Production Technology Improving Process of ERW Steel Pipe

Straight seam welded pipe (ERW straight seam welded steel pipe) is formed on the hot rolled plate of the forming machine, the skin effect and proximity effect of the high frequency current, melting of the pipe edge heating to the extrusion roller pressure welding to achieve production. The application of high-frequency resistance welding method in pipeline production in the 1950s has witnessed more and more mature production technology and continuous improvement of product quality in the past decade or so.

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First of all, in the quality of raw materials, the production of ERW steel pipe has been significantly improved, the composition of the steel design of low carbon, low P, S, micro-alloying; smelting process smelting, ladle refining, vacuum degassing, continuous casting and other new technologies In addition to the ERW controlled rolling and cold rolling process, the technology has enabled the appearance size of the hot rolled steel strips of large and medium caliber ERW steel tubes to be greatly improved in appearance quality, physical properties and chemical properties. The steel pipelines produced by Baoshan Iron and Steel Company, the highest level of hot rolled strip steel in my country, have met the American Petroleum Institute API 5L standard and are at the international advanced level.

Followed by the middle and large diameter ERW molding welding and heat treatment process of the production process to achieve the computer automatic control, high frequency and computer automatic compensation system welding process heat input energy is effectively controlled to prevent welding heat input welding cold caused by low welding heat input and Excessive combustion caused by high energy. The heat treatment temperature control allows the heat treatment process to achieve the best results according to the process requirements, effectively ensuring the quality of the steel pipe welding and heat-affected zone.

In addition, the progress of ERW tube straight seam welded pipe inspection technology has achieved full online or offline ultrasonic or eddy current weld risk damage, and the hydraulic pressure test may be under the supervision of a computer, stress testing and regulatory requirements. The promotion and implementation of the standard and specification APIQ1 ISO9000 series ensure the quality assurance in the whole process of production, inspection, sales and service of medium and large caliber ERW straight seam steel pipes.

In recent years, various countries have been actively adopting ERW straight seam welded pipe and spiral welded pipe seamless pipe in place, in industrialized countries, ERW straight seam pipe diameter Ф610mm less, ERW steel pipe has reached about 70% of the proportion. Our production capacity of ERW Longitudinal also occasion enhanced.

Order--ERW Steel Pipe to UK

Product: ERW Steel Pipe

Standard: API 5L Gr.B

Specification: Ø219.1mm X 6.35mm X 6000mm.                                                       

                        Ø273.1mm X 6.35mm X 6000mm.

                        Ø355.6mm X 7.92mm X 6000mm

                        Ø457.2mm X 7.92 X 6000mm                                                                                           

                        Ø610mm X 9.53 X 6000mm"

Surface: Black Painting

Ends: BE

Quantity: 130.1t

Production Time: 30 DAYS

Destination: UK

Sales Expert: Landry 

Low-frequency Electric Resistance Welding

Low-frequency electric resistance welding (LF - ERW), is an obsolete method that was used to weld seams in oil and gas pipelines. It was phased out in the 1970s but as of 2015 some pipelines built with this method remained in service.

Electric resistance welded pipe (ERW steel pipe) is manufactured by cold-forming a sheet of steel into a cylindrical shape. Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material. Initially this manufacturing process used low frequency A.C. current to heat the edges. Over time, the welds of low frequency ERW pipe was found to be susceptible to selective seam corrosion, hook cracks, and inadequate bonding of the seams, so low frequency ERW is no longer used to manufacture pipe. This low frequency process was used from the 1920s until 1970. In 1970, the low frequency process was superseded by a high frequency ERW process which produced a higher quality weld. So the high frequency process is still being used to manufacture pipe for use in new pipeline construction. In the production of ERW steel pipe manufactured by Prime Steel Pipe, high-frequency ERW process is widely used, so that we can guarantee the quality of welding seam and produce high quality ERW steel pipe.

The Types of Electric Resistance Welding

We knew what is electric resistance welding (ERW) previously, next, Prime Steel Pipe will continue to share the types of Electric Resistance Welding. We will discuss high-frequency ERW (contact and induction) and rotary wheel contact welding (AC, DC, and square wave). And we will share the differences among the processes, as well as the power supplies and weld rolls.

All ERW processes have one thing in common–all of them produce a forged weld, although each process has different characteristics. Several electric resistance welding (ERW) processes are available for ERW steel pipe production. The two main types of ERW are high-frequency (HF) and rotary contact wheel.

High-frequency (HF) Welding

The two main aspects of HF welding are processes and power supplies. The two HF welding processes are HF contact and HF induction. In both processes, the equipment that provides the electrical current is independent from the equipment that supplies the forge pressure. Also, both HF methods can employ impeders, which are soft magnetic components located inside the tube that help to focus the weld current in the strip edges. In the case of HF induction welding, the weld current is transmitted to the material through a work coil in front of the weld point. The work coil does not contact the tube--the electrical current is induced into the material through magnetic fields that surround the tube. HF induction welding eliminates contact marks and reduces the setup required when changing tube size. It also requires less maintenance than contact welding. HF contact welding transfers weld current to the material through contacts that ride on the strip. The weld power is applied directly to the tube, which makes this process more electrically efficient than HF induction welding. Because it is more efficient, it is well-suited to heavy-wall and large-diameter tube production. HF welding machines also are classified by how they generate power. The two types are vacuum tube and solid-state. The vacuum tube type is the traditional power supply.

Rotary Contact Wheel Welding

In rotary contact wheel welding, the electrical current is transmitted through a contact wheel at the weld point. The contact wheel also applies some of the forge pressure necessary for the welding process. The three main types of rotary contact wheel welders are AC, DC, and square wave. In all three power supplies, electrical current is transferred by brush assemblies that engage slip rings attached to a rotating shaft that supports the contact wheels. These contact wheels transfer the current to the strip edges.

Difference between Seamless Stainless Steel Pipe and ERW Stainless Steel Pipe

There are some customer don’t know how to distinguish the seamless stainless steel pipe and ERW stainless steel pipe. Today, Prime Steel Pipe will discuss about differences between seamless stainless pipe and ERW stainless steel pipe.

What is the raw material required for manufacturing seamless & ERW stainless steel Pipes? Seamless Steel Pipe is made from a solid round steel ‘billet’ which is heated and pushed or pulled over a form until the steel is shaped into a hollow tube. Billets are procured both from indigenous suppliers and from abroad. HR Coils are required to manufacture ERW stainless steel pipes.

How to Identify Seamless or ERW Stainless Steel pipes?

To identify that a pipe supplied is seamless or ERW, Simply read the stencil on the side of the pipe. If it is ASTM A53, Type S means seamless. Type F is furnace but welded, type E is Electrical resist welded.

What is the difference between seamless stainless steel pipe and ERW stainless steel pipe?

1. ERW steel pipe is manufactured by rolling metal and then welding it longitudinally across its length. Seamless pipe is manufactured by extruding the metal to the desired length; therefore ERW steel pipe have a welded joint in its cross-section, while seamless pipe does not have any joint in its cross-section through-out its length.

2. In Seamless steel pipe, there are no welding or joints and is manufactured from solid round billets. The seamless pipe is finished to dimensional and wall thickness specifications in sizes from 1/8 inch to 26 inch OD. Applicable in for High-pressure applications such as Hydrocarbon Industries & Refineries, Oil & Gas Exploration & Drilling, Oil & Gas Transportation and Air and Hydraulic cylinders, Bearings, Boilers, Automobiles, etc.

3. ERW steel pipes are welded longitudinally, manufactured from Strip / Coil and can be manufactured upto 24” OD. ERW steel pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge. It is mainly used for low/ medium pressure applications such as transportation of water / oil.

4. Common sizes for ERW Steel Pipe range from 2 3/8 inch OD to 24 inch OD in a variety of lengths to over 100 feet. Surface finishes are available in bare and coated formats and processing can be handled on site to customer specifications.

Difference between Seamless Stainless Steel Pipe and ERW Stainless Steel Pipe

There are some customer don’t know how to distinguish the seamless stainless steel pipe and ERW stainless steel pipe. Today, Prime Steel Pipe will discuss about differences between seamless stainless pipe and ERW stainless steel pipe.

What is the raw material required for manufacturing seamless & ERW stainless steel Pipes? Seamless Steel Pipe is made from a solid round steel ‘billet’ which is heated and pushed or pulled over a form until the steel is shaped into a hollow tube. Billets are procured both from indigenous suppliers and from abroad. HR Coils are required to manufacture ERW stainless steel pipes.

How to Identify Seamless or ERW Stainless Steel pipes?

To identify that a pipe supplied is seamless or ERW, Simply read the stencil on the side of the pipe. If it is ASTM A53, Type S means seamless. Type F is furnace but welded, type E is Electrical resist welded.

What is the difference between seamless stainless steel pipe and ERW stainless steel pipe?

1. ERW steel pipe is manufactured by rolling metal and then welding it longitudinally across its length. Seamless pipe is manufactured by extruding the metal to the desired length; therefore ERW steel pipe have a welded joint in its cross-section, while seamless pipe does not have any joint in its cross-section through-out its length.

2. In Seamless steel pipe, there are no welding or joints and is manufactured from solid round billets. The seamless pipe is finished to dimensional and wall thickness specifications in sizes from 1/8 inch to 26 inch OD. Applicable in for High-pressure applications such as Hydrocarbon Industries & Refineries, Oil & Gas Exploration & Drilling, Oil & Gas Transportation and Air and Hydraulic cylinders, Bearings, Boilers, Automobiles, etc.

3. ERW steel pipes are welded longitudinally, manufactured from Strip / Coil and can be manufactured upto 24” OD. ERW steel pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge. It is mainly used for low/ medium pressure applications such as transportation of water / oil.

4. Common sizes for ERW Steel Pipe range from 2 3/8 inch OD to 24 inch OD in a variety of lengths to over 100 feet. Surface finishes are available in bare and coated formats and processing can be handled on site to customer specifications.

The Introduction of ERW Galvanized Steel Pipe

Pipe manufacturer Prime Steel Pipe will introduce ERW galvanized steel pipe for everyone next. What is ERW steel pipe? For pipes size 4 inch (10.2mm) OD and below, strip is fed into a set of forming rolls which consists of horizontal and vertical rollers so placed as to gradually from the flat strip in to a tube which is then allowed to pass the welding electrodes. The electrodes are copper disks connected to the secondary of a revolving transformer assembly. The copper disk electrodes make contact on each side of the seam and temperature is raised to the welding point. Outside flash is removed by a cutting tool as the tube leaves the electrodes, inside flash is removed either by an air hammer or by passing a mandnel through the welded tube after the tube has been cooled. This is termed as Electric Resistance Welded Pipe.

ERW galvanized steel pipes has long been one of the most used building materials in the world. ERW galvanized steel pipes can resist the attack of wild, water & road salts. ERW steel pipes are used in Water Pipelines, Agriculture and Irrigation (Water Mains, Sewerage Systems, Industrial Water Lines, Plant Piping, Deep Tube-Wells & Casing Pipes). Other popular application area includes usage in gas pipe lines (pipe lines for natural gas, LPG and other non-toxic gases).

ERW galvanized steel pipe is steel pipe covered with a protective coating of zinc that greatly reduces its tendency to corrode and extends its life expectancy. It may be used in residential water supply lines, but not gas lines because natural gas causes the zinc to flake off and clog the system. It's not frequently used for water supply lines because the minerals in the water react with the galvanizing material and form scale, which builds up over time and will eventually clog the pipe. ERW galvanized steel pipe during galvanizing, steel is immersed in a molten zinc bath, ensuring a tough, uniform barrier coating. Zinc’s natural corrosion resistance provides long-term protection, even in outdoor environments. Apart from preventing water corrosion, it is also equally effective in dry & indoor environments.

The fitting for ERW galvanized steel pipe is galvanized malleable (soft) cast iron. They connect by screwing onto the threaded pipe, after applying a small amount of pipe joint compound on the threads. Larger diameter pipe is welded rather than threaded.

International Market Continues to Force, South African Customers Visit Shinestar Head office

Shinestar in the international market continue to develop in recent years, the company's various products are extremely popular with more and more foreign customers. Recently, the representative of customer from South Africa arrived at the headquarters of Shinestar and conducted a field visit, Shinestar company had a warm reception to guests from afar.

This time South African customers visited Shinestar, on the one hand they conducted a field visit to Shinestar, on the other hand they wanted to achieve in-depth cooperation of ERW steel pipe with us. Accompanied by the Shinestar Group shareholders, group vice president, general manager and client manager of Prime Steel Pipe, South African customers visited the headquarters of Shinestar, Shinestar conducted a comprehensive understanding. General manager of Prime Steel Pipe introduced the current development of Shinestar, product technology improvements and past cases to South African customers in detail. For the various problems raised by customers, business elites accompanied have made a detailed solution, their excellent professional knowledge and work ability left a deep impression to the customer.

After the visit, South African customers had a highly recognition on the strong company strength, professional production platform, strict quality control of Shinestar, and had in-depth discussion on the future cooperation between the two sides. In this cooperation, customers from South African hoped that they could purchase 3,000 tons of ERM steel pipe every two months from Shinestar, while they would continue to cooperate the follow-up of the demand for section, and they said that they would finalize the details of the contract at the first time after returning to their motherland.

Shinestar as the overall procurement of steel services that based on the China and provided the global service, its steel products by independent research exported to Europe, the Middle East, Southeast Asia, North America, Australia, more than 100 countries and regions, has gradually become the international market more and more hot star. This time South African customers visited here, not only strengthened the close communication of Shinestar to foreign customers, but also show the strength of Shinestar to international.

With the promotion of Shinestar Group's globalization strategy and the expansion of overseas business, which also put forward new requirements to the company's development. In the future, Shinestar will effectively grasp the production, quality, sales, service and other links, accurately grasp the opportunities, and strive to open up the market, to further meet the changing needs of customers around the world, more robust towards the international arena.

Updated Price List for Hot Rolled ERW Pipe on June 14, 2017

Hot Rolled ERW Steel Pipe Price 2017/06/14

Updated Price List for Small Diameter ERW Pipe on June 14, 2017

The Effect of Input Power on ERW Steel Pipe Production

When using high frequency technology to produce ERW steel pipe, controlling the input power of High-frequency welding is very important. So what effect does it have on ERW steel pipe production? And what should steel pipe factory do for that? Next, ERW steel pipe manufacturer Prime Steel Pipe who has years of experience on manufacturing carbon steel pipe will give your answer.

If the input power is too small, the pipe groove is not heated enough to reach the welding temperature, which can cause the welding failure such as pseudo soldering, unsoldering and slag welding. If the power is too large, it will affect the welding stability. When the heating temperature of the pipe groove surface is much higher than the temperature required for welding, which will result in severe splashing, pinholes, slag and other defects, those defect are known as over burning defects. When manufacturing ERW steel pipe, the input power of high-frequency welding need to adjust and determine according to the thickness of the wall and the molding speed. Different molding methods, different unit equipment, and different material grade of steel all need us to sum up from the production line, and work out high-frequency process that suitable for their own equipment.

Brief Introduction of Scaffolding Pipe

Scaffolding pipe is usually made up of LSAW steel pipe or ERW steel pipe, its process types include: hot rolled/hot expended, electric resistance/high frequency. It has a variety of specifications, according to the diameter it can be divided into: Φ3.0, Φ2.75, Φ3.25, Φ2.5. Its length also has a variety of specifications: half a meter in a specification from 1 to 6 meters; it can be processed in accordance with customer specifications. The thickness is generally 2.4--2.7 mm and the diameter is 48 mm. The surface is generally not handled, individually coated with anti-rust paint. The material scaffolding pipe is: Q195, Q215 or Q235. The implementation of standard of scaffolding pipe is: SY/T5768-95 and GB/T3091-2001.

Different types of construction use different scaffolding and formwork support. At present, the bridge support frame mostly uses bowl buckle scaffolding, but also uses door scaffolding. The main structure of the construction of scaffolding mostly uses scaffolding scaffolding, scaffolding pole vertical distance is generally 1.2 ~ 1.8m; span is generally 0.9 ~ 1.5m.

Adaptability of scaffolding pipe:

1) to build various forms of scaffolding, templates and other support frame;
2) assembly of bone frame;
3) to set up ramps, sheds, stands and other temporary structures;
4) for other kinds of scaffolding support, strengthen the bar.

ERW Steel Pipe Production: The Role of Weld Preheating

In the production of ERW steel pipe, high frequency technology used by pipe manufacturer, other welding of important components, welding of alloy steel and welding of thick parts all require preheating before welding. The main roles of preheating before welding are as follows:

(1) Weld peheating can slow down the cooling rate after welding, which is conducive to the spread of diffusible hydrogen in the weld metal, and avoids producing hydrogen to result in cracking. At the same time, it also reduces the degree of hardening of the weld and heat affected zone and improves the crack resistance of the welded joints.

(2) Weld preheating can reduce the welding stress. Uniformly preheating or entirety preheating can reduce the temperature difference (also known as temperature gradient) between welds in the weld area. In this way, on the one hand it reduces the welding stress, on the other hand, it reduces the welding strain rate, which is help to avoid welding cracks.

(3) Weld preheating can reduce the restraint degree of the welded structure, especially to reduce the degree of restraint of the corner joint. With the increase of the preheating temperature, the crack rate decreases.

The choice of preheating temperature and interlayer temperature is not only related to the chemical composition of steel and electrode, but also to the rigidity of welded structure, welding method, ambient temperature and so on. It should be determined after considering these factors. In addition, the preheating temperature in the direction of the steel plate thickness uniformity and uniformity in the weld area, has an important impact on reducing the welding stress. The width of the local preheating should be determined according to the degree of restraint of the workpiece to be welded, generally it should be around the weld area three times the wall thickness, and is not less than 150-200mm. If the preheating is not uniform, not only does not reduce the welding stress, but also will appear to increase the welding stress situation.

So when Prime Steel Pipe manufactures ERW steel pipe or other welded pipe, we will take control of preheating temperature strictly, so that we can produce perfectly good carbon steel pipe.

The Use of ERW Steel Pipe

High frequency electric resistance welded pipe, also known as ERW steel pipe. ERW has many advantages, such as high production efficiency, low-cost, saving in material, and easy-to-automation. It is a kind of important welding technology which is widely used in various industrial sectors such as aviation, energy, electricity, automobile, light industry and so on.

ERW steel pipe uses hot rolled coil as raw material, its wall thickness is uniform and is controlled at ± 0.2mm or so, the two ends of the pipe should repair the end, bevel, and cut to length according to the United States APl standard or GB/T.1 standard. Compared with the submerged arc welding process, ERW welding process does not add any welding materials, weld molding has not been hot-melting state, the weld metal goes through the recrystallization process, so the formed weld is completely the same chemistry as the base metal. The steel pipe after welding will be annealing, manufacturing cold forming internal stress, welding internal stress are improved, so ERW steel pipe comprehensive mechanical properties better.

ERW steel pipe is mainly used for conveying oil, gas and other vapor-liquid objects, to meet the high and low pressure requirements. At present, the field of transportation and transportation in the world plays a heavy role. In recent years, the engineering gas has been widely used ERW steel pipe as the main gas pipe network.

About more details about definition, manufacturing process and application of ERW steel pipe, you can click the hyper-link to know. If you have any requirements of carbon steel pipe or steel pipe fittings, Prime Steel Pipe will give you the most complete solution.

The Effect of Input Power on ERW Steel Pipe Production

When using high frequency technology to produce ERW steel pipe, controlling the input power of High-frequency welding is very important. So what effect does it have on ERW steel pipe production? And what should steel pipe factory do for that? Next, ERW steel pipe manufacturer Prime Steel Pipe who has years of experience on manufacturing carbon steel pipe will give your answer.

If the input power is too small, the pipe groove is not heated enough to reach the welding temperature, which can cause the welding failure such as pseudo soldering, unsoldering and slag welding. If the power is too large, it will affect the welding stability. When the heating temperature of the pipe groove surface is much higher than the temperature required for welding, which will result in severe splashing, pinholes, slag and other defects, those defect are known as over burning defects. When manufacturing ERW steel pipe, the input power of high-frequency welding need to adjust and determine according to the thickness of the wall and the molding speed. Different molding methods, different unit equipment, and different material grade of steel all need us to sum up from the production line, and work out high-frequency process that suitable for their own equipment.

Pipe Application: Pipeline Transport

Pipeline transport is a mode of transportation that using steel pipe as a transport machine to transport liquid and gas materials in long distance, is a mode of transportation that transporting oil, coal and chemical products from the place of production to market, is a special component of trunk transportation in unified transport network. The cost of using pipeline to transport oil is high than that of water transport, but it is cheaper than railway transportation. Pipeline transport features to higher transportation capacity, continuous, rapid, economical, safe, reliable, smooth and less investment, less land occupied, low cost, and it can realize the automatic control. In addition to widely used in oil and natural gas long-distance transport, but also can be used in transporting ore, coal, building materials, chemicals and food.

The main pipe used in pipeline transportation is the steel pipe, in accordance with its manufacturing process can be divided into seamless steel pipe and welded steel pipe, and welded pipe can be divided into ERW steel pipe, LSAW steel pipe, spiral welded pipe, etc. According to different enviroment and diffferent application, we will select the steel pipe produced by different technology. Prime Steel Pipe are positioned as a steel pipe manufacturer and exporter for carbon steel pipe, stainless steel pipe, seamless steel pipe, welded steel pipe, steel pipe fittings, can provide all kinds of carbon steel pipe with different specifications and standards according to the requirements of customers.

The main advantages of pipeline transportation can be summarized as follows:

(1) Large capacity
An oil pipeline can continue to complete the delivery task. According to the difference of the size of the pipe diameter, its annual transport capacity can reach to several million tons or tens of millions of tons, or even more than 100 million tons.

(2) Less land occupation
Transport pipeline was usually buried in the ground, its land occupation is very small; the construction practice of transport system proved that the part of transport pipeline buried in the underground took up more than 95% of total length of the pipeline. So the permanent land occupation is very small, respectively amounts to 3% of the road and about 10% of the railway.

(3) Short construction period and low cost
A lot of practice has proved that, compared to the same traffic volume of the railway construction period, in general,the construction cycle of pipeline transportation system is shorter than 1/3.

(4) Safe and reliable, strong continuity
As the oil and gas is flammable, explosive, volatile and easy to leak, using pipeline transport is safe, and can greatly reduce the volatile loss, and the pollution caused by the leakage of air, water and soil can be greatly reduced.

(5) Little energy consumption, low cost and good efficiency
Pipeline transportation is a continuous project, the transport system does not exist no-load travel, thus the transport efficiency of system is high. Theoretical analysis and practical experience has proved the larger the diameter of the pipeline is, the farther the shipment distance is, the larger the traffic capacity is, the lower the transportation cost is. Using oil transport as an example, the transport costs ratio of pipeline transportation, water transport, rail transport is 1: 1: 1.7.

Types of Welded Steel Pipe

1. Welded steel pipe (GB/T3092-1993) used in Low-pressure fluid delivery, also known as the general welded pipe, commonly known as black tube. It is the welded steel pipe that used to transport of water, gas, air, oil and heating steam, and other generally fluids with lower pressure. Steel pipe is divided into ordinary steel pipe and thickened pipe according wall thickness; is divided into non-threaded steel pipe (light pipe) and threaded steel pipe according to the form of pipe end. The specifications of the steel pipe are denoted by nominal caliber (mm), and the nominal caliber is the approximate value of the inner diameter. It traditionally uses inches to express, such as 11/2 and so on. Welded steel pipe used in Low-pressure fluid delivery in addition to directly use for the transport of fluid, but also is used as the original tube of galvanized welded steel pipe used in Low-pressure fluid delivery.

2. Galvanized welded steel pipe (GB/T3091-1993) used in Low-pressure fluid transmission, also known as galvanized welded steel pipe, commonly known as white tube. It is the hot dipping galvanized welded (butt weld or electrowelding) steel pipe used to transport water, gas, air oil and heating steam, warm water and other generally fluids in lower pressure. Steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe according to wall thickness; is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe according to the form of pipe end. It traditionally uses inches to express, such as 11/2 and so on.

3. Ordinary carbon steel electric wire conduit (GB3640-88) is used in electrical installation ( such as the industrial and civil construction and installation of electrical equipment and other works) to protect the wire of the steel pipe.

4. LSAW steel pipe (YB242-63) is the pipe that the weld longitudinally parallel to steel pipe. It is usually divided into metric welded steel pipe, welded thin-walled pipe, transformer cooling tubing and so on.

5. SSAW steel pipe (SY5036-83) for pressurized fluid delivery is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature and welded by double-sided submerged arc welding, used for pressurized fluid delivery. The loading capacity of steel pipe is strong, welding performance is good, after a variety of strict scientific inspection and testing, it can be used safely and reliably. The diameter of steel pipe is big, transport efficiency is high, and it can save the laying of pipeline investment. So it is mainly used for conveying oil and gas pipelines.

6. ERW steel pipe used for pressurized fluid transmission (SY5038-83) is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, welded by high-frequency lap welding, used for pressurized fluid transportation. The loading capacity of steel pipe is strong, plasticity is good, and it is easy to weld and machine shaping. After a variety of rigorous and scientific inspection and testing, the pipe is safe and reliable to use, the diameter of steel pipe is large, transport efficiency is high, and it can save the laying of pipeline investment.

7. Spiral welded steel pipe (SY5037-83) used in general low-pressure fluid transmission is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use double-sided automatic submerged arc welding or single-sided welding method to weld. It is used for water, gas, air and steam and other general low-pressure fluid transmission.

8. ERW steel pipe (SY5039-83) used in general low-pressure fluid transmission is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use high-frequency lap welding to weld,. It is used for general low-pressure fluid delivery.

9. Spiral welded steel pipe (SY5040-83) used as pile is made of hot-rolled steel coil as tube blanks, spirally forming in normal temperature, use double-sided submerged arc welding or high-frequency welding to make. It is used for civil construction, wharf, bridge and other foundation pile steel pipe.

Production Process of High Frequency Welded Pipe

The production process of high-frequency welded pipe mainly depends on the variety of products. From raw materials to finished products needs to go through a series of processes, and the completion of these processes requires a variety of mechanical equipment and welding, electrical control, detection devices. These equipment and installation in accordance with the different process requirements a variety of reasonable layout.

Taking ERW steel pipe as an example, typical production process of high frequency welded pipe is shown below:

Uncoiling - Leveling - End cutting - End shearing and butt welding - Spiral loop/accumulator - Edge cutting/Edge milling - Ultrasonic detection - Forming - High frequency welding + Burr removing - Welding seam ultrasonic detection (offline online) + Metallographic examination - Medium frequency heat treatment - Air cooling - Water cooling - Sizing - Fly cutting - Flush out - Cutting/Cropping - Flattening testing - Straightening - End facing and bevelling - Hydrostatic testing- Ultrasonic detection for welded seam and pipe end - Marking and coating - Finished product

High-frequency Welding Principle of Longitudinal Welded Pipe

The emergence and maturity of high-frequency welding technology, directly promoted the development of Longitudinal Welded Pipe industry, it is the key processes of Longitudinal Welded Pipe(ERW steel pipe) production. High-frequency welding originated in the fifties of last century, it is a new welding process that uses the skin effect and adjacent effects produced by high-frequency current to make the steel plate and other metal materials docked.Good or bad quality of high-frequency welding directly has an impact on the overall strength, quality grades and production speed of welded pipe products. As a manufacturer of welded pipe, you must understand the basic principles of high-frequency welding, understand the structure and working principle of high-frequency welding equipment, and understand the high-frequency welding quality control points.

Relatively the 50Hz AC current frequency speaking, high frequency is generally refers to 50KHz ~ 400KHz high frequency current. When high-frequency current flow through the metal conductor, it will produce two strange effects: skin effect and proximity effect. And high-frequency welding just uses these two effects to weld the steel pipe. So, what are the those two effects?

Skin effect

Skin effect refers to a certain frequency of AC current flow through the same conductor, the current density is not evenly distributed in all sections of the conductor. It will mainly focus on the surface of the conductor, that is, the density of the current in the conductor surface is big, the density of the conductor inside is small. So we vividly called it "skin effect". Skin effect is usually measured by the penetration depth of the current, the smaller the penetration depth, the more obvious the skin effect. And the penetration depth is proportional to the square root of the resistivity of the conductor, and is inversely proportional to the square root of the frequency and permeability. In layman's terms, the higher the frequency, the more concentrated current will be on the surface of the steel plate; the lower the frequency, the more dispersed current will be on the surface. It must be noted that, although the steel is a conductor, its permeability will drop with the temperature rise, that is, when the steel plate temperature increases, the permeability will decline, skin effect will be reduced.

Proximity effect

The proximity effect refers to the fact that when the high frequency current flows counter currently in two adjacent conductors, the current will flow collectively toward the edges of the two conductors. Even if there is a shorter side in two conductors, the current does not flow along the shorter route. We call this effect "proximity effect". Proximity effect is essentially affected by inductive reactance, inductance plays a leading role in the high frequency current. The proximity effect increases as the frequency increases and the spacing of adjacent conductors approaches. If adding a core around the conductor, the high frequency current will be more concentrated on the surface of the workpiece.

These two effects are the basis for achieving high frequency welding of metals. High-frequency welding just used the skin effect so that the energy of high-frequency current concentrated in the workpiece surface, and used the proximity effect to control the location of high-frequency current flow and range. The speed of the current is very fast. It will heating and melting adjacent to the edge of the steel plate in a very short period of time, and achieve docking through the extrusion.

The Definition, Manufacturing Process and Application of ERW Steel Pipe

Some buyers haven't a very clear concept about what is ERW pipe and what is ERW tube manufacturing process, they also don’t know its application. Today, Prime steel pipe will give you a detailed introduction about that.

What is ERW pipe?

ERW pipe (also called ERW steel pipe) is the abbreviation Electric Resistance Welded Pipes. Electric resistance welding refers to a group of welding process (including spot and seam welding) that produce coalescence of faying surfaces where heat to form the weld is generated by the electrical resistance of material combined with the time and the force used to hold the materials together during welding. ERW steel pipes and tube are available in various qualities, wall thicknesses, and diameters of the finished pipes.

What is ERW tube manufacturing process?

ERW steel pipe is manufactured by rolling metal and then welding it longitudinally across its length. ERW steel pipes are welded longitudinally, manufactured from Strip / Coil and can be manufactured up to 24”OD. ERW pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge.

Typical ERW tube manufacturing process of Prime Steel Pipe generally involves the following stages in a step by step procedure.

The application of ERW steel pipe

ERW steel pipes are used in various engineering purposes, fencing, scaffolding, line pipes etc. It is available in lengths from single random to 120 feet depending on mill capability. What's more, ERW steel pipes are usually used for Agricultural purposes, Drinking Water for housings, in collieries for extraction of Water, Thermal Powers, Transports, Hand pumps for deep boring wells, as a strong protection for cables by Telecom Department, Structural Purposes etc. ERW steel pipe is available with square ends or beveled for welding, threaded and coupled and victaulic grooved. Surface finish of it is available in black or bare, or with protective coatings.

Prime Steel Pipe have a very large production capacity of ERW steel pipes, so that we can manufacture ERW pipes and tubes of different size and shape based on the customers requirements.