The production process of seamless steel pipe:
Seamless steel pipe mainly complete through the tension reducing diameter. The stretchreducing process is hollow base material without mandrel continuous rolling process. Under the condition of guaranteeing the welding quality , the parent tube and pipe tension reducing diameter is the process of the whole welded pipe heated to above 950 degrees Celsius, then warp tension reducing mill (tension reducing mill, 24 times) rolled into a variety of diameter and wall thickness of the finished pipe. The hot-rolled steel pipe with this production process have essential difference to the ordinary high-frequency welded pipe, through metallographic organization and mechanical properties of the weld and the parent of the furnace heating can be achieved exactly the same. In addition, through multi pass tension reducing diameter rolling machine and automatic control make the dimensional accuracy of steel (especially the roundness and wall thickness precision pipe) is better than the same kind seamless pipe.
Our seamless pipe manufacturing process involves the following steps:
-Transformation of raw materials into steel bars (Electric arc furnace, ladle furnace, vacuumdegassing and continuous casting processes)
-Transformation of steel bars into mother pipe, which is manufactured in different types of rolling mills
Each product is manufactured in accordance with customer specifications, including heat treatment for more demanding applications. Our pipes are threaded and undergo non-destructive testing before delivery to the customer.
We also offer cold-drawing for pipes with the diameter and wall thickness required for use in boilers, superheaters, condensers, heat exchangers, automobile production and several other industrial applications.
Today, Prime Steel will discuss about the key difference between Seamless and ERW Stainless Steel Pipe
What is the Raw material required for manufacturing Seamless & ERW Stainless steel Pipes?
Seamless Steel Pipe is made from a solid round steel ‘billet’ which is heated and pushed or pulled over a form until the steel is shaped into a hollow tube.
What is the Difference Between Seamless and ERW Stainless Steel Pipes?
Electric Resistance Welding (ERW) pipe is manufactured by rolling metal and then welding it longitudinally across its length. Seamless pipe is manufactured by extruding the metal to the desired length; therefore ERW pipe have a welded joint in its cross-section, while seamless pipe does not have any joint in its cross-section through-out its length.
In Seamless pipe, there are no welding or joints and is manufactured from solid round billets. The seamless pipe is finished to dimensional and wall thickness specifications in sizes from 1/8 inch to 26 inch OD. Applicable in for High-pressure applications such as Hydrocarbon Industries & Refineries, Oil & Gas Exploration & Drilling, Oil & Gas Transportation and Air and Hydraulic cylinders, Bearings, Boilers, Automobiles etc.
ERW (Electric Resistance Welded) pipes are welded longitudinally, manufactured from Strip / Coil and can be manufactured upto 24” OD. ERW pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge. It is mainly used for low/ medium pressure applications such as transportation of water / oil.
What Technologies are used to manufacture Seamless & ERW Pipes?
Technologies for Production of Seamless & ERW Pipes “CPE” Technology” used for Seamless Pipes & Tubes Production up to 7-inches OD is the world renowned Technology. “Plug Mill” Technology used for Higher Dia. Seamless Pipes & Tubes Production from 7-inches to 14-inches,is the most reliable technology,in higher dia. Segment. High frequency Induction Welding Technology is used for ERW Pipes &Tubes upto 21-inchesOD.
How to Identify Seamless or ERW Stainless Steel pipes?
To identify that a pipe supplied is seamless or ERW, Simply read the stencil on the side of the pipe
If it is ASTM A53, Type S means seamless.
Type F is furnace but welded,
Type E is Electrical resist welded.
Thats how. It is the easiest way to identify wether pipe is seamless or ERW.
LSAW steel pipe after heat treatment is a new technology to eliminate residual stress. After the material is preheated before welding to heat treatment temperature and the butt welding process to maintain the temperature of the continuously heated member, after the welding is completed using its thermal insulation cotton allowed to cool slowly. This method can effectively reduce the welding residual stress and improve resistance to stress corrosion of metals.
Internal weld NDT since the large steel pipes in water supply project belongs, especially thethickness t = 30mm steel is used as a pipe bridge, both to withstand water pressure inside, but also the burden of its own weight and the water formed by a steel pipe moment, so the welding quality requirements are particularly high. For pipe bridge with a thickness t = 30mm large-diameter pipe, the longitudinal seam and girth weld belong to a class, require 100% of X-ray film examination and 100% ultrasonic flaw detection; and thickness t = 24mm buried pipe, longitudinal seam welding belongs to a class for 20% of the X-ray film examination and 50% of the ultrasonic flaw inspection.
Post weld heat treatment can effectively reduce the welding residual stress, and heat treatment temperature is higher, residual stress better. Large-diameter pipe post weld heat treatment can effectively improve the stress corrosion resistance of large diameter pipe, the higher the heat treatment temperature, resistance to stress corrosion increased more significant. Diffusion method metal carbide coating technology is the workpiece placed in special medium, formed by diffusion of metal carbide layer of a few microns to tens of microns on the workpiece surface. Anti-corrosion anti-corrosion of buried large diameter steel pipe and clear tubes are used to hang galvanized wire, spraying compressive strength of not less than 30N / mm2 of cement mortar lining.
Drainage pipeline refers to collection systems that discharge sewage, wastewater and stormwater drainage pipes and ancillary facilities composed. Including dry pipe, manifolds and pipes leading to the treatment plant, or any other place, whether on the streets built, as long as they play the role of drainage pipes, drainage channels should be as statistics. Length of sewer drain by all, trunks, branch pipes and inspection wells, connection length and calculate well as import and export, excluding rainwater drains mouth to the connecting pipe between the pipe and open channel into the household. When calculating a single tube should be calculated, that is, in the same street where two or more side by side drains, drainage channels and should be the length of each calculation.
Galvanized iron pipe is currently the largest amount of a material to use, because galvanized iron pipe corrosion caused by high levels of heavy metals in water, affect human health, the government sector in many countries and regions have begun to explicitly prohibit the use of galvanized iron pipes. At present, China is gradually phased out this type of pipe.
Brass is a more traditional but the price is more expensive pipe material, durable and construction more convenient. In many imported sanitary products, brass is the first choice. Price is the most important reason affecting their usage, in addition to copper corrosion is on the one hand factor.
Stainless steel tube is a more durable piping material. But its high price, and the construction process is relatively high, especially the strength of the material is hard, very difficult scene processing. Therefore, the probability of the renovation project was selected low.
Plastic composite pipe is a pipe more popular in the market because of its light weight, durable and easy construction, which can be more suitable for use in bending home improvement. Its main drawback is used for hot water pipes in use, due to thermal expansion and contraction will cause long-term dislocation wall resulting in leakage.
Difference between hot stretch reducing pipe and LSAW steel pipe are basically has the following two points:
1, Resulting in differnce on product quality due to the different processes, hot stretch reducing
also carried out a process after high-frequency welding process that lsaw steel pipe can not found ------ Longitudinal are no clear line inside and outside burrs. Burr presence will affect the tube fluid - flow, burr block the normal flow of fluid, resulting in a whirlpool. According to principles of fluid mechanics, welding must increase local compression, discontinuity make pipe safety factor is also greatly reduced, hot stretch reducing steel production process - fully taken into account the existence of the risk of burrs, to limit burr removal, making it uniform thickness, no difference in the appearance and seamless. So from this point of view, hot stretch reducing pipe joints also completed the transition seamless.
2, Weld quality directly determines the quality of welded pipe, seamless pipe is welded with the greatest difference lies. Longitudinal after the high-frequency welding, straight seam set carbon can not be eliminated, weld and the parent just join together and not completely fused into one - could not stand the test of time and pressure. Hot stretch reducing high-frequency welding steel pipe after heating to go through the whole, the overall annealing temperature of 800 degrees, and then open the change process, after which a series of processes, the weld and the parent organization performance - has been the same for the complete melting one, well done from the seam to a seamless transition.
Precision seamless steel tubes with conventional technology for the furnace + ESR -> forging or forging billet and rolling way. Product shape round bar, square flat and forgings. Then steam turbine plant for further processing, but the processing process more special shape, metal utilization after processing about 30%. To squeeze mode after production, will have the following advantages:
1, Precision seamless steel tubes in the best state of stress in the hot extrusion process, reducing the product of internal defects.
2, Easy to implement diverse cross-sectional shape, adapt more variety, small batch production.
3, In each direction of performance uniformity.
The main way to produce extrusion process: EAF + ESR -> forging or rolling cogging -> induction heating -> Extrusion -> annealing.
Extrusion and forging, rolling approach is the difference between:
1, Precision seamless extrusion heating temperatures than forging, rolling production is higher 30-60 ℃;
2, Deformation, high speed (deformed steel requires only 2-4S).
3, Multi-step, high metal consumption.
Proper way to preserve spiral pipe
1) Storage space spiral steel pipe products or warehouse, should be selected in clean, smoothdrainage area, away from harmful gases or dust in factories and mines. The presence on the ground to clear the weeds and all the debris, keeping a clean steel
2) In a warehouse not with acid, alkali, salt, cement, steel and other aggressive materials stacked together. Different varieties of steel should be stacked separately, to prevent confusion, to prevent contact corrosion
3) Large steel, rail, steel disgrace, large diameter steel pipe, forgings, etc., may open dumps
4) Small and medium steel, wire rod, rebar, medium diameter steel pipe, steel wire and wire rope, etc., can be expected in a well-ventilated storage shed, but it must be the underlying thatch
5) Some small steel, sheet, strip, silicon, or thin-walled small-diameter steel pipes, all kinds of cold-rolled, cold-drawn steel products and high prices, corrosive metal products, can be stored for storage
6) A warehouse should be based on selected geographical conditions, the general ordinary enclosed warehouse, that is the roof with walls, doors and windows tight, with the Treasury ventilation device
7) Requires the Treasury sunny attention to ventilation, rain close attention to moisture, keep the appropriate storage environment
Steel tube is used as a structural element in buildings, bridges and other structures, and in a wide variety of manufactured products. It's produced in round, square and rectangular shapes in a broad range of sizes and gauges.
Rectangular tubing has many benefits: aesthetic appeal, high strength-to-weight ratios, uniform strength, cost effectiveness and recyclability.
The advantages for designers, specifies, fabricators and end users are outlined on the
• Rectangular tubing has greater strength-to-weight ratios. So, with Rectangular tubing you need less steel, by weight, to do the job. And less weight equals less cost
• Excellent compression and support characteristics and superior resistance make Rectangular tubes particularly well suited to all types of column applications
• Rectangular steel tube is made from steel, one of the world’s most recyclable and recycled materials
• Torsional strength makes steel rectangular tube an excellent choice for bear resistant and consistent.
Rectangular tube is fire resistant and does not warp, twist, split, swell or shrink. It resists dry rot and mildew, termites and carpenter ants. For increased fire resistance, the exterior of the product may be sprayed with a fire retardant material. The interior can be filled with concrete. Tube rectangular can be readily bent, formed, punched, and drilled. New and improved methods to fasten Rectangular tubing to itself or to other materials are making its use simpler and fabrication faster.
SSAW common defects magnetic particle testing or penetration testing. Spiral pipe magnetic particle testing or penetrant testing can be effectively found that surface cracks, folding, re-skin surface defects, hairline, pinholes. For ferromagnetic materials, magnetic particle testing method should be given priority, because of its high detection sensitivity; for non-ferromagnetic material, such as stainless steel spiral pipe, is used penetrant inspection method.
Online austenitic steel spiral pipe, when the insulation is damaged or rain may have infiltrated the site, note that penetration testing to find stress corrosion cracking or pitting and other defects. However, magnetic particle or penetrant testing only on the outer surface of the pipe to detect internal defects in the surface of the powerless. The inner surface of the detector, especially crack type defect detection must be carried out by ultrasonic testing.
When the spiral pipe ends aside less resection margin, due to structural reasons detection device, spiral pipe ends head sometimes can not be effectively detected, and the end is the most likely site of the presence of cracks or other defects. If the spiral steel pipe ends there is potential for cracking tendency, weld heat affected during installation may also make potential crack. Therefore, it should be noted that after the detection of certain welded spiral steel area, to detect extended spiral steel tip defects.
Wall thickness precision steel pipe production control is a difficult process and improve the accuracy of precision steel wall thickness are mainly the following aspects:
1, heating pipes, heating should be uniform, rapid lifting ban temperature. Each heating andcooling, in order to maintain stability.
2, centering rollers, opening the same size centering rollers determine the installation is in place, embrace the central core volume adjustments related to the opening angle and various actions.
3, rolling centerline, the centerline of the car to ensure that rolling consistent with the centerline of the hole puncher avoid scrolling up and down "the tube to maintain a straight line.
4, rolling tool for head and other rolling tool wear should be promptly replaced.
5, rolling tool installation, the central leadership must ensure that the centerline of the centerline distance and rolling guide rollers perforated, which is equal to the distance from the upper and lower rollers are approximately equal.
6, perforation ram ram perforation usually selected outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm uniform thick-walled tube.
7, the mandrel mill, a mandrel to choose and the thick walled precision steel processing, the smaller size of the mandrel can be used in place of solid billet. Thickness uniformity walled tubes and solid billets, can make the probability of a significant reduction in the mandrel bending deformation, can effectively improve the precision steel tube wall thickness.
8, precision mandrel, the mandrel slenderness relatively large, generally using the first car and then hit the outside diameter of groove weld, directly open long or molding material. Mandrel outer precision control ± 0.1mm, straight mandrel deviation does not exceed 5mm. Welding, finishing insert a pin positioned between two sections of the mandrel, the total deviation to prevent the direct result of excessive welding.
9, process improvements, process improvement, prevent the intermediate precision steel pull thin wall thickness and increase exceeds the control range occurs.
(1) When the building of scaffolding outside the building facade along the line erection height is less than 15m, calculated as a single row of scaffolding; higher than 15m, calculated as a consolidated scaffolding.
(2) the upper part of the wall outside the building line chooses 1.5m or more, according to thetop of the exterior wall outside the building line or uneven length times the total height of the outer scaffolding erection calculated area; the lower part of the wall in accordance with the vertical part retracts into the envelope projected area calculate according to the appropriate height of a single row of scaffolding itself.
(3) lighting recessed portion open well: when mouth width (distance between the exterior structure) ≤3.5m, press the recessed portion exterior wall vertical projection area of a single row of scaffolding, light wells mouth with or without connecting beam are calculated together with the external walls of the integrated scaffolding; when mouth width (distance between the exterior structure) 3.5m, press the recessed portion to the inside of the vertical projection area of the external walls of integrated computing m2 scaffolding outside light wells mouth connecting beam, integrated computing and the exterior scaffolding together, without connecting beam does not count scaffolding.
(4) When the stone masonry regardless of the external walls, height of more than 1.2m, integrated computing side scaffold; when the wall thickness is greater than 40cm, integrated computing side and one side of a single row of scaffolding.
(5) large equipment base height of more than 2m, its base multiplied by height perimeter shape area (m2) to calculate a single row scaffolding.
(6) roof daughter wall surface over the roof height 1.2m, according to the inner surface of the vertical projection area to calculate single row of scaffolding.
Welded pipe is a common seen pipe which usually be used on fluid conveyance. Generally, it is defined to as the large diameter solder pipe, in accordance with the welding as a way for tube, the solder steel pipe consist spiral pipe and straight seam welding tube.
Based on the application, it can be divided into general welded pipe, galvanized welded tube, oxygen blowing metric pipe, welded tubes, wire casing, roller tube, deep well pump tubes, auto tube, transformer, electric soldering thin wall pipe, welded pipe and spiral welded tube.
Spiral welded pipe is the low carbon structural steel and low alloy structural steel strip according to certain helix Angle rolled into a tube billet, and then solder pipe joints made up, it can use a narrow strip in the production of large diameter steel tube, straight seam solder pipe is hot rolled plate after molding machine molding, roll deformation of steel coil for round cylinder, using frequent current skin effect and proximity effect or flux layer burning under the arc soldering, the tube billet is heated to melt, and fusion under certain extrusion effect, after the final cooling forming.
Welded tube is made of steel plate or steel strip after crimp forming, and then after welding. Divided into the form of the weld seam welded tube and spiral welded pipe, straight seam steel tube forming technique of common UOE forming process, JCOE steel pipe forming process.