.

　　5) supervision personnel in the submerged arc welding automatic welding and make full use of the pipe end arc plate length, and enhance the efficiency of the use of welding arc plate, which helps to improve the welding quality of tube end.

　　6) personnel in the supervision of welding repair welding is clean, whether the first slag has been completely processing joint, whether there is oil, rust, slag, water, paint and dirt groove.

The Damaged Form of LSAW Steel Pipe Surface

　　LSAW steel pipe is formed by the surface layer of very thin and strong stability of fine chromium-rich oxide film (protective film), to prevent the continued infiltration of oxygen atoms, to oxidation, and access to anti-corrosion ability. If there is some reason, this film was the constant destruction, air or liquid oxygen or metal atoms will continue to penetrate the iron atom out from the constant analysis of the formation of loose iron oxide, metal surface corrosion will be constantly . This surface film in the form of a lot of damage, more common in everyday life are summarized as follows:

　　1. LSAW steel pipe surface deposit product with other metals containing dust particles or heterogeneous metal fixtures in the humid air, and stainless steel fixtures between the condensate, the two together into a micro-battery, causing the electric chemical reactions, protective film is damaged, call it that electrochemical corrosion.

　　2. Straight pipe surface adhesion organic juice (such as vegetables, soup, sputum, etc.), oxygen in the water case, constitutes organic acids, organic acids long is the corrosion of metal surfaces.

　　3. LSAW steel pipe surface adhesion with acid, alkali, salts (such as a wall decoration lye, lime splash), causing localized corrosion.

　　4. In a polluted air (which contain a large number of sulfide, carbon dioxide, nitrogen oxide atmosphere), the case of condensed water to form sulfuric acid, nitric acid, acetic acid solution point, cause chemical corrosion.

The effect of cold expansion on LSAW steel pipe

　　The effect of cold expansion on LSAW steel pipe:

　　(1) Improve the geometrical dimensional accuracy of the pipe body and pipe end of the lsaw steel pipe, so that the diameter and roundness of the pipe body and the pipe end and the diameter difference between the two ends of the steel pipe meet the standard requirements, which is convenient for on-site welding construction.

　　(2) Conduct a comprehensive and effective inspection of the overall performance of the steel pipe.

　　(3) Reducing the uneven deformation of the forming and welding process of lsaw steel pipe, reducing the residual stress of the pipe body caused by molding and welding, improving the distribution and improving the overall mechanical properties of the steel pipe.

　　(4) The cold expansion diameter also has the effect of improving the straightness of lsaw steel pipe, especially the straightening effect on the smaller diameter straight seam submerged arc welded pipe.

　　After the cold expansion of the lsaw steel pipe, the diameter of the pipe body and the pipe end will increase by about one percent. The diameter, the roundness and the diameter difference between the two ends of the steel pipe are greatly improved, and the straightness of the steel pipe is also greatly improved. The length is reduced by about 0.5%, and the wall thickness is reduced by about 0.8%. In the development of the lsaw steel pipe process, these changes should be fully considered to determine the width, length and thickness of the pipe sheet and the outer diameter of the steel pipe before the diameter expansion, so as to avoid the geometrical dimension of the steel pipe after the expansion is not up to the final requirements.

　　http://www.xysteelpipe.com/info/The-effect-of-cold-expansion-on-LSAW-steel-pipe-1202-1.htm

Select of Straight Seam Submerged Arc Welded Steel Pipe

　　(1) For high peak load requirements of the pipeline, because the user's gas consumption is very uneven, pipeline pressure fluctuations in the frequent, alternating stress steel to withstand large tubing will expand the existing defects in alternating stress, if more choice weld defects high probability of spiral welded steel pipe, the safe operation of the pipeline will not be guaranteed.

　　(2) Pipeline crossing earthquake fault or by topical highly seismic region, due to the geological activity of these lots frequent pipeline will have a vertical or axial alternating stresses. Spiral weld much higher than the probability of defect LSAW steel pipe, under long-term stress, spiral welded steel pipe is much higher than the probability of an accident LSAW steel pipe, therefore, in such areas should be used straight submerged arc welded pipe.

　　(3) Internal and external coating requires a high piping should be used LSAW. Spiral submerged arc welded pipe weld more general than the weld reinforcement LSAW high, when the steel pipe internal and external corrosion, anti-corrosion materials and combination of the bare tube is not as close LSAW, anticorrosive effect is not good LSAW steel pipe.

　　(4) For important wear across the engineering, use LSAW. Due to difficulties in future maintenance and management than the general line segment, therefore, the use of excellent performance LSAW particularly necessary.

　　(5) For the pipeline weaknesses, such as heat and simmer elbow pipe should be used LSAW. Heat simmer elbow since the direction of change, their exposure to internal and external forces than the general line of straight pipe should be large, due to the impact of various factors in the simmering process, it is not easy to eliminate stress, is a long-distance pipeline in the weak link , integrated performance good LSAW can make up for these deficiencies.

Thick Wall LSAW Steel Pipe Rust Oil

　　Thick-walled lsaw steel pipe anti-rust oil to be disposed of, we must first understand the characteristics and varieties of anti-rust oil, as well as their results. So this time in the procurement of goods can not be thrown off balance, direct save time. Below let us Xiaobian to introduce walled Longitudinal creosote strengths and varieties of it.

　　1. Quick-drying

　　Its biggest advantage of doing that is fast, rugged, use widely anticipated, it is possible to use in harsh environments, the use.

　　2. Soft membrane

　　With paraffin oil or heavy oil disposal made, rust-proof function are the three strongest presence, and can be washed using one kind of solvent.

　　3. Film type

　　Its anti-rust function relatively handicap. But its operation is very simple disposal. Use can reduce the harm caused by their conflict, reduce costs, ensure productivity directly carried out.

Thermal Deformation Method of LSAW Steel Pipe

　　First, reasonable selection. Precision messy mold material should choose a good micro-deformation of steel on steel carbide segregation serious mold should be a reasonable casting and heat treatment quenching and tempering, solution heat treatment on a large double refining and casting mold steel can not be carried out. Reasonable choice of heating temperature control heating rate, on messy precision molds can be heated slowly, preheating and other methods to reduce the mold uniform heating heat deformation

　　Second, the correct operation of the heat treatment process and reasonable heat treatment process is also a useful way to reduce messy precision mold deformation. Deformation reason messy precision molds are often messy, but we only need to master the rules of the deformation, to analyze the attack reason, the choice of methods to avoid abnormal deformation of the mold can be reduced, and also can be controlled.

　　Third, precision molds to be messy pre-heat treatment, machining process to eliminate the remaining episodes of stress. Precision messy mold, when conditions allow, try to use cryogenic vacuum heating process and hardening after quenching. Mold hardness in ensuring the premise, try to use pre-cooling, grading cooling or quenching temperature quenching process.

　　Fourth, mold planning is depicted to be reasonable, not too poor thickness, shape to be symmetrical with respect to large deformation mold deformation to master the rules, set aside allowance, on large, sophisticated planning messy mold can be used in combination. For some messy precision molds can be used pre-heat treatment, aging heat treatment, quenching and nitriding to control the accuracy of the mold. When mold repair blisters, porosity, wear and other defects, selection of cold welding and other small heat-affected patch repair equipment, to prevent deformation during the attack.

Weld treatment of LSAW steel pipe

    LSAW steel pipe is the strip into the pipe unit, the multi-roll rolling, strip gradually rolled up to form a circular gap open billet, adjust the squeeze roll reduction, so that weld gap control In the 1 ~ 3mm, and make both ends of the welding flush. If the gap is too large, it will reduce the proximity effect, eddy current heat shortage, weld intergranular bonding caused by poor fusion or cracking. Such as between

    If the gap is too small, the proximity effect will be increased, the welding heat will be too large, and the weld will be burned; or the weld will be crushed and crushed to form the pit, which will affect the weld surface quality.

    Welding process example:

    Weld φ32 × 2mm longitudinal welded pipe, for example, briefly describes the process parameters:

    Strip specifications: 2 × 98mm bandwidth by medium diameter expansion plus a small amount of molding margin.

    Steel material: Q235A

    Input excitation voltage: 150V Excitation current: 1.5A Frequency: 50Hz.

    Output DC voltage: 11.5kV DC current: 4A Frequency: 120000Hz.

    Welding speed: 50 m / min.

    Parameter adjustment: according to the welding line energy changes in time to adjust the output voltage and welding speed. Fixed parameters generally do not have to adjust.

Factors affecting strength of steel pipe

    Manufacturer of steel pipe like seamless steel pipe, ERW steel pipe, LSAW steel pipe, would make each kind of product as artwork. And we all know it is uneasy if the work don’t brilliant for engineering project. So even for steel pipe’s strength, we would like to have patience for researching it.

    First of all, the strength of the steel pipe relies on alloy composition. We should follow the high quality principle to add the alloy composition instead of violating it. All composition would include seamless and seamed steel pipe for substantially uniform strength alloy and its heat treatment. We can make it according to relative standard of the steel pipe.

    What’s more, tensile test and three-dimensional vibration test would be necessary before selling. We all know that tearing of steel pipe joint would happen almost in away from the welding spot or the heating place. Thus we have equipment test such as Chemical Component Analysis, Mechanical Properties (Ultimate tensile strength, Yield strength, Elongation), Technical Properties (Flattening Test, Bending Test, Blow Test, Impact Test), Exterior Size Inspection, Hydrostatic Test, X-ray Test and so on.

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