ASTM A252 Welded Steel Pipe

ASTM A252 standard specification for welded steel pipe piles.

This specification covers nominal wall cylindrical structural steel pipe piles in which the steel cylinder acts as a permanent load-carrying member or as a shell to form cast-in-place concrete piles. Each welded pile shall be made by seamless, electric resistance welding, flash welding or fusion welding with longitudinal, helical-butt, or helical-lap seams.  

Applications: the steel cylinder acts as a permanent load carrying member or as a shell to form cast–in–place concrete welded steel pipe piles.

Sizes: 6” – 20”

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AWWA C200 Coating Steel Water Pipe

Water pipeline AWWA C200 coating steel pipe is widely used in the following fields/industries:
Hydraulic power station, potable
Water supply industry, irrigation penstock, Sewage disposal pipe line

AWWA C200 standards covers butt-welded, straight-seam or spiral-seam steel pipe, 6 in. (150 mm) and larger, for transmission and distribution of water, including fabrication of pipe, requirements of welding operations, permissible variations of weight and dimensions, preparation of ends, fabrication of specials, inspection, and test procedures.

Inspection
All work performed and material furnished under this standard may be inspected by the purchaser, but such inspection shall not relieve the manufacturer of responsibility to furnish material and perform work in accordance with this standard.

Quality assurance
The manufacturer shall maintain a quality-assurance program to ensure that minimum standards are met. It shall include a certified welding inspector (AWS QC1) to verify that welders and welding procedures are qualified, procedures are being followed with limitation of testing, and quality-assurance functions are being implemented.

Defects
The finished pipe shall be free from unacceptable defects. Defects in seamless pipe or in the parent metal of welded steel pipe will be considered unacceptable when the depth of the defect is greater than 12.5% of the nominal wall thickness.
The repair of defects will not be permitted if the depth of the defect exceeds 1/3 of the nominal wall thickness of the pipe and if the length of that portion of the defect in which the depth exceeds 12.5% is greater than 25% of the outside diameter of the pipe. Each length of repaired pipe shall be tested hydrostatically in accordance with standard requirements.

Marketing
A serial number or other identification shall be painted in a conspicuous location on each section of structural steel pipe and each special section.

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Advantage of DSAW Steel Pipe

In accordance with the cross-section and shape,DSAW welded steel pipe is divided into the sub-shaped tubes and tube. Perimeter commensurate area of ​​a circle is the largest, so you can transport more liquid. Therefore, the vast majority of DSAW steel pipe, each spiral are tightly controlled after the hydrostatic test, the test pressure and the time by the steel pipe pressure microcomputer monitoring device, the test parameters automatically printed record. The specific requirements of spiral strip is to forward the weldability of structural steel pipe,reducing the sulfur content in the steel are beneficial to improve the toughness of the steel pipe and crack arrest. This can also reduce the sulfide inclusions, transfers, advance steel crack resistance. Phosphorus content in hot-rolled strip is as low as possible, because the phosphorus on the strip, toughness and weldability harm, thus reducing the phosphorus content can be directly forward weldability may be appropriate to add additional titanium, vanadium, niobium content. LSAW steel pipe containing Ni in an acidic environment, the corrosion resistance is strong, containing sulfuric acid or hydrochloric acid environment, the higher the spiral of Ni content, the stronger the corrosion resistance. In general circumstances, only in the spiral Cr can prevent the erosion phenomenon. More information,pls visit:Hunan great steel pipe co.,ltd

Pressure Piping

Pressure piping(stress pipe) means carbon steel pipe of all under internal pressure or external pressure, regardless of the media how the tube.Pressure pipeline is part of the pipeline, and used for transmission, distribution, mixing, separation, discharge, measurement, control and suppression of fluid flow from the pipe, fittings, flanges, bolts, connections, gaskets, valves, and othercomposed of parts or compression parts and supporting parts consisting of assembly assembly.

Pressure mild steel pipe operations are generally in the outdoor way of laying overhead along the ground, buried, and often high-altitude operations, poor environmental conditions, quality control is higher. As the quality control aspects of the interlocking, organic combination of a part of the slightest carelessness are quality problems caused. Welding is a key work in the construction of pressure pipelines, its quality, efficiency directly affects the safe operation of engineering and manufacturing duration, so the process of quality control is more important. According to the requirements of the construction of welded steel pipe must strengthen the management of personnel, equipment, materials, process documents, and the environment. Take strict measures in order to ensure the quality of the welding of pressure piping to ensure the realization of high-quality welding engineering.

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JCOE Steel Pipe Production Process

JCOE manufacturing technology is developed in the 1990s as a LSAW steel pipe forming process, the process of molding process is the first major steel mill edge (or planing) after pre-bending by longitudinal side, and then type → J-→ C O-order molding, stamping each step are the basic principles of three-point bending. Because it is a progressive multi-pass pressing, it must address the following questions: how to determine the die shape, the upper die and lower die stroke distance, and how much press pass in order to ensure the most appropriate bend radius and the best opening round hair tube. But these issues with the steel plate, steel plants of different mechanical properties of concrete, pipe size (diameter and wall thickness), which in turn is very complex. Currently mainly by "trial and error", that is, whenever replacement or new steel specifications, we take a certain number of sample pressure test, worked out the right amount of punch. Trial and error method is more reliable, but the efficiency is relatively low.

As more DSAW steel pipe process parameters, only through trial and error method is quite cumbersome. In order to obtain a mature technology, and even a few months of trial and error process. And trial and error process is often a fixed shape and spacing of the die, only to explore the punch stroke, so the results obtained may not be optimal, there is no full unit capacity. System so it is necessary to study the factors affecting the shape, or even to establish a theoretical formula, developed with the experience of trial and error molding process, eliminating the need or less need to test, trial costs and reduce time and increase productivity.

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Steel Pipe Surface Defects

From the use of point of view, the mild steel pipe surface defects can be divided into three categories: 

① high temperature oxides, scarring, double skin, pits, and other types of defects. Such defects are generally not related to the "internal injuries" of the materials, manufacturing 
standards allow a certain size (depth) of defects, should be cleared for defects exceeding. 

② mechanical bumps. Such defects are neither involved in "internal injuries" not involved in processing the merits of the defect outline is clear, it is considered to be the most sensitive class of defects. Therefore allow the existence of indicators more relaxed than the first. 

③ cracks class defects (cracks). The existence of such defects often precedes the rationality of the process, especially when the carbon steel pipe surface cracks indicates that the steel pipe inside the metal in an unstable state. Therefore, when such defects, the removal of excessive defects at the same time, but also to analyze the causes in order to determine the merits of the intrinsic quality of the material, if necessary, add other test measures. In addition, such defects were sharp shape, sensitive to the most serious shortage of El, so often given the more stringent restrictions on the project.


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Steel Pipe Surface Treatment

The surface quality of steel pipes mainly in the thick surface oxide, surface cracking, surface re-skin, surface mechanical bumps. Hot-rolled steel pipe in the finished or cold-rolled steel during the heat treatment after the formation of a layer of thick and strong adhesive force, high-temperature oxide. The presence of oxides is not only poor steel appearance quality will also affect the use of steel pipe, which is not allowed by the standard. Such oxides with the general sandblasting is difficult to remove, use pickling or mechanical polishing method to clear the construction site generally do not have the processing conditions. Operations, some Steel Plant has with such oxides steel pipe factory, a great deal of trouble to the scene Shi Ding. Therefore, before the steel pipe factory must Yan Geqing to get rid of such oxides. Surface cracking occurred in the hot-rolled steel, common in carbon steel pipe and mild steel pipe, caused mainly due to the processing of residual stress caused by the huge surface tension, and after rapid cooling. Surface cracking does not belong to crack (not involving internal injuries), but it has some of the characteristics of the crack, in many conditions (such as heat, cold, stress corrosion cracking environment, etc.) will be formed to some extent, notch sensitivity effects, which reduce the life of the steel pipe, and even steel pipe failure. Therefore, before the steel pipe factory, be sure to cracking cleared out. Surface re-skin is common in cold-rolled or cold drawn steel pipe, did not deal with due to the billet surface or abrasive. Re-skin the existence will seriously affect the appearance quality of the structural steel pipe, steel pipe was not cracking is severe, but in some situations will still have some impact. The improved approach is to strengthen production management, improve and control the billet surface quality and the abrasive quality. Mechanical bumps is one of the most common quality problems, mainly arising from the production, handling and transportation process. Steel pipe bumps Department will form a structural discontinuity in use is a source of stress concentration, but also notch sensitive. Compared with the crack, the clear outline of the mechanical bumps defects and does not involve the "internal injuries" of the metal, the standards allow a certain depth of the bumps, but in some of the more sensitive conditions, or bruise depth exceeds a certain value should be grinding to eliminate, making it a smooth transition. More information,pls visit:Hunan great steel pipe co.ltd

How to deal with the challenge of the global economy？

2017 will be a year of challenges and opportunities coexist, the world economy will face a huge challenge. As a manufacturer and services vendors of carbon steel pipe, welded steel pipe, line pipe, ERW pipe, LSAW steel pipe, Shinestar Group has always been focused on the development of the global economy. Today, Shinestar  steel research institute would like to talk the method of China how to deal with the challenge of the global economy.　

Firstly, look for the balance of the fiscal and monetary policy combination, carefully deal with it. From the Angle of demand, if you take more loose fiscal policy, it is good for economic growth but not conducive to reduce debt. Loose monetary policy can support aggregate demand, encourage private spending, but also may bring negative effects, such as low long-term interest rates are likely to cover up the structural problems of the economy and financial system, and squeeze profits leads to the more risky loans.

Secondly, continue to promote the structural reform is important. Low-income countries can focus on improving infrastructure, legal system, promote the development of capital market, etc. Developed economies can focus on improving labor supply and create better innovation incentive mechanism, and improve productivity growth. In general, improve infrastructure, strengthen the banking system robustness and medium can help you in all countries.

Thirdly, should continue to open international trade development. International trade to optimize the allocation of resources, improve the specialization of production, reduce the production cost, eventually bring economies of scale and increase to comprehensive economic prosperity; Also can promote the spread of knowledge and technology, new product research and development and productivity growth. International trade back can only deepen and delay the downturn of economic growth, not conducive to economic prosperity.

Fourth, promote inclusive growth. Many countries need to continue to strengthen the social safety net, improve health care, education and other infrastructure and conditions, to achieve more professional and regional flow of personnel, taking tax incentives to encourage women into the labor market, etc.

Fifth, face and deal with the economic transformation of the digital revolution correctly. While strengthen the social security system, improve the level of education, further strengthen vocational training and technology promotion, promote production quickly and effectively to reallocate resources to the most productive industries and departments, etc., to support people to adapt to the new job requires as soon as possible, and develop new technology into productivity.

Sixth, the international community needs to coordinate global policy combination, to revive the economy, benefit sharing. International coordination can make the individual countries support demand measures to produce more positive, the positive spillover effect, so as to strengthen its global effect, create more policy space.

In a word, the multiple challenges need strong, coordination of policy measures. Demand management should be in parallel with a reform of the supply side, fiscal, monetary policy, structural reform needs to cooperate, adjust measures to local conditions. the policy measures of each country should be coordinated, have the effect of auxiliary to each other.

Opportunities and challenges which China's economic development facing is on the rise, Shinestar Group will also be a scientific analysis of the new features of the international situation, efforts to seize opportunities, meet challenges and strive to produce more high quality structural steel pipe, welded steel pipe, line pipe, ERW steel pipe, DSAW steel pipe and other products, as with the international competitiveness of steel enterprises.

Storage of Steel Pipe

Pipe may not be directly stacked on the floor, steel or concrete surface, the first layer of steel pipe from the ground at a distance not less than 0.20m. To avoid carbon steel pipe damp, dust and pollution, steel pipe (or tube bundle) shall be placed in a dusty, damp places, tying both ends of the pipe must be protected with plastic or paper bags, etc., to prevent dust from entering.

Rack or stack level should be neatly arranged, and there is a clear marker number. Pipe should heat number (Lot), variety of different sizes and materials are placed in the designated rack or stack position. The same rack or stack position is not allowed to store the same size as (or similar), the same type of material and outline different heats of steel.

To prevent bending or mild steel pipe table injury, steel pipe (or tube bundles) should be placed at appropriate intervals and in the same horizontal plane on the sleepers, end of the tube to ensure alignment. For annealed brass, aluminum and similar hose should be placed between layers of isolation sleepers, each for at least two sleepers should be placed in a vertical pipe, and up and down on the positive, to ensure straight alignment. If the pipe

In case of the absence of feeder layer code (including code square stamp) stacked, should be properly placed wedge or use other methods to prevent rolling of steel pipe.

After cold-rolled, cold-drawn or bright annealed structural steel pipe does not allow open storage. If that stock conditions, open storage should be required to take appropriate precautions to avoid rain, snow, fog and other corrosive media and a lot of dust pollution pipe.

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Rust Protection of Welded Steel Pipe

As the individual quality of  welded steel pipe is relatively large, it must be stacked in the outdoors, but it will be difficult to avoid the sun and rain, so the problem has been plagued with rust spiral pipe storage time and conditions. Therefore, we need to conduct a comprehensive understanding of the spiral steel pipe rust prevention.

The main use of steel wire brush and other tools on the steel surface grinding, spiral steel pipe cleaning and preheating can be removed loose or tilt of the oxide, rust, welding slag and so on. Hand tools to achieve rust Sa2 level, power tools rust can be achieved Sa3 level, if the steel surface attached to a solid oxide scale, tool rust effect is not ideal, less than anti-corrosion construction requirements of the depth of the anchor pattern. Pickling

The use of solvents, emulsion cleaning low pressure fluid delivery welded steel pipe surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove steel surface rust, oxide, welding, Anti-corrosion production only as an auxiliary means.

General use of chemical and electrolytic two ways to do pickling treatment, pipeline corrosion only chemical pickling, can remove the oxide, rust, old coating, and sometimes can be used as a reprocessing after blasting. Chemical cleaning can make the surface to a certain degree of cleanliness and roughness, but its anchor profile shallow, but also easy to spiral carbon steel pipe stacking environment pollution.
Reasonable use of means to clean the rust pipe fittings to ensure that a long time to serve the production and create more production efficiency.

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Thick-wall Steel Pipe

Thick-walled steel pipe, the pipe diameter and wall thickness ratio of less than 20 like that steel pipe known as thick-walled carbon steel pipe. Mainly used for petroleum geological drilling tube, petrochemical cracking tubes, boiler tubes, bearing tubes and automotive, tractors, aviation and other high-precision structural control.

The biggest difference between the thick wall steel pipe and thin-walled steel pipe is the wall thickness, in general, are thin-walled steel pipe belongs to drawing technology, and thick-walled steel generally use hot-rolled technology, if it is measured wall thickness / pipe diameter is equal to 0.05 that is a thick-walled steel pipe and thin-walled pipe watershed, wall thickness / diameter less than 0.05 that is a thin-walled steel pipe, thicker than the steel pipe, in use On, the thin-walled steel pipe used for pipe. The thick-walled mild steel pipe and more hollow parts used in the blank. Pressure and the use of important pipelines.

Thick-walled steel pipe is mainly used in water supply engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. For liquid delivery with: water supply, drainage. For gas transportation with: gas, steam, liquefied petroleum gas. For structural use: for piling, as a bridge; terminals, roads, buildings and other structural steel pipe.

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How to Produce the Steel Pipes?

There are two types of steel pipe: welded steel pipe and seamless steel pipe. Either type may be made of any alloy of steel that is formable. Welded tube requires that the alloy can be welded. Welded tubing begins as a flat strip. Seamless tubing starts in a melting furnace.

Tube Definition

A tube is a closed shape used to perform some structural function. The shape can be round, square, rectangular or whatever can be designed and manufactured for a particular application. Round tubes differ from pipes in the way they are dimensioned. A 1 1/2-inch round tube has a 1 1/2-inch outside diameter. A 1 1/2-inch round pipe has a 1 1/2-inch inside diameter. The reason being that the outside of tubes is important for structures, however the inside of pipes is used for fluid flow.

Welded Steel Tube

Welded steel tubing is made from either hot-rolled or cold-rolled steel that is provided to the tubing manufacturer in coils. The coil may be processed to remove scale, improve finish, amend heat treatment or in other ways to achieve the specified end product. The coil is then run through grooved rollers until the shape has been formed and the free edges are correctly spaced for welding.

The edges of the tube are butt welded together, generally with electrical resistance welding. The outside, and sometimes the inside, welding residue is then removed. The tube, which is at this point somewhat oversized, is then put through two semicircular rollers that bring it to its final outside dimension.

Seamless Steel Tube

The manufacture of seamless structural steel pipe typically begins in an electric arc furnace. The steel is then cast as an ingot or continuously cast as a bloom. The bloom is then rolled into a billet. The solid billet becomes a tube by being drawn over a piercing tool by two external rollers set at an angle to each other that move the billet. At this point a “rough” tube has been formed.

The rough tube is put through an elongator, in which three rollers and an internal mandrel shape the tube closer to its final outside diameter and wall thickness. The next step takes place at a reducing mill, where the outside diameter is brought still closer to its final size and the tube is made oval to ultimately improve its final finish. The rotary sizer is the last step in the basic seamless tube-making process. The rotary sizer restores the tube to a round shape and brings it to its final outside dimension.

Mechanical Processes

There are additional processes possible in the manufacture of welded and seamless tubing. The most common mechanical process is cold drawing. This is done by drawing the tube over a mandrel. The product is known as DOM (drawn over mandrel) tube. Cold drawing improves the physical properties, the surface finish and can tighten dimensional tolerances.

Heat Treatments

Various heat treatments may be used in the manufacture of welded and seamless tubing. These include annealing that improves the “microstructure” of the metal; normalizing that makes the tube properties more uniform and tempering that makes the steel more ductile.

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How to Deal with the Pipe rust?

Steel pipe derusting methods: 

Tools derusting 
Mainly use tools such as steel wire brush for surface grinding; it can remove loose or cock of oxide skin, rust, welding slag etc. the effect of Manual tools can achieve Sa3 level, and derusting power tool can achieve Sa3 level.  If the oxidized scale adherent firmly reach derusting steel surface, and the effect of tools derusting is not ideal, then it can not meet the anti-corrosive coating steel pipe construction requirements of the anchor grain depth pickling. 

Pickling derusting 
Generally use chemical and electrochemical two methods to do pickling, but pipeline corrosion protection only uses chemical pickling. They can remove oxide skin, rust, old coating, and sometimes can be used as retreatment after blast cleaning
Although chemical cleaning can to some extent make the surface clean and rough, its anchor lines are shallow, and this method easily cause environmental pollution.

Spray (cast) shoot derusting 
Spray (cast) shoot derusting, which is driven by high power electric jet with spray (cast) shoot blades to do high speed rotating, processes steel surface with abrasive like steel grit, steel shot, wire section, and minerals under the action of the centrifugal force .it not only can thoroughly remove rust, oxides and dirt, but also, under the hurl and friction of abrasive, structural steel pipe can still achieve uniform roughness needed. Spray (cast) shot, not only can expand after derusting physical adsorption of pipe surface, but also can enhance the mechanical adhesion between coating and pipe surface.
Therefore, spray (cast) shoot derusting is the ideal way for anticorrosion derusting. Generally speaking, shot peening (arenaceous) is mainly used for inner surface treatment, and peen-forming (arenaceous) derusting is for pipe outer surface treatment.

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The Application of Coating Steel Pipe

Coating steel pipe in large diameter spiral welded pipe and high-frequency welded steel pipe made of plastic coating on the basis of a maximum nozzle diameter 1200mm, can be coated with polyvinyl chloride according to different needs (PVC), polyethylene (3PE), epoxy resin (EPOZY) and other various properties of plastic coatings, adhesion, corrosion resistance, and can be resistant to acid, alkali and other chemical corrosion, non-toxic, does not rust, wear and impact resistance, resistance to penetration strong, smooth pipe not adhere to any substance that can reduce transmission time of resistance, to improve traffic and transportation efficiency, reduce delivery pressure loss. Solvent-free coating, no leakage of material, which does not pollute the transmission medium, in order to ensure fluid purity and health, in the range of -40 ℃ to +80 ℃ thermal cycling can be used interchangeably, not aging, without cracking, which can be in cold areas and other harsh environments.

Large-diameter coating steel pipe is widely used in tap water, natural gas, petroleum, chemical, pharmaceutical, telecommunications, electric power, marine and other engineering fields.

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Anti-corrosion Method of Coating Steel Pipe

Anti-corrosion coating steel pipe anti-corrosion methods are generally used anti-corrosion coating, under the following we to understand the knowledge about corrosion coating.

Anti-corrosion coating is uniform and dense coating to the metal coating in the pipe by rust on the surface, to cut off with a variety of corrosive media, is one of the most basic way steel corrosion. Steel pipe anti-corrosion coating increasingly using composite materials or composite structural steel pipe. These materials and structures should have good dielectric properties, physical properties, chemical properties and stability of a wide temperature range and so on.

1, the outer anti-corrosion coating: coating the outer wall of pipe types and conditions of use.
Wall corrosion coating: In order to prevent pipe corrosion, reduce friction, increase the amount of input applied to the tube wall and membrane. Coatings are commonly used in epoxy resin and polyamide curing epoxy amine coating thickness of 0.038 to 0.2 mm. In order to ensure a strong bond coating and the wall, the inner wall surface must be handled. Since the 1970s tend to pipe, coating the outer wall of the same material used for the tube, the outer wall of the coating at the same time.
Corrosion insulation coating: in the small diameter of the heat output of crude oil or fuel oil pipeline, in order to reduce the heat to the soil carbon steel pipe, the pipe insulation and corrosion with external composite layer. Commonly used insulation material is rigid polyurethane foam, for a temperature of -185 ~ 95 ℃. Soft texture of this material, in order to improve their strength, increase in the deposited layer of insulation outside the high-density polyethylene layer, to form a composite material structure, in order to prevent infiltration of groundwater into insulation layer.

2, such as the outer protection tube is polyethylene pipe, do not need anti-corrosion
Polyethylene odorless, non-toxic, wax-like feel, with excellent low temperature performance (the lowest temperature up to -70 ~ -100 ℃), good chemical stability, the ability of most of the acid-base erosion (oxidative nature of intolerance acid), not soluble in common solvents at room temperature, water absorption, but because of its slow as a linear molecule can be soluble in some organic solvents, and does not swell, excellent electrical insulation properties.

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Advantages of DSAW Steel Pipe

Advantages of spiral welded steel pipe: welded pipe production process is simple, high efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than the Longitudinal, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different diameters of pipe. However, compared with the same length of straight seam pipe, the weld length increased by 30 to 100%, and lower production rate.

The pressure fluid transmission DSAW steel pipe of  SY5036-83 is mainly used for transporting oil, natural gas pipeline; pressure fluid delivery SY5038-83 high-frequency welded steel pipes with spiral seam welded with high frequency lap welding method usedpressure fluid transmission spiral seam of high-frequency welded steel pipe. Bearing capacity of mild steel pipe, plastic, for easy welding and processing; generally low-pressure fluid transmission spiral submerged arc welded steel pipe SY5037-83, using double-sided automatic submerged arc welding or single-sided welding into the legal system for water, gas, The low pressure fluid such as air and steam SAW pipe.

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The Main Purpose of Coating Steel Pipe

Different industries and areas of corrosion in a pipe, spiral steel corrosion in concrete can be used to show the industry an important role and performance. Different industries have an important supply. Spiral steel pipe corrosion classification and use: according to different production methods it appropriate classification. According to different production methods can be divided into hot-rolled pipes, cold-rolled, cold drawn tubes, squeeze carbon steel pipe. Tube extrusion method is about to heat a good squeeze on the closed cylinder, spiral steel pipe corrosion there are many different production methods. Perforated stick together with the extruded rod movement, the extrusion die from the small hole in the extrusion. This method can produce smaller diameter steel pipe. Spiral steel pipe corrosion can be divided into different categories and types, different types can be used in actual play an important role and nature of Eng, according to the normal use of methods and principles for use, to ensure that the use of the contribution. Required the use of cold-rolled, cold drawn or the combination of the two methods.

In roller cold rolling mill is usually carried out on Ruoyu get smaller and better quality of spiral steel pipe corrosion. Steel tank in the tapered hole and fixed head consisting of a conical hole in the ring rolling. Cold-drawing is usually 0.5 100T single chain or double chain drawing machine on. Cut into desired length, usually in the hot-rolled  coating steel pipe mill on automatic rolling production. Solid tube and remove surface defects upon inspection. End to end surface of the perforated tube-centering, and then sent to the furnace heating, punch on the punch. Perforation while continuing to rotate and move, roll, and the role of the head, the tube gradually formed within the cavity, said capillary. Spiral steel pipe corrosion and then sent automatically to continue rolling machine. Finally after all the whole entire wall thickness were, after sizing mill sizing, specification. The use of continuous rolling pipe mill producing hot-rolled thick wall steel pipe is more advanced methods.

The use of spiral welded steel pipe corrosion: as to withstand the liquid pressure, corrosion is extensive use of spiral pipe. There are special-purpose seamless pipe spiral steel pipe boiler corrosion, geology and oil with anti-corrosion steel pipe with a spiral spiral steel and other corrosion. Supply three types according to different uses: a chemical composition and mechanical properties according to the supply; b supply by mechanical properties; c according to pressure test supply. By ab class supply pipe. Pressure test must be conducted. Spiral steel pipe for general use by the general corrosion of carbon steel, low alloy steel or alloy steel rolling, yield up, mainly for the transmission fluid pipe or structural components.

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A Comparison Between HFW and Contact Welding for API Steel Pipe Production

There is a history over 50 years of using high frequency welding API steel pipe technology(HFW) and contact welding API carbon steel pipe technology for API steel pipe production, both of the two methods have their advantages and disadvantages. When it comes into a production of an API steel pipe larger than 460mm, it is important to balance the two methods. With the continuous increase in the wall thickness and diameter of an API steel pipe, welding process selection will be more difficult.

Some people think that high frequency welding API steel pipe technology has better quality than contact welding API steel pipe technology. In fact, the welding is difficult to distinguish between these two methods in API steel pipe production. Compared with contact welding API steel pipe technology, the main advantage of HFW is the use of induction coil does not produce the "arc burns on the mild steel pipe". For the oil and gas industry pipe "arc burn" must go through a separate operation to remove, in order to meet the requirements of the specification of API steel pipe. When it comes to reel-to-reel welding procedure, the arc burn is more obvious. The contact welding can also produce no arc burn in cautious setup and operation process. For API steel pipe production drawing very high performance materials, contact welding API steel pipe technology has the advantage in the short welding area, while high frequency welding API steel pipe technology has a longer area. If the strip is formed not under control in the longer welding area, the welding quality of API steel pipe will be seriously affected.

High frequency welding API steel pipe technology is very suitable for reel-to-reel welding procedure, large diameter for the loopers are almost applied installed in the technology. The reason is set to wear material, contact easily lifted away from the strip. With the application of high frequency welding API steel pipe technology, steel from the end part can be carried out in several inches, each roll strip almost completely is made and strip length tube, so that the quantity of waste will be a minimum. The length of API steel pipe directly affected by the strip length, which makes the high frequency welding API steel pipe technology feasible, and can obtain the maximum production capacity of pipe production unit.

On the one hand, when the unit is continuous production, contact welding API steel pipe technology has a high work efficiency. But if the edge and the work coil to wear material in the collision, the work coil is likely to be damaged. On the other hand, most induction welding production requires induction of coil matching with the contact welding API steel pipe technology in a more expensive price. In API steel pipe market which is the most important factor in determining the success of a production line. To conclude, when producing API steel pipe in high frequency welding API structural steel pipe technology, it is more effective than contact welding API steel pipe technology, especially when it comes to reel-to-reel welding procedure.

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Primary Introduction of Carbon Steel Pipe

There are more types of welded carbon steel pipe, which takes the place of seamless carbon steel pipes in more and more fields due to the low cost and effective production. Here will give you the primary introduction of welded steel pipe.

Welded steel pipe Refers to the steel pipes made by curved steel band or steel plates in round, square and etc shape, and then be welded with weld joints on the surface. The raw materials are steel plate or steel band. Separated with different types of welding technique, welded steel pipes can be divided into arc-welded steel pipes, high frequency or low frequency resistance weld pipes, gas-welded steel pipes, bundy pipes and etc. Arc-welded steel pipes are mainly used for oil drilling and machine manufacturing. Rather, continuous welding of pipes can be used for water gas pipeline. Besides, this type of pipes with large size is used for transportation of high-pressure oil and gas. Helical weld pipes would also serve as tubular piles and piets. As it mentions before, we can also separate different types of welded steel pipe by the type of weld joint. There are helical weld pipes and longitudinal welded pipes, two pipes.

As for DSAW steel pipe, the manufactory technique is kind of simple with low costs and high production efficiency. Due to these factors, the development of longitudinal welded pipes is very fast, while helical weld pipes have better strength than longitudinal welded pipes. The best advantage of pipes is that they can suit for almost all width of steel bands. By using this welding technique, we can produce large size pipes with narrow steel bands. In this way, we can produce various size pipes with steady width of billets. However, compared with longitudinal welded pipes, the length of welded steel pipe develops from 30% to 100%. At the same time, it takes much longer to produce similar size of welded steal pipes. As a result, small size often uses longitudinal welding. While large size often uses this kind of weld. As the development of oil and gas pipes is in high speed, there is great need of welded steal pipes. The 12th five-year plan supports that the totally length of oil and gas pipelines is going to be more than 150 thousand kilometers till 2015, increasing almost 30% than 2010.

So the future of structural steel pipe is very bright. It is estimated that the annual need of SSAW is more than 5 million tons. And the annual need of LSAW is more than 2 million tons. During the 12th five-year, thanks to the advantage of welded steel pipes. There would be more steel pipe markets for welded steel pipes. According to my introduction of Welded steel pipe's use and development, I believe you have known more about it. Sincerely hope it is useful for you.

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Know More About Welded Steel Pipe?

There are a lot of kinds of carbon steel pipe in the world. Welded steel pipe is just one kind. the weld quality is improved, different specifications of welded steel pipe are increased over the years. Instead of seamless steel pipe, welded steel pipes become popular in more and more areas.

Classification
So far, welded steel pipe has a lot species. Thus, it is significant to classify welded steel pipes. It can be clarified by application, the mode of production, the cross-sectional shape, wall thickness and the end shape. The longitudinal and spiral welded steel pipe we also talked about is clarified by the form of the weld points. Spiral welded steel pipe can use the narrow billet to product the large one. You can also use the same width of the billet to product different diameters. However, compared with the same length of longitudinal welded steel pipe, its weld length will increase 30% to 100%. Also, it has lower production rate. Thereby, DSAW steel pipe mostly uses the small diameter pipe, and the large one is used by spiral welded steel pipe for the most.

Application
We may not be familiar with welded steel pipes. But it is very common in life. It can be used to transport low pressure fluid, such as conveying water, gas, air, oil and heating hot water or steam and other low pressure fluids. In this case, its raw materials are usually soft easy-welded steel. Welded steel pipes can also be used to transport mine liquid, like mine air pressure and drainage. Some furniture, toys and lamps can also be made up by welded steel pipes. If we are good at discovering, we can learn everything everywhere in life.

Testing
The test of welded steel pipe needs to attract enough attention. Firstly, test raw materials of welded steel pipes. The quality of raw materials is the key to ensuring the quality of the pipe. Therefore, all raw materials must be inspected prior to use. All materials can only be used after passing. Secondly, test geometry of raw materials. All products have a certain size requirements, so as the welded steel pipes. The strength, the width, the deviation and others should meet the stipulated requirements. Finally, test the exterior and internal defects. The exterior defects include camber, bending waves and waves wrinkle, uneven thickness and so on. The internal defects have shrinkage, laminated, non-metallic inclusions and segregation. All these defects may result in failure of structural steel pipe.

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The Ultrasonic Testing System of API Oil Steel Pipe

Automatic ultrasonic testing is refers to the use of mechanical devices automatically move probe to achieve automatic scan of workpiece tested in the process of moving to use different ways to realize different ultrasonic wave type. Such as the different coupling method for structural steel pipe automated testing. The records of the results of the test of the workpiece can be automatically recorded in a particular medium, such as the pen type record of paper tape, electrical, computer storage devices, etc.), you can also automatically tag (painting, printing, etc.) on the workpiece. It also can do automatic sorting of qualified and unqualified artifacts and so on. Automatic ultrasonic testing system usually also has the monitoring device (such as oscilloscope, flaw detector display screens and computer monitor screen, etc.), facilitate testing personnel according to signal detection monitoring system work is normal. Automatic ultrasonic testing system can be divided into two categories:

1. The on-line automatic ultrasonic testing system of API mild steel pipe
This is an automatic production line process (station), it is not used only to judge the workpiece tested qualified or not and automatic sorting or tag spray (standard) and the detection speed, detection system of the continuous running time, it also can judge the work environment conditions (such as high temperature, vibration, noise, etc.) of adaptability and detection systems to protect themselves, etc.

2. Offline (not online) automatic or semi-automatic ultrasonic testing system which is in the process of production as a separate the inspection process, it can be divided into two types of automatic and semi-automatic.

1) Off-line automatic ultrasonic testing system
All except sensitivity adjustment and the machine maintenance work steps, such as front-rear and defect alarm and record, tag, are all depend on the device itself automatically, such as the many domestic large enterprises currently have been using the application of the steel plate automatic ultrasonic testing system

2) Offline semi-automatic ultrasonic testing system of API steel pipe
Part or parts of API steel pipe working procedure needs to be done with artificial, such as checked material defects or workpiece loading and unloading and loading, tags, etc. For example in the aviation industry to the turbine and compressor disk disc parts and parts of semi-automatic water beam type ultrasonic testing system. With the development of science and technology progress, the domestic ultrasonic testing is most used the API steel pipe automated testing, automatic detection of main advantage is: Due to the ultrasonic probe and checked materials or workpiece automatically relative motion, compared with manual testing, it can guarantee acoustic coupling performance is stable; It can do rapid detection of bulk API carbon steel pipe materials to conduct a comprehensive inspection of large area, which has the features of high speed and high efficiency; It can automatically record test results.

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The Long History of Welded Steel Pipe

Over the last decade, welded steel pipe has been developed and improved so that welded steel pipe has a long history and welds can be made with consistent high quality and high productivity. And such advanced welding systems are available from several major pipeline equipment suppliers. As a matter of fact, the development of welded steel pipe can be summarized in different periods. In the 1930s, the first mechanized arc welded steel pipe was developed with a 35 degree arc with the help of angle weld preparation, stringer beads, and a narrow groove weld preparation in order to achieve side wall penetration. To be more specific, the welding head of the welded steel pipe was made with two bugs clamped on either side of the pipe and turned downwards from the 12 o'clock position to the 6 o'clock position. In the 1960s, internal welding machine was invented and used in the making of the welded steel pipe. Internal welding machine allow more than three welding torches to operate at the same time.

And external root welding techniques were developed during the same period with the advent of internal copper ring. In the 1970s, root welding techniques were used to produce the  carbon steel pipe. Previously small diameter pipes and closing welds in larger diameter lines could not be internally welded without some sort of backing. The introduction of modern power supplies with control of metal transfer has made possible the internal welding without any backing. For example, a type of surface tension transfer process can be used with a root gap to achieve high-quality root runs, which is operated by detecting both the short circuit and the incipient rupture of the metal ridge. Better quality welded steel pipe can be manufactured thanks to the adjustable welding currents. And a stable transfer can be achieved at low-heat input and with little or no spatter.

According to the long history of welded steel pipe, the original welding systems of welded steel pipe make use of torches and wire feeds. In the 1980s, a dual torch welding system on one welding bug was introduced, which has been extensively used in a number of structural steel pipe manufacturers. To be more specific, the efficiency of the welding processes determines the properties and specifications of the welded steel pipe required by the customers, which takes on increasing significance as the wall thickness and diameter of welded steel pipe increase over the years. The introduction of the gas metal arc welding process offers further possibilities to increase the productivity of welded steel pipe. This special process typically uses a single torch with two contact tips to feed two wires into a single weld pool. Thus high welding speeds as well as excellent welding results can be assured. In some case more than two tandem torches can be used on one welding bug so as to further reduce the welding times while manufacturing DSAW steel pipe.

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How to Find Reliable Welded Steel Pipe Operators

There are a variety of safety regulations concerning the operation and the installation of the welded steel pipe. To begin with, operators of the carbon steel pipe line are expected to implement and maintain a corrosion control program for their piping system. In general, the procedures consist of a series of installation, operation, and maintenance activities during different periods of time. As a matter of fact, for different welded steel pipe lines, the procedures may vary a great deal. More importantly, professionals well qualified in pipeline safety control methods are needed to carry out these procedures in an effective manner. For instance, operators or contractors of the welded steel pipe lines may hire qualified personnel to develop and carry out a safety control program from an array of educational institutions as well as scientific groups.

What is more, there are many consultants and experts who specialize in the safety of the mild steel pipe lines. Another source is an experienced pipe line engineer or technician who has worked in the piping industry for more than ten years. With their knowledge and skills, such experts of the welded steel pipe lines may be able to implement safety protection for small welded steel pipe operators, or refer them to local qualified engineers. Moreover, it is recommended that operators the welded steel pipe lines first contact the local piping industry association to see if any engineer or technician can be dispatched to do the job.

What is more, these welded steel pipe operators not only strictly conform to the safety regulation standard but also has a long tradition of excellent service and product quality. As a matter of fact, some welded steel pipe operators are capable of producing full line welded steel pipes ranging from one quarter to 12 nominal sizes according to ASTM standards. And the applications of their structural steel pipe can be adapted to the customers' requirements. For instance, ASTM A55 welded steel pipe is in general used for mechanical and pressure applications. It can also be used in steam, water, gas and air lines. In addition, more than three hundred different combinations of welded steel pipe finish, end treatments and lengths are available with these operators.

For instance, they offer a wide range of surface finishes, including black, bare, galvanized, uncoated, pickled, and oiled. And such end finishes as roll groove and cut groove are also available. Reliable manufacturing environments and techniques ensure that all the welded steel pipe products will conform to the ISO Quality Management Systems at minimum. More important, some welded steel pipe operators are strategically located the first-tier cities in different countries so that they carry a large inventory and can deliver the welded steel pipe products quickly.

Importance of Right Filler Metal for Welded Steel Pipe

When welded steel pipe is in the process of welding, there is a big potential threat which is called hot cracking that occurs immediately upon completion of the weld. Because of its larger grain structure, this material is particularly susceptible to the defect. Right filler metal, as well as proper heat input and post-weld cooling, is vital to cracking prevention and corrosion resistance coating steel pipe during the welding process.

Welded steel pipe should be matched with right filler metals based on their chemical and mechanical features. Luckily, it is easier for this kind pipe to make this match than many other materials. The grade of welded steel pipe that will be used for application can be affected by the intended service condition, and the grade of material has a great influence on the filler metal selection. For example, it is better for welded steel pipe with 304L to choose filler metal with American Welding Society, but 316 welded steel pipes should be matched with a 316L filler metal. Sometimes, we can also have to weld steel pipe to carbon steel, so a 309 grade filler metal is proper.

The final weld of the welded steel pipe can be integrated because the filler metals contain alloy. In addition, we usually prevent the pipe from corrosion by chromium and molybdenum. Molybdenum can also be useful for good high temperature and if weld strength needs to be increased, the nickel may be useful. The addition is not only used to maintain weld poop fluidity, but also stabilize the amount of austenite in the weld, which will in turn be helpful for refining the grain structure of the weld and crack resistance.

One kind of stainless steels which is known as the ferrite number is popular among engineers and designers. The ferrite number can be applied to measure the amount of ferrite versus austenite in the structure of the material. The ability of carbon steel pipe to resist cracking and corrosion can be indicated by the ferrite number. Generally, we use the chemistry of the material to determine the amount of ferrite present. When welding steel, it usually needs to reach a maximum ferrite number, but some special applications may require higher ferrite numbers.

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The Typical Process of the Welded Steel Pipe

The ERW steel pipe, which is the Electric Resistance Welded steel pipe, begins as a coiled plate of steel with appropriate thickness and specific width in its processing. This kind of welded steel pipe is cold formed. In the manufacturing process, pull the ribbon through a series of rollers to form it into a cylindrical tube. An electric charge should be used to heat the edges so that they can be welded together when the edges of the cylindrical plate come together. The electric resistance welded steel pipe can be produced at a high speed in continuous lengths up to 115'. The wall thicknesses and outside dimensions that the pipe produces is uniform, and the electric resistance welded pipe can be made in a variety of specifications. However, sometimes this kind of pipe needs minimum tonnage so that it can be set up on a specific size and has long lead times.

The name of the DSAW steel pipe comes from the process that the welding arc is submerged when it happens. When the welding temperatures are heated, the flux is useful for preventing the weld area from impurities in the air. Only when the inside welds and outside welds are performed and the welding be accomplished in separate processes. Therefore, the pipe then can be looked as double submerged arc welded. This kind of process is suitable for three common types of pipe: U&O Press, Rolled and Welded, Spiral weld.

The spiral welded steel pipe, which is in a spiral form, has a DSAW seam the entire length. We can apply the angle of the steel that is de-coiled against the forming head to determine the outside diameter of the spiral welded pipe. The angle that is used is more acute, and then the diameter that is determined will be greater. The spiral structural steel pipe can be used in more places because of the production of large, hot rolled coils of sufficient width and the development of dependable non-destructive testing methods. The lengths up to 115 feet in either ID or OD dimensions up to 144 inches are suitable for the roll of the spiral welded pipe. The contractor may have an advantage of short term changes because of the slow manufacturing process. However, the slow manufacturing process may have a bad effect if the large tonnages are needed with a short lead time. The spiral welded steel pipe has limit specifications.

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Special Filler Metals of Welded Steel Pipe

The first one is flux-cored wires. When welding out of position on thick-walled welded steel pipe, it is better to choose gas-shielded flux-cored wire to achieve high deposition rates. This kind of filler metal can weld out of position without a special power, and the flux coating on the wire can be considered as a dam which can hold the molten weld pool in place. Therefore, the flux –cored wires are useful for improving productivity. However, there are some disadvantages when using the flux-cored wires in the welded steel pipe. Higher levels of smoke may be produced and a slag may be generated by the wires. Then both between passes and after the cap pass, the welding operators will need to chip or grind in, which in turn leads to greater downtime for clean up.

The other kind is metal-cored wires. When welding structural steel pipe, the metal-cored wires are accepted more and more widely. The available diameters of the metal-cored wires range from 0.035- to 1/16-inch. In order to weld out of position, the pulsing or advanced short-circuit processes, with which the metal-metal wires can be applied to weld from root to the cap, are needed by stainless steel metal-cored wire. What is more, the welded steel pipe with these kinds of wires can provide greater productivity. One disadvantage to metal-cored wires is their cost. Though the metal-cored wires are more expensive, the productivity and quality improvements outweigh the cost.

The third one is solid wire. When welding thicker-walled welded steel pipe, we usually choose solid wires which must use a special power source to weld out of position. If the welded steel pipe is being rotated, these filler metals can be used to weld fill and cap passes in the flat or horizontal position. In addition, solid wires are useful for welding out of position for root, fill and cap passes. However, for welded steel pipe, it is more difficult to match the chemistry. Then the availability of the filler metals may be influenced.

The last one is DSAW steel pipe. SMAW (shielded metal arc welding) electrodes are of great importance for welded steel pipe because of the availability and familiarity of the filler metal. However, compared with other filler metals, the SMAW electrodes are slower and less efficient.

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Utility and Usage of Carbon Welded Steel Pipe

As the name implies, the main constituents of welded steel pipe is steel and carbon. Because of to the composition of these pipes, they are nicely suited for commercial and geothermal applications due to the reality of the tensile power they offer. These pipes are seamless and for that reason confirm to be of outstanding electricity as essential oil pipelines or as transporters of other fluids. The broad distribute utilization of the seamless carbon steel pipes is due to the reality of the composition and the advantages that they offer. These pipes are an apparent selection for heavy requirement commercial performs due to the tensile power of these pipes. Be it the making or mammoth ships, or even the performing elements of massive machinery, these pipes endure the stress nicely sufficient to invoke self-confidence in its end users.

When security and durability are of concern, these welded steel pipes pass the check with elan. The carbon steel pipe are resistant to vibration, shock, water stress, fire, and heavy force. For that reason any framework constructed of these pipes is considerably safe and sound from organic calamities like hurricanes, earthquakes, and tornados, fire and lightning, and also harmful floods. Steel is the most beneficial compound to resist cracks, so there is no dread of the pipes separating in circumstance of heavy stress on them. If a single decides to create frameworks underground, utilizing these pipes could be a sensible choice, as they will not rot as opposed to wooden.

The pipes are also utilized as transporters of fluids due to the reality the mixture of carbon and steel offers go up to an extremely ductile, elastic, and malleable compound. This creates it simpler to produce pipes that are slender, yet long lasting. They are as little as 1/8 inch external diameter to as huge as 72 inches external diameter. One can pick from carbon steel pipes of different diameters to transport fluids like essential oil, petroleum, organic fuel for example. Getting seamless, these pipes do not leak as there are no joints and fluid transport can be performed without dread any sort of leakage that could end result in an automobile accident. The reality that carbon steel pipes can be created slenderer than welded steel pipe created of other materials like copper creates it evident that the price of manufacturing these mild steel pipe will be much less than all those of its rivals. Yet, the advantages of these pipes outshine the relaxation that is out there in the industry. It is powerful, lengthy lasting, leak evidence, and separate cost-free. So various capabilities decrease the require to replace the pipes and this in turn decreases the price a single would have to regularly incur in this kind of scenarios.

Using welded steel pipe is one more way to preserving a cordial romantic relationship with dynamics? The structural steel pipe is dynamics' product or service, and steel manufacturing has also grown to be natural environment friendly. Following total utilization, steel is recycled and reutilized. This procedure creates it quick to retain the earth clean up.

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