Description of pipe and profile using
1. Pipe and profile
is a long hollow cylinder with open ends and circular cross section.
is meaning fixed cross section in specified length.
2. Kinds of pipe and profile
2.1 Type of pipe
2.2 Type of profiles
3.1 Application of pipes
Seam welded pipes can be classified according to dimentions, quality, production procedure, test process and their application. In classification, it is common to classify steamy pipes into three classes of industrial pipes, black water pipes and excavation pipe. But this is not an exact classification and can not explain the characteristics of different pipes.
3.2 Application of profiles
1. Most of profiles are used for manufacturing of metal doors and windows. These profiles which are classified from 1 to 7 (in terms of size and characteristic) can be used in making windows and windowsframe.
2. Rectangular and square profils with small section can be used as metal fancing for door and window of houses, hard rails of steps as well as in fencing around factory walls and surrounded land and rails of sidewalks and streets.
3. Rectangle and square profils with bigger cross section which are known as cradlings have different uses in industry and construction. These profils are made in square cross section from 60*60 mm up to 270*270 mm and in rectangular cross sections from 100*40mm to 300*135 mm and are in 2.5 to 8mm thickness. They can be used in making metal columns and frameworks of buildings, also these profiles can be used in making chassis of tracks and tankers, if they have necessary physical specifications.
4. Square and square-rectangular box profiles are used in car industry.
5. Square box profiles are used in constructing legs of chair and table.
6. Profiles in Z form are mostly used in coverage of plants.
7. Angle profile and stud produce with cold rolled method. Angle profile are from 20 up to 50 mm. the use of angle profiles is in huge doors and metal frame in machines in size of 18, 12. Small Stud profiles are used in dropdown doors.
Production process of steel pipe and profile
The main operation of pipe and profile producing factories is transforming steel sheets (coils) to the final product by cold rolling, in different shapes and dimensions (open and closed profiles), this process includes following steps which are described briefly:
1. Raw materials:
Before starting of fulad mobarekeh, raw materials of most factories were supplied by European countries and Japan, but now most part of raw materials are supplied by fulad mobarake and some part is supplied by central Asia, Brazil,Europe and east Europe. the sheet should have special chemical composition and proper mechanical properties, so that cause any problem for manufactures during production and for consumers as they are used, the sheets which satisfy the ST37.2 or JIS G3731 or G3132 standards, are with chemical composition composed of (silica 0.35% , carbon 0.3% to 0.1% , sulphar 0.04% , phosphor 0.04% ,manganes 0.5% ) and are suggested for this kind of productions except for some exceptions.
2. Cutting the coils into bars
Coils are cut into bars in certain width by cutting machinery,these machinaries ,based on orders and different uses have difrent parts, some of which are full automatic and others semiautomatic. A cutting machine usually includes coil storage, carrier table, shock –absorber, coil clip, system of opening coils, system of controlling sides, smoothing sheets , guillotine and power conducting spools, power supplying rollers, the main cutting part,rollers to separate bars, bar holders and bar collectors. Coil holder has circular movement and as coil is set unit, coil holders circulates and the sheet is directed under smoothing rollers. This cause sheets to be flat and smooth. The end of sheet is cut by guillotine, so that there would be no problem in welding in other parts. Then sheets are moved by feed rollers toward to main shafts which have drivers with steel blades on them which are thermal treated and with inflexibility of (59-61) racolci and their distances are proportional to the width of required bars. The movement of sheets ( bars) is continued forward and bars are directed exactly in downstream, they are passed through to separater shafts on which small blades are fixed. Finally the first end of bars are clipped in special clip inside the barcollector. The clip then flats the diagonal of barcollector to few centimeters. In one hand, this causes closing two edges of clip and gripping the end of bars and on the other hand, at the end of discharge periode of bars, the interior layer of sheets is separated by the act of barclipper and bars can easily directed out by mobile table and the plane which is moving along the main axis. After this stage, pulling of sheet is continued by barcollector until complete length of coil is pulled . finally bars are ranked and transmitted to different units of production line.
3. Pipe and profile production:
Boxes and profiles can be produced in two methods, selecting production method depends on facilities of machine regarding it s designed. Open profiles are typically produced by direct method. Pipe and profiles producing machinary generally include bar feeder, guillotine, welding both ends of bars, a clamp, forming part (composed of two parts ,primary forming and (2) final forming), welding two edge of profile, polishing, cooler, sizing part with 4 to 6 entries – unbending and untwisting (3) automatic cut (4) dispatcher, and discharge in table. These parts can be modified based on productions and method for which machine is constructed. But it should be noted that the main operation of these units is to form the sheets passing through two upper and lower casts while circulating in different entries so that final product produced as cold .following figure shows aways of forming metal bar.
Pipe and Profile production
Production of constructional profiles and boxes can be by direct or indirect methods (producing pipe and then transforming it to the final product).each method has it s own advantages and disadvantages. In direct method bar is formed gradually passing through upper and lower casts (with driver) which designer has designed calculating power and angles of intended from distributed in each entry,and after two edge of sheet are welded with frequent welds, finally the form is completed in sizing part. Using power of casts and heat of welding, the produced profiles is not completely direct and reusing power by untwister, it s bend , cure and torsion is reformed. During the production, profiles are cut in 6m internals and packaged, and by attaching the lable and plate,the verifying quality control, they are transmitted to warehouses. By indirect method of production, at first profiles are transformed to pipes in main rolling unit with the same steps described above and with one of three methods of bending, then welding two edges, they are transformed to difrent forms by sizing and untwisting parts under upper, lower, and side pressures , or in sizing and untwisting parts the pipes are completed and final product will be pipes which are packaged after cutting. These pipe are passed through simpler units with 8 to 10 entries to change them in different form.
Advantages and disadvantages:
A. Direct method:
The profiles that produced in direct method have sharp angles,accurate dimentions , fixed weld line in upper wall and less surface curvature, and wide higher quality than other methods.because of sharp angles, different between diagonals of different parts inside the casts, and different linear speed, the wear of casts is high in this method. Also high accuracy is required regarding thermal operation and milling. The large space between indicator and profiles and ferrite decreases production speed and will be slower than indirect method and have lower efficiency. The figure shows profiles production with direct method.
B. Indirect method:
In this method the first part of machine (including forming and finishing) transforms bars to pipes by one of three ways : edge forming,central forming or forming real radius .(considering designer opinion and machine condition), are transformed to desired form in sizing parts, this way is called online method or after pipes completed and cut in these two parts, transformation is conducted in other units. In this way, as it is possible to make pipes in forming part and change at least some casts in sizing part or transmitt pipes to other welding machines, we can provide several kinds of profiles. Having variety of profiles is possible by at least one pipe producing machine. Casts are circular and production is easy with machine, also the possibility of fracture is trivial due to lack of sharp angles in thermal operation. But regarding quality, angles are more circular and the sides, weld line and surface curvature are with less accuracy than direct method. If pipes are only produced as gas or water pipes, the diagonals of pipes are considered one milimeter more than find diagonals in weld line. This value addition to diagonals is obtained by increasing linear speed. Due to the increase in diagonals of casts in each entry, sizing is decreased (0.5-0.2), and this actually extends pipes and makes them round .the pipes are tested by undestroying edicarnet test (magnetic area) before cutting or tested as offline test after cutting them.then after polishing, hydrostatic test is performed up to 70 bars pressure for 5 seconds and verifying required specific on pipes, they are packaged as hexargular packages offered to market.