Development Tendency of Steel Pipes

According to analysis of relevant experts and database, the price of carbon steel pipe is expected to rebound this year. China has taken action to enlarge the demands of consumption of steel, for instance, the country construct 36 million sets of affordable housing and all kinds of shantytowns transformation housing, the national railway infrastructure investment plan has been adjusted for 4 times, increasing from 406 billion RMB to 516 billion RMB, water conservancy engineering like South-To-North Water Diversion Project has been under construction. These are a series of methods stimulating domestic demand introduced by government. And the government vigorously supports steel the main industries with expectations that it won't decline again. Demand of engineering construction for pipeline is also insignificant, owing to the state investment in the projects such as housing and engineering, the demand for steel pipes also increases rapidly.

Last year, China's steel pipe exports kept a high level, which is expected to continue in 2015 all the year around. Considering it is difficult for the price of carbon steel pipe to rise sharply, it is expected that export growth will remain stable in 2017. Besides, private investment projects become more and more popular and can be seen everywhere with certain scale which stimulates demand of steel pipe market as well. So in situation of the national macroeconomic regulation and control and the construction of private enterprise investment, the development situation of steel pipe is considerable in 2017.

The Development of Galvanized Steel Pipe Industry

Rebar futures fell on Monday is the reaction that markets against the "New Deal", is likely to be the end of the rebar futures fell, if it can return to above 60 per line on the next trading day , it’s very likely that hot dip galvanized structural steel pipe will increase. "Analysts said, the stipulation of the housing market in the" New Deal "about value-added part of individual real estate sales collecting 20% income tax will reduce the supply of second-hand housing market, force the house-purchase demand tilt to the newly-built house demand, thereby it will promote the rate of operation of new house, and it will benefit rebar. The reporter get it from a house agent in Shanghai, after introducing "New Deal", the second-hand housing in Shanghai sales well, both buyers and sellers hope to finish buying and selling before implementing the detailed rules . And after the "New Deal" implemented, the transaction of new house is expected to expand further. From the beginning of July, There are several buildings under construction in Jiangsu, Zhejiang and Shanghai. In the long run, the introduction and implementation of the regulations of "New Deal" will benefit the construction of urbanization.

Recently, although downstream terminal purchasing rose again slightly, inventories fell, the stability still remain to be seen, and real estate, automobile, shipbuilding and other industries didn’t recover obviously. 

As for how long the current steel prices rally can last, and whether it presages have formed steel price turning point or not, experts believe that businesses should not be too optimistic. Jiangsu Shagang Group Co., Ltd. raised more conservative in mid-march, the policy of Baosteel in April is out of the expected tone that maintain stability and reduce price. The pricing policy of galvanized mild steel pipe steel is somewhat does not conform to the rules, the intention of waiting the bearish market is relatively obvious. Perhaps it is an action taken base on cost reduction of iron ore and other raw material. Just in order to get more orders, but obviously, it’s more difficult for Tianjin market to judge lately. 

There are 61778 new projects under construction during the first three months of this year, increased by 8516, compared with the same period last year. Manufacturing PMI picked up for three consecutive month-on-month and reached 53.1 in March, These all showed seasonal demand become better and provided the safeguard for the rising of steel mill. Since March this year, the speed of the steel reduce inventory is relatively slow. At present, five varieties of inventory have a total of 17.45 million tons, the maximum fell by 8.2% compared with 8 weeks ago. Under the circumstance of the original inventory declining relatively slowly and resources still increasing, supply pressure will appear again in future. 

Whether the iron ore spot trading platform can be pressed back to iron ore pricing right or not, experts said that the opening of the trading platforms added a channel for iron ore trading, but had no effect on iron ore supply and demand structure, and high-pressure alloy pipe pricing right is mainly determined by the relationship of iron ore supply and demand. At the same time, the platform also accelerated the advance of the process of spot iron ore trade, and made steel mills more difficult to control raw material cost .It’s still worrying for galvanized mild steel pipe price factory to improve their profit.

Industrial Demand for Oil Casings

Oil casings are the lifeline which keep oil wells running. Oil casing needs to bear the complicated force coming from pulling, pressing, curving and twisting under oil well, because of the different geological conditions. Therefore, oil casing needs to have high quality. Once oil casing is damaged for some reasons, it may lead to reduction of output for oil well, even become useless.

Oil casing is a kind of pipe with large diameter, which immobilizes the wall and pit of oil and gas well. Oil casing is used to insert into the oil pit and immobilized with cement, to prevent the well from stratum and collapse, make sure the circular flow of the drilling mud for drilling.

Oil casing is carbon steel pipe that is used to support walls of oil and gas well and assures the operation in and after the drilling process. We need to use several layers of casings based on the different drilling depth and geological conditions for each oil well. We should use cement to immobilize the oil casing after being put in the oil well. Oil casing can't be reused, it belongs to disposable material, which is different from oil pipe or drill pipe. So the consumption of oil casing makes up 70% of the whole oil pipes. Oil casing can be classified into conductor casing, surface casing, intermediate casing, production casing according to its using.

After nearly 20 years' effort, China's oil casing production develops from nothing, low price to high price, low steel grade to API series and to specific requirements, our oil casing products nearly reach international level from quantity to quality. China's oil casing products have taken up over 80% of domestic market and become net export for years in a row.

According to the analysis and forecast report of production and sale requirement and investment of China OCTG industry from 2013 to 2017, Chinese crude oil output reached 204 million tons in 2011, which has increased 0.32% compared with 2010. Gas output got to 102.531 billion cubic meters, increased 6.9%, which reached the highest record. We are still in the rapidly developing stage of urbanization and industrialization, the oil demand in the coming years is expecting to grow about 4%. The increasing demand for oil promotes petroleum drill and exploitation equipment in China.

The demand for OCTG casings no longer focuses on the east of China from geographical view. And if we see it from the trend of oil-gas field, initially develop from east to west, that is, from Daqing, Liaohe, Shengli to Sichuan, Xinjiang. Besides, it is going to develop from land to mudflat, epeiric sea to deep sea. In addition, with the increasing drilling depth, the drilling work is going to be more complicated, which requires more for OCTG casings.

Installation of DSAW steel pipe

1. Repair mouth
In order to ensure the quality of the welding, the welding is carried out before the full inspection and correction, so that the pipe end, bevel angle, blunt edge, roundness, etc., are in line with the requirements of the interface size, individual steel pipe needs In the field to do groove processing, the use of gas welding cutting, remove the slag and then grinding with a grinding wheel.

Counter operation procedures are: check the interface connector size → clear chamber → determine and adjust the longitudinal seam of the steel pipe staggered position → the first structural steel pipe straight → adjust the gap size of the counterparts → leveling the mouth → straight → straight line → spot welding

2. Welding
Interface welding using arc welding, once down the base, two times to survive, each weld are welded once, each layer of welding lead-off arc to be staggered.

A. Pipe joints should be first before the mouth, slag, tube end of the groove angle, blunt edge, clearance, should meet the specifications; not in the gap between the gap welding or welding method to narrow the gap welding.
B. The mouth should be flush with the wall, the length of 300mm long ruler in the order of the inner wall of the interface in order to close the wrong port to allow partial inspection should be 0.2 times the wall thickness, and not more than 2mm.
C. The position of the longitudinal and circumferential welds shall meet the following requirements: The longitudinal weld shall be about 45 ° from the semicircle of the vertical line of the DSAW steel pipe; the welded seam of the reinforced steel pipe and the reinforcement ring shall be in the longitudinal direction Weld staggered, the spacing should not be less than 100mm; reinforcement ring pipe section of the circumferential weld should not be less than 50mm; pipe any location shall not have cross-shaped weld.
D. When positioning welding, the positioning of all weld pads (or grades) should be the same as the official welding, but the electrode diameter optional fine. The welding current of the positioning weld should be chosen to be larger than the formal welding, usually 10% -15% to ensure penetration.
E. Carbon steel pipe welding: weld quality must meet the relevant provisions of GB50268-97 4.2, the weld should be smooth, uniform width, root penetration, no obvious bump defects and undercut phenomenon, weld reinforcement should be higher than the tube Face about 2 mm, weld the edge of the groove 2-3 mm.
F. Pipe and flange welding, the pipeline should be inserted into the flange two-thirds, the flange and the pipeline should be vertical, the two coincides with the axis.

Piling Pipe

Piling Pipe is widely used in coastal, river, lake area. Offshore deepwater terminal project in the country have also been large-scale construction in coastal areas, and as a major deep-water dock pile bearing capacity, generally use the large diameter spiral weld pipe, in addition, bridges, roads, high-rise building needs piling pipe etc.

Piling pipe weld surface shall not have cracks, broken arc, craters and holes and other defects, the presence of these defects allow the welding seam defects allow grinding or repair. Allow the structural steel pipe weld steel head, steel allow docking with two pipe sections together, submerged arc butt welding or manual welding process can be carried out. Production of steel piling mainly use the double submerged arc technology. A first advantage of using the double submerged arc technique is completely automated; The second advantage is conducted under submerged arc welding, the heat exchange and protection of its relatively strong performance, high quality welding out; the third advantage is the automatic submerged arc welding arc welding flux can be used under high-current, high welding efficiency. 

When piling, as a result of pile to soil compaction effect, first into the level of pile after pile was caused migration and displacement or push and shove by floating pile vertical extrusion drawing; then pile into hard to reach design elevation or buried deep, causing uplift and squeeze the soil, cut pile is too large. When the group piles, in order to ensure the quality and progress, to prevent damage to surrounding buildings, according to the intensity of the pre-piling structural steel pipe, pile size, length and pile frame is easy to move and other factors to select the correct piling order. Common piling order generally following categories: conducted in one direction by the side from the middle to be symmetrical in both directions, from the middle to four weeks. 

Perspective: Steel Technology Development in Ten Directions

To enhance the competitiveness of China's steel industry, we should grasp the direction of iron and steel technology development. As a seamless steel pipe, DSAW steel pipe, spiral steel pipe, galvanized pipe, scaffolding, stainless steel pipe and other products production service manufacturers, Shinestar Group believes that the next 5 to 10 years, China's steel technology development has the following 10 key directions:

The first is green, can be recycled steel manufacturing process technology. To high-quality, efficient, energy saving, environmental protection, low cost as the goal, through the steel process structure optimization and material flow, energy flow, information flow network integration construction, the key technology in-depth development.

The second, low-carbon steel manufacturing technology. Including efficient energy-saving emission reduction and cleaner production technology, scrap recycling process of fine research, alternative energy non-carbon metallurgical technology.

The third, efficient resource development and comprehensive utilization of technology. To improve the comprehensive utilization and resource recycling, the development of the associated components and tailings resources of the comprehensive utilization of technology.

The fourth is efficient, energy saving, longevity comprehensive smelting technology. Including blast furnace high pressure, high temperature and other technology, blast furnace expert system application technology, the development of practical high-grade refractory technology.

The Fifth is efficient, low-cost clean steel production system technology. The focus is to further study the multi-process "dynamic - ordered" "continuous - compact" "collaborative - stable" operation as the core of the clean steel platform system technology to achieve the whole system more efficient, low - cost operation.

The sixth is the high performance, low cost steel material design and manufacturing technology. Mainly include: low-cost, high-performance micro-alloying technology, high-grade special steel profiles, high-quality alloy steel production technology and application, molding, corrosion and other processing technology.

The seventh is high precision, efficient rolling and heat treatment technology. Mainly include the following common technology: high-precision rolling technology, a new generation of controlled rolling and cooling technology, headless and semi-endless rolling technology and long green manufacturing technology.

The eighth is the composite material manufacturing technology. Based on the iron and steel materials of composite materials manufacturing The main application of machinery, explosion, explosion / rolling and other traditional composite method, low production efficiency, variety, poor quality. Need to further research and development of high efficiency, high interface strength, special purpose composite materials, and get engineering applications.

The ninth is for the whole process of quality control of the integrated production technology. To carry out a new generation of steel production process control technology research to solve the control system in the production batch between the varieties of the adaptability between the specifications, a substantial increase in product quality under the control of the quality and stability.

The tenth is the information, intelligent steel manufacturing technology. Mainly include: large-scale equipment, intelligent embedded software development and application, key testing, testing equipment and data acquisition and analysis system.

As a member of the iron and steel industry, Shinestar Group will grasp the key development direction, strive to produce more technical content of seamless steel pipe, straight seam welded pipe, spiral steel pipe, galvanized pipe, structural steel pipe, stainless steel pipe and other products, improve enterprise's core competitiveness.

Mild Steel Pipe

Mild steel pipe refers to the content of less than 0.25% carbon steel because of its low strength, low hardness and soft. It includes most of the part of ordinary carbon steel and high-quality carbon structural steel, mostly without heat treatment used in engineering structures, some carburizing heat treatment and other mechanical parts required for wear. Mild steel pipe annealing organization ferrite and pearlite is lower its strength and hardness, ductility and toughness. Therefore, the cold formability is good and can be crimping, bending, punching and other methods of cold forming. Like that mild steel pipe has good weldability. Carbon content from 0.10 to 0.30% of mild steel is easy to accept all kinds of processing such as forging, welding and cutting, commonly used in the manufacture of chains, rivets, bolts, shafts, etc. 

Ordinary mild steel pipe is for the production of building components, containers, tank, furnace and farm machinery. Quality mild steel pipe is for making car cab, hood and other deep-red products; also rolled into bars, strength requirements for the production of mechanical parts. Before using mild steel pipe is generally not by heat treatment, the carbon content of more than 0.15% by carburizing or cyanide treatment, used to require high surface temperature, wear good shafts, bushings, sprockets and other parts. Due to the low strength of the low-carbon steel, use is restricted. Appropriate to increase the carbon content of manganese and add trace vanadium, titanium, niobium and other alloying elements, can greatly improve the strength of steel. If you reduce the carbon content of the steel and add a small amount of aluminum, and a small amount of boron carbide forming elements, you can get ULCB set high enough intensity, and maintain good ductility and toughness.

Low carbon content of mild steel pipe is very low hardness and poor machinability, normalizing process may improve machinability. Mild steel pipe tends to have a greater timeliness, both quench aging tendencies, as well as a tendency to strain aging. When the rapid cooling from a high temperature structural steel pipe, ferritic scraping carbon, nitrogen saturation, it can also slow the formation of iron carbonitride was at room temperature, and thus the strength and hardness of steel, the lower the ductility and toughness, a phenomenon called quench aging. Even without quenching and low carbon air cooling will produce aging. Produce large amounts of low-carbon steel by deformation dislocations ferrite from carbon, nitrogen atom elastic dislocation interactions, carbon, nitrogen atom reign gathered around the wrong line. Such a combination of carbon and nitrogen atoms and the dislocation line is called the Coriolis-year-old air mass (Ke lop air mass). It will increase the strength and hardness of steel while reducing ductility and toughness, a phenomenon known as strain aging. Than quench aging of mild steel pipe during deformation plasticity and toughness greater dangers in the tensile curve has obvious upper and lower yield point. Since the yield on the yield point elongation occurs until the end, appear deformed due to uneven surface with folds formed on the surface of the sample, called Luders band. So many stampings are often scrapped. There are two methods of its prevention. A high pre-deformation method, the pre-deformed steel stamping place after a period of time will produce Luders band, so the pre-deformed steel stamping is placed before the time not too long. Another steel, aluminum or titanium is added to the formation of a stable compound with the nitrogen to prevent the formation of air masses caused by the Coriolis deformation of aging. 

ASTM A106 Standard of Carbon Steel Pipe

ASTM A106 belongs to the American standard, which contains steel grade: Gr.A; Gr.B; Gr.C. 

ASTM A106 standard specification for seamless carbon steel pipe for high-remperature service.

Size(mm): 

Dimension Tolerances:

Pipe Type	Pipe Sizes	Tolerances
Cold Drawn	OD≤48.3mm	±0.40mm
	OD≥60.3mm	±1%mm
	WT	±12.5%

Chemical Composition:

Steel Grade	C≤	Mn	P≤	S≤	Si≥	Cr≤	Cu≤	Mo≤	Ni≤	V≤
A	0.25	0.27-0.93	0.035	0.035	0.10	0.40	0.40	0.15	0.40	0.08
B	0.30	0.29-1.06	0.035	0.035	0.10	0.40	0.40	0.15	0.40	0.08
C	0.35	0.29-1.06	0.035	0.035	0.10	0.40	0.40	0.15	0.40	0.08

Mechanical Properties:

Steel Grade	Tensile Strength(Mpa)	Yield Strength(Mpa)	Elongation(%)	Delivery Condition
A	≥330	≥205	20	Annealed
B	≥415	≥240	20	Annealed
C	≥485	≥275	20	Annealed

The Application Range of LSAW

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

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

LSAW pipe pre-welding technology

In the pipeline construction, oil and gas long-distance pipeline is toward large-diameter high-pressure transmission and the direction of the development of thick submarine pipeline, a growing number of pipeline requests using LSAW steel pipe. As China's few through-submerged arc welded pipe production line put into the introduction, to grasp the advanced welding technology LSAW is especially key.

1 Pre-welding technology status

Pre-LSAW pipe welding is the welding work part of it along the length of seam forming a "light welding," is the production of LSAW steel pipe one of the special procedures. In the early years of the LSAW is not pre-welded steel pipe production until the second generation uoe welded pipe began to emerge in the pre-welding, but this time the pre-welded to intermittent welding, spacing of about 300mm, to uoe welding control the development of third-generation unit (1968 to 1979 Q), pre-welding has been a great focus and development, the form has not changed one after another after another form of this phase of the pre-welding technology, welding technology for the pre-modern foundation. Contemporary pre-welding technology uses a succession of high-speed gas welding (mag) in the form of laser tracking and weld, welding speed up to 7 m / min, bead molding straight decency. The mag welding, the front there are two ways: one is the we and Germany and other countries using a single wire high-speed dual-supply-current gas pre-welded, the other is used in Japan's two-wire high-speed gas pre-welded. Front of those who use more gas for the pre-high-speed single-wire welding, two of China's imported from Germany LSAW weld pipe production lines are expected in this way. Quality standards from the carbon steel pipe can also be reflected in the pre-welding technology, the latest on the ocean, low, flat and acidic conditions, standard pipe and gb/t9711.3 is03183-3 of 6.3, have been clearly does not permit the use of off continued spot, indicating a pre-welded steel quality on the main form of.

2 pre-welding work

Pre-welding, steel tube for the first commissure, followed by another gas welding, seam welding conditions and welding the same time quality monitoring and feedback. Specific work process is: to accept imports of roller tube - adjust the seat tube openings - transportation equipment delivery tube leaves the tube seam - to confirm the seam quality - welding torch landed prepare - activate the laser tracker to track - shielding gas and cooling water valve open - start welding (welding speed tube to feed) _ - stop welding to the terminal extinction - lag off shielding gas - rose back to the gun position - structural steel pipe pass down procedure. This, a pre-welding cycle is complete.

Quality Requirements for Seamless Steel Pipe

1, The chemical composition
In order to improve the uniformity of chemical composition in steel and the purity of steel, to reduce the non-metallic inclusions in the tube and to improve the distribution state, it is often used to improve the chemical composition of the steel.
2, Dimensional accuracy and shape
The geometry of the seamless steel pipe mainly includes the outer diameter, wall thickness, ellipticity, length, curvature, pipe end face inclination, groove angle and the blunt edge, cross-sectional size of the steel pipe.
3, The surface quality
The standard specifies the requirements for the "smooth surface" of seamless steel tubes. Common defects include: cracks, hair lines, within the fold, outside the fold, rolling, straight, outside the straight, separated layer, scarring, pits, convex package, scratching, the spiral road, outside the spiral road, green line, correction concave, such as roller. Crack, slight internal and external straight, minor internal and external spiral, straightening, and so on. In addition to the internal and external cracks, cracks, broken, rolling, Concave, roll as a general defect.
4, Physical and chemical properties
Including mechanical properties at room temperature and mechanical properties at certain temperatures (heat and low temperature properties) and corrosion resistance (such as anti-oxidation, water erosion, acid and alkali resistance and other properties) under normal circumstances depends on the chemical composition of steel, performance and steel purity and steel heat treatment methods. In some cases, the rolling temperature and the degree of deformation of the carbon steel pipe will also affect the performance of the steel pipe.
5, Process performance, including the expansion of the pipe, flattening, curling, bending, ring pull and welding performance.
6, Microstructure, including the low-power steel pipe and high-power organization.
7, Special requirements, the user use steel pipe outside the standard request.

Production Process of Elbow Pipe Fitting

There are many kinds of processing methods for carbon steel pipe fittings. Many of them also belong to the category of mechanical processing. Most of them are stamping method, forging method, roller processing method, rolling method, bulging method, drawing method, bending method, and combination processing method . Pipe processing is the organic combination of machining and metal pressure processing.

Examples are as follows:
Forging method: the use of forging machine to pipe or part of the end to be extended, so that the outer diameter reduction, commonly used forging machine has a rotary, connecting rod, roller type.

Stamping method: Use a tapered core on the punch to extend the pipe end to the desired size and shape.

Roller method: the tube placed in the tube, the outer wheel with a roller, for the round edge processing.

Rolling method: generally do not have mandrel, suitable for thick-walled tube inside the round edge.

Bending method: there are three methods are more commonly used, one method is called extension method, the other method is called stamping method, the third is more familiar with the roller method, there are 3-4 rollers, two fixed roller, an adjustment Roller, adjust the fixed roller from the finished mild steel pipe is bent. This method is applied to a wider, if the production of spiral, the curvature can be increased.

Bulging method: one is placed in the tube rubber, the top with a punch compression, the tube protruding shape; another method is the hydraulic bulging forming, filling the middle of the tube liquid,  liquid pressure to the drum drum into the required shape , As most of our commonly used bellows production is used in this way.

High Precision Cold Drawn Steel Pipe Technology

High-precision cold drawn carbon steel pipe is a new type of high-tech energy-saving products. In recent years, the use of this technology to produce precision steel pipe has been widely used in domestic hydraulic, pneumatic cylinder, coal downhole stent (pillar), oil pump pipe, jack and other manufacturing areas. High-precision cold drawn steel pipe to promote the use of steel, improve processing efficiency, energy conservation, reduce the hydraulic cylinder, cylinder processing equipment investment is important.

Cold drawn way: the production of high-precision cold-drawn tube ─ ─ hydraulic cylinder compared with the traditional cutting process, has the following characteristics:
(1) High production efficiency: the traditional method of production of an inner diameter of 420 mm, 12 meters long cylinder to be 154 hours, with cold drawing method of production only 4 minutes.
(2) High rate of genuine: the boring of the rolling head and play a guiding role in the cutting process, the blank tube due to self-weight deflection, resulting in rolling head and boring tool deviation, resulting in waste. Genuine rate can only reach about 60%, while the use of cold-drawn method of production, genuine rate of up to 95% or more.
(3) High metal utilization: the traditional boring method of manufacturing cylinder, metal utilization rate of only 50-70%. With the drawing method of production, the metal is not only cut into iron, but can get 30% extension, metal utilization up to 95%.
(4) Improve the mechanical properties of finished mild steel pipe: the use of drawing method, so that the blank get more than 30% of the plastic deformation, due to hardening and processing of finished pipe metal strength limit greatly improved. Generally in the finished product tube strength limit increased by 60%. High-precision cold-drawn tube is a seamless hot-rolled steel pipe, DSAW steel pipe for the blank, after chemical treatment in a special cold drawn machine, through the special deformation of the design of the mold to draw to produce high-precision tube. Its dimensional accuracy of H10 ~ H8, straightness of 0.35 ~ 0.5mm / m, surface roughness of Ra1.6-0.4.

How to Distinguish the Defective Square Structural Steel Pipe？

1, Defective square structural steel pipe because the processing is not in place, the appearance will be a lot of glitches, and these burrs will be very simple scratches the pipe surface, so the first identification method came out, there are many scratches on the exterior of the Is the quality of the poor.

2, Defective side tube manufacturers in order to reach a large negative public service will increase the amount of product processing when the reduction, and this will result in products of fine and low cross-ribs, so if you find such a situation, then the best side do not buy.

3, So called square structural steel pipe is because the cross-section of the pipe is square, and poor side of the pipe in this regard is not in place will make the pipe section of the oval-shaped cross-section.

4, Residual side tube is basically not able to reach the standard specifications, so when you buy with a professional ruler about the volume can be briefly resolved.

The Fire Prevention Function of Fertilizer Special Pipe

For the practical application of fertilizer tube to overcome the lack of fire prevention, fire protection must be handled, its purpose is to improve the fire resistance of structural steel pipe to the design specification limits. Here are several different steel structure fire protection measures. 
        
First, the outsourcing level. Structure is the appearance of the fertilizer tube to add outsourcing layer, cast molding, spraying method can also be used. In-situ forming solid layer of concrete is usually outsourced to strengthen steel mesh or steel, to limit the shrinkage cracks, and to ensure that the shell strength.

Second, the water-filled (water jacket). Water-filled hollow carbon steel pipe structure is the most effective protection against fire measures. This approach can make steel in the fire to keep a lower temperature, the water circulating in the fertilizer tube, heating the heat absorbing material itself. 
         
Third, the shield. Fertilizer tube set in the refractory composition of the wall or ceiling, or within the components concealed in the gap between two walls, as long as a slight increase in refractory or not to increase the fire that is able to achieve the purpose. 
        
Fourth, the expansion material. The use of fire-resistant coating to protect steel components, this method has good fire insulation properties, construction from steel geometry restrictions, etc., generally do not need to add fertilizer tube support facilities, and the coating quality of light, there is a certain The beautiful decorative effect, belongs to modern technology and advanced fire protection measures for mild steel pipe.

Different Uses of Steel with Different Technical Conditions

Different uses of steel in accordance with the actual use and working conditions for the different response to pipe size tolerance, surface quality, chemical composition, mechanical properties, process performance, and other special properties such as, the different technical conditions.

General seamless steel pipe for conveying water, gas, oil pipelines and manufacture of fluid structural components, the response to its mechanical properties such as tensile strength, yield strength and elongation for the sample test. Duct generally work under conditions of pressure, also called pressure test done and flaring, squash, curling and other process performance tests. For large-scale long-distance crude oil, refined oil, natural gas pipelines with a pipe is to increase the carbon equivalent, welding performance, low-temperature toughness, stress corrosion under harsh conditions, corrosion, corrosion fatigue strength and corrosion environment and other requirements. Ordinary boiler tubes used in the manufacture of structural steel pipe and superheated steam boilers boiling water pipes. High-pressure boiler tubes for high pressure or high pressure superheated steam boilers, heat exchangers and pipes for high pressure equipment.

The steel thermal equipment in different conditions of high temperature and pressure of work, should ensure good surface condition, mechanical and technological properties. Generally to test its mechanical properties, flattening, and hydrostatic testing to do, high-pressure boiler tubes also asked to do the test and the grain size of more stringent non-destructive testing. Mechanical seamless steel pipe according to the application requirements to be a higher dimensional accuracy, good mechanical properties and surface condition. Regulatory requirements such as bearing high wear resistance, homogeneous, and strictly within the diameter tolerance. In addition to doing general mechanical performance test items, we need to do low-magnification, fracture, annealing (ball of the organization, mesh light, strip), non-metallic inclusions (oxides, sulfides, dot, etc.), de- indicators of carbon layer and its hardness test. Fertilizer industry often use high pressure seamless steel pressure of 2200 ~ 3200Mpa, working temperature -40 ℃ ~ 400 ℃ and the corrosive environment, transport chemical medium (such as ammonia, methanol, urea, etc.). Fertilizer industry with high-pressure seamless steel pipe should have a strong corrosion resistance, good mechanical properties and surface condition. In addition to doing mechanical properties, flattening, and hydrostatic testing, it should be based on different kinds of steel corrosion test streamlined accordingly, managers and more rigorous degree of non-destructive testing. Petroleum, geological drilling carbon steel pipe at high pressure, alternating stress, corrosive, harsh environments, it should be a high intensity level, and to wear, torsion and corrosion-resistant properties. According to the different grades of steel should be done tensile strength, yield strength, elongation, impact toughness and hardness tests. Used for oil well casing, tubing and drill pipe, is a detailed breakdown of the grade, category, and for different environmental, geological conditions selected by the user's own additional requirements for high technical requirements, to meet different specific needs. Chemical, petroleum cracking, aviation and other machinery industry with a variety of acid-resistant stainless steel pipe and mechanical properties than do the pressure test, but also specifically for the intergranular corrosion test, flattening, flaring and non-destructive testing and other tests.

Large Diameter LSAW steel pipe

The production process of the large diameter LSAW steel pipe of hot rolled coil after forming machines, coil deformation for a smooth cylindrical, straight seam welded pipe is a gas pipeline in the common pipe diameters greater than 426mm (or 508mm) the pipe is generally known as longitudinally welded pipes of large diameter.

Accoring to Welding into a tube, can be divided into DSAW steel pipe and Longitudinal two. High-frequency current skin effect and proximity effect or flux layer burning arc welding, the tube edge of the heating and melting and fusion, the final cooling effect of the extrusion pressure molding. Which the tube edge melting of high-frequency current is called ERW (ERW), using arc melting is called LSAW pipe (LSAW). Longitudinal main raw material is low carbon steel hot rolled coil, hot rolled, low pressure gas transmission, petroleum, metallurgy, construction, coal mines, ports, machinery and other industries, and oil and gas transportation, mine liquid with The conveyor roller, automotive transmission.

What is the role of carbon in carbon steel pipe performance

The role of carbon in carbon steel pipe performance:

Carbon (C): the carbon content in steel, yield point and tensile strength increased but the ductility and impact resistance to reduce carbon content of 0.23% over the deterioration of weldability, so for the welding of low alloy structural steel pipe, the carbon content is generally not more than 0.20%.

The high carbon content also reduces the steel resistant to atmospheric corrosion in the open yard of high-carbon steel is easily corroded; In addition, the carbon can increase the cold brittleness and aging sensitivity of the steel. Ordinary material seamless steel pipe for alloy steel pipe is easy to rust.

Different Uses of Steel with Different Technical Conditions

Different uses of steel in accordance with the actual use and working conditions for the different response to pipe size tolerance, surface quality, chemical composition, mechanical properties, process performance, and other special properties such as, the different technical conditions.

General seamless steel tubes for conveying water, gas, oil pipelines and manufacture of fluid structural components, the response to its mechanical properties such as tensile strength, yield strength and elongation for the sample test. Duct generally work under conditions of pressure, also called pressure test done and flaring, squash, curling and other process performance tests. For large-scale long-distance crude oil, refined oil, natural gas pipelines with a pipe is to increase the carbon equivalent, welding performance, low-temperature toughness, stress corrosion under harsh conditions, corrosion, corrosion fatigue strength and corrosion environment and other requirements. Ordinary boiler tubes used in the manufacture of structural steel pipe and superheated steam boilers boiling water pipes. High-pressure boiler tubes for high pressure or high pressure superheated steam boilers, heat exchangers and pipes for high pressure equipment.

The steel thermal equipment in different conditions of high temperature and pressure of work, should ensure good surface condition, mechanical and technological properties. Generally to test its mechanical properties, flattening, and hydrostatic testing to do, high-pressure boiler tubes also asked to do the test and the grain size of more stringent non-destructive testing. Mechanical seamless steel pipe according to the application requirements to be a higher dimensional accuracy, good mechanical properties and surface condition. Regulatory requirements such as bearing high wear resistance, homogeneous, and strictly within the diameter tolerance. In addition to doing general mechanical performance test items, we need to do low-magnification, fracture, annealing (ball of the organization, mesh light, strip), non-metallic inclusions (oxides, sulfides, dot, etc.), de- indicators of carbon layer and its hardness test. Fertilizer industry often use high pressure seamless steel pressure of 2200 ~ 3200Mpa, working temperature -40 ℃ ~ 400 ℃ and the corrosive environment, transport chemical medium (such as ammonia, methanol, urea, etc.). Fertilizer industry with high-pressure seamless carbon steel pipe should have a strong corrosion resistance, good mechanical properties and surface condition. In addition to doing mechanical properties, flattening, and hydrostatic testing, it should be based on different kinds of steel corrosion test streamlined accordingly, managers and more rigorous degree of non-destructive testing. Petroleum, geological drilling pipe at high pressure, alternating stress, corrosive, harsh environments, it should be a high intensity level, and to wear, torsion and corrosion-resistant properties. According to the different grades of steel should be done tensile strength, yield strength, elongation, impact toughness and hardness tests. Used for oil well casing, tubing and drill pipe, is a detailed breakdown of the grade, category, and for different environmental, geological conditions selected by the user's own additional requirements for high technical requirements, to meet different specific needs. Chemical, petroleum cracking, aviation and other machinery industry with a variety of acid-resistant stainless steel pipe and mechanical properties than do the pressure test, but also specifically for the intergranular corrosion test, flattening, flaring and non-destructive testing and other tests.

The Application of Seamless Steel Pipe in Various Industries

As the carbon steel pipe bending ability, so in recent years, factories, stadiums and other buildings of the roof frame, beams, columns, adopted steel housing, with the development of steel production in the construction is also more and more use ofsteel structure, daily utensils, furniture, water supply and drainage, gas, heating and ventilation, means of transport and agricultural equipment manufacturing, underground resources such as coal, oil and gas development, defense and space used guns, artillery, rockets, missiles, etc.are inseparable from steel, so the pipe on the development of national economy and people's standard of living are closely related.

Technical standards of seamless steel pipe for the full performance characteristics, correct, reasonable economic use of seamless service.In the technical standards set forth in the diameter, wall thickness and tolerances, pipe length, bending, end elliptical degree, the weight of the delivery, marking and other general provisions of the scope, lists must meet the technical requirements and mechanical properties, process performance, test items and test methods, inspection rules.For some special-purpose seamless steel tubes with special attention to some of the provisions specified in the standard requirements.So in the process of seamless steel tubes used both to understand the user's requirements, but also to meet the technical standards of mild steel pipe requirements.

What is Structural Tubing

Most people don't even notice structural tubing, but it is an integral part of everyday life for many people. This sturdy alternative to solid steel is used in an impressive array of industries and products, from shopping carts to hand rails to truck bumpers. These tubes come in many shapes and metals, all intended to serve a unique function. Without this helpful metal piping, the shape of the world's products would be much different.

Structural steel pipe is a hollow pipe commonly constructed of steel. Manufacturers purchase hot rolled metal coils from mills in order to form the various shapes needed for structural pipe. The coils are cut into the proper size and then folded into the shape needed for the tube. The next step involves welding the two sides together to make a single, strong piece of tubing. Many structural tubes are finished with a variety of chemicals to protect against natural and unnatural elements.

Structural tubing also can be made from materials other than steel. Aluminum, carbon, alloy and brass are all options that are useful for specific reasons. Aluminum and carbon provide lightweight strength, alloys often are highly resistant to the elements, and brass is popular for plumbing because of its longevity.

Circular, or tubular, is the most common shape of structural steel pipe because its rounded edges can be easily bent and handled. Tubular pipes come in a wide variety of sizes in order to work with a variety of industries. Tubes can be as small as a chopstick or large enough to double as adrainage pipe. The pipe's structure provides the strength of a solid piece of metal without the weight associated with that setup.

Structural tubing also comes in squared shapes, rectangular shapes and even oval shapes. Flat-sided square and a rectangular tubes are popular choices for building and vehicle framework. In addition to the strength each provides, the flat sides allow for holes to be drilled and bolts connected, allowing tubes to be fused together and non-tube materials, such as sheet metal, to be attached.

No matter the shape or size of the structural steel pipe, many of the tubes are chemically coated to improve performance and enhance their lifespan. Carbon, manganese, phosphorus and sulfur are all used for a variety of reasons. Usually, these chemicals are applied to help prevent oxidation and weakness caused from being exposed to nature for prolonged periods of time.

The application of seamless steel pipe in various industries

As the carbon steel pipe bending ability, so in recent years, factories, stadiums and other buildings of the roof frame, beams, columns, adopted steel housing, with the development of steel production in the construction is also more and more use ofsteel structure, daily utensils, furniture, water supply and drainage, gas, heating and ventilation, means of transport and agricultural equipment manufacturing, underground resources such as coal, oil and gas development, defense and space used guns, artillery, rockets, missiles, etc.are inseparable from steel, so the pipe on the development of national economy and people's standard of living are closely related.

Technical standards of seamless steel pipe for the full performance characteristics, correct, reasonable economic use of seamless service.In the technical standards set forth in the diameter, wall thickness and tolerances, pipe length, bending, end elliptical degree, the weight of the delivery, marking and other general provisions of the scope, lists must meet the technical requirements and mechanical properties, process performance, test items and test methods, inspection rules.For some special-purpose seamless steel tubes with special attention to some of the provisions specified in the standard requirements.So in the process of seamless steel tubes used both to understand the user's requirements, but also to meet the technical standards of carbon steel pipe requirements.

The Ways to Eliminate Rupture Phenomenon of Cold Drawn Seamless Steel Tube

High-precision cold drawn seamless carbon steel pipe abroad is generally increased in the metal alloy approach to improve material performance in the cold drawn seamless steel pipe, after all need to stress annealing, to eliminate residual stress of materials, to improve the organization of materials,improve the plastic material, thus preventing the purpose of seamless steel pipe fracture failure occurs.

At present, the common cold drawn seamless steel tube material are 45 # or 20 # steel 27SiMn steel, deformed by cold drawing of metal strength increases; However, it is at the expense of metal plasticity, toughness is the price.High-precision cold drawn seamless steel pipe is its high dimensional accuracy and high strength properties and market-based, it must ensure that the deformation within a certain range, in order to maximize the performance of materials to reduce materialadversely affected.Cold drawn seamless steel tube deformation is too small to achieve the surface finish and dimensional accuracy requirements, they can not achieve the strength index components; deformation is too large, seamless steel tubes of plastic, to reduce excessive toughness, and grain is pulled excessivelyslender, forming a fibrous tissue, the metal will have obvious anisotropy.Cold drawn seamless mild steel pipe axial, elongated parallel to the grain direction, intensity increased; cold drawn seamless steel radial, elongated perpendicular to the grain direction, but lower strength, while the biggest hydraulic cylinderStress is present in the radial seamless, so, too much distortion on the performance of fully cold drawn pipe negative.

For steel and fibrous tissue appear dislocations, vacancies and other crystal defects, generally taken to annealing or normalizing heat treatment methods to eliminate them.The purpose of annealing is grain refinement, elimination of tissue defects, reduce the hardness and improve ductility, but also easy to cold.Cold drawn seamless steel pipe production, indispensable annealing equipment, so, to develop an appropriate annealing process is to ensure that cold-drawn seamless structural steel pipe qualified organization, product defect does not appear necessary condition for fracture.If the manufacturer to unilaterally reduce production costs, reducing annealing process, is bound to adversely affect product quality.

Disadvantages of Mild Steel Pipe

Mild steel pipe cannot be hardened by heat treatment. Heat treatments only affect carbon. If there's not enough carbon in a steel, there won't be any significant improvements.

Mild steel pipe isn't as strong as carbon steel tubing. Its ductility is also a disadvantage - mild steel cannot be used in highly stressful applications such as infrastructure or construction.

If your product is for low-stress applications and designed for consumer use, you might benefit from mild steel pipe's low cost and light weight qualities. We would not recommend mild steel for high-stress applications.

Advantages of Mild Steel Pipe

Cost - Mild steel is the least expensive of all types of steel. Although it's not as strong as other steels, it's perfectly fine for moderately stressful applications such as home & garden items. Its low cost makes it extremely competitive for these low-strength everyday applications.

Ductility - Mild steel pipe is easy to bend, and doesn't break as quickly as its harder sibling, carbon steel tubing. Higher amounts of carbon cause brittleness, leading to an alloy that is more likely to snap than bend. Mild steel's ductility makes it perfect for tube bending, shaping, and welding.

Environmentally Friendly - Like other steels, mild steel can be reused and recycled many times over.

Lightweight - Carbon is heavy. Mild steel's low carbon percentage makes it easier to handle than carbon steel pipe.

Difference Between Carbon Steel Pipe and Mild Steel Pipe

Technically, carbon steel pipe and mild steel pipe aren't different types of metal at all. Mild steel is carbon steel. (Technically, all steel is "carbon steel," since carbon is the difference between iron and steel.)

Carbon steel is alloyed with up to 2% carbon. What we refer to as "mild steel" has only 0.1% - 0.3% carbon. So, when we say "carbon steel," we're most likely referring to alloys with 0.3% - 2% carbon.

"Mild steel" is more of  a slang term than anything else. Technically, it's more appropriate to reference "low carbon steel" vs. "high carbon steel." However, if you ask about mild steel pipe, your manufacturer should understand what you mean.