Production of Seamless Pipes Jul26

Production of Seamless Pipes...

Production of Seamless Pipes  Pipes are either seamless or welded. The manufacturing processes for seamless pipes were developed towards the end of the nineteenth century. In spite of many earlier tests, trials and technologies, the invention of the cross roll piercing process by the Mannesmann brothers towards the end of the 1880s is widely regarded as signaling the commencement of industrial scale production of seamless pipes. In the cross roll piercing process, the roll axes were arranged parallel to the stock axis but an angle to the stock plane. With the rolls rotating in the same direction, this arrangement produced a helical passage for the stock through the roll gap. Moreover the exit speed was slower by about the power of 10 than the circumferential speed of the rolls. By introducing a piercing mandrel arranged in the roll gap, solid round materials could be pierced to produce a hollow shell in the rolling heat by the action of the cross rolls. However, it was not yet possible to produce pipes of normal wall thicknesses in usable lengths by the cross piercing process alone. It was only after development and introduction of a second forming process namely ‘the pilger rolling process’ (again by Mannesmann brothers), it became possible and economically viable to produce seamless steel pipes. The pilger process also constituted an unusual and innovative technology in that the thick walled hollow shell was elongated to the finished pipe dimension by the discontinuous forging action of the pilger rolls (or dies) on a mandrel located inside the hollow shell. Presently seamless pipe is made from round billet, which is pierced through the center to make it a hollow shell and then rolled or extruded and drawn to size. The seamless pipe manufacturing process consists of...

Bearing Basics and Types of Bearings...

Bearing Basics and Types of Bearings  The term bearing is derived from the verb ‘to bear’, a bearing being a machine element that allows one part to bear (i.e., to support) another. Bearings are highly engineered, precision made components that enable machinery to move at extremely high speeds and carry remarkable loads with ease and efficiency. Generally speaking, bearings are devices that are used to enable rotational or linear movement, while reducing friction and handling stress. Bearings are considered to be the most critical components of machinery. Bearings are machine elements that constrain relative motion and reduce friction between moving parts to only the desired motion. The design of the bearings may provide for free linear movement of the moving part or for free rotational around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Many bearings also facilitate the desired motion as much as possible, such as by minimizing friction. Bearings can have many forms, but supports only two types of motions namely linear motion or rotary motion. There are two types of bearings, contact and noncontact. Contact bearings – They have mechanical contact between elements, and they include sliding, rolling, and flexural bearings. Mechanical contact means that stiffness normal to the direction of motion can be very high, but wear or fatigue can limit their life. Fig 1 shows different types of sliding and rolling bearings. Non contact bearings – They include fluid bearings and magnetic bearings. The lack of mechanical contact means that static friction can be eliminated, although viscous drag occurs when fluids are present; however, life can be virtually infinite if the external power units required to operate them do not fail. Fig 1 Different types of sliding and rolling bearings  Contact bearings Contact bearings are...

Water Management in a Steel Plant...

Water Management in a Steel Plant  Water is used in every shop of a steel plant and practically all the functions of water are utilized in the steel plant. Water is used in steel plant for process and heat transfer purposes; whereas water losses in the process are unavoidable (evaporation, drift), there is margin for further improving water use for the sake of the environment, energy efficiency, improvement of operations and for economic reasons. Use of water in a steel plant varied widely and is dependent on the availability of water, technologies employed, age and condition of the plants and equipment, kinds of the processes, and the plant operating procedures. Recycling of water also varies in a wide range in integrated steel plants.  Availability of water is one of the major factors in determining the rate of recycling. Water consumption in steel plant is mainly by evaporation, by spray from cooling towers, or by incorporation into a product. Various terms used in steel industry for water are as follows. Process water – It is the water that comes into contact with an end product or with materials incorporated into an end product. Cooling water – It is the water used exclusively for cooling purpose. Boiler feed water – It is the water introduced into boilers for conversion to steam Sanitary and service water – It is the water used for drinking, showers, general cleaning, and flushing of wastes. Intake water – It is the water which is pumped to the steel plant from water source. Make up water – It is the water added to the water system to compensate for the water losses. Recycle water – It is the water which is reused in a closed loop inside a water system often after...

Coke Oven Gas Injection in a Blast Furnace Jul19

Coke Oven Gas Injection in a Blast Furnace...

Coke Oven Gas Injection in a Blast Furnace  The iron and steel industry is one of the main consumer of energy and hence responsible for high emissions of carbon di oxide (CO2). Despite remarkable decrease in specific CO2 emissions by most of the steel plants, the total amount of CO2 emissions is growing across worldwide due to the continuous increasing of steel production which has reached to a level of 1606 million tons in 2013. Nowadays the steel industry is facing an increasing demand to minimize the energy consumption and gas emissions especially from ironmaking processes. The efficient use of byproduct gases is essentially important for the profitability of steel plant operation due to the high energy volumes and the costs involved. The injection of coke oven gas (COG) into the modern blast furnace is one of effective measures for steel industry to achieve low carbon ironmaking, energy saving and emission reduction. Coke is an essential input to the iron making process and is produced by heating coal in coke ovens. To make coke, coal is heated in the absence of oxygen to drive volatile matter from it. COG is produced as a byproduct of the process in case of byproduct coke oven batteries normally installed in steel plants. The specific amount of COG generated during coke making in the byproduct coke ovens is in the range from 290 to 340 N cum/t of coal charge depending on the volatile matters in the coal charge. The COG is currently used after its cleaning from tar, naphthalene, raw benzene, ammonia, and sulfur for heating of blast furnace stoves, ignition furnaces in sintering plant, heating furnace in rolling mills and electric power generation in power plant. The COG has a composition which consists of around 55...

Iron Ore Sinter

Iron Ore Sinter  Iron ore sinter or simply called sinter is usually the major component of a blast furnace iron bearing burden material. Sinter normally consists of various mineral phases produced by sintering of iron ore fines with fluxes, metallurgical wastes and a solid fuel. Coke breeze is normally used as fuel in the sinter mix since it supplies necessary heat energy for sintering of sinter mix. Fig 1 shows a piece of sinter. Fig 1 A piece of sinter  In sintering, a shallow bed of fine particles is agglomerated by heat exchange and partial fusion of the still mass. Heat is generated by combustion of coke breeze admixed with the bed of iron ore fines, fluxes, and metallurgical wastes (sinter mix) being agglomerated. The combustion is initiated by igniting the fuel exposed at the surface of the bed, after which a narrow, high temperature zone is caused to move through the bed by an induced draft applied at the bottom of the bed. Within this narrow zone, the surfaces of adjacent particles reach fusion temperature, and gangue constituents form a semi liquid slag. The bonding is affected by a combination of fusion, grain growth and slag liquidation. The generation of volatiles from the fuel and flux materials creates a frothy condition and the incoming air quenches and solidifies the rear edge of the advancing fusion zone. The product sinter consists of a cellular mass of sinter mix materials bonded in a slag matrix. Important factors that affect the granulation efficiency and permeability of the sinter mix are water addition, particle size distribution, ore porosity, surface properties of the iron ore and the wettability of the iron ore. During sintering process, coke breeze increases the temperature of the sinter mix within the sinter bed...