A VISION TO A MISSION – My Inappreciable Contribution Can ...



INDUSTRIAL TRAINING REPORTATESSAR STEEL INDIA LTD, HAZIRA-SURAT.PRESENTED BYRaj SudaniFaculty Of Technology & Engineering (KALABHAVAN).The Maharaja Sayajirao University Of Baroda,Vadodara, Gujarat.ACKNOWLEDGEMENTIt is always a pleasure to remind the fine people in the Engineering Workshops for their sincere guidance we received to uphold our practical as well as theoretical skills in engineering.Firstly, we would like to thank Mr. Gopalji Sinha (Head-ELC) and Mr. Nirali Purohit and Ms. Shweta Yemdey and Mr. Nilesh Hirpara(Manager-EOL) for providing us with the golden opportunity for training at CRM(Cold Rolling Mill) in ESSAR STEEL INDIA LTD -Hazira.We express our deepest gratitude to Mr. Nitin Kulkarni(Head-CRM), Mr.Sushil Jamkhedkar, Mr. Anil Godhishala, Mr. Indraneel Sinha, Mr. Aditya Chaturvedi for their help and guidance and for giving prompt replies for our uncertainties regarding the plant.Finally we express our sincere regards to all other unnamed who helped us in various ways to have an interesting and fruitful training.CONTENTSEssar ProfileIntroduction to Essar SteelProcess Flow Chart at Essar Steel Hazira.Process Flow Chart at Cold Rolling MillCold Rolling Mill(CRM):Pickling ProcessAcid Regeneration Plant (ARP) Roll shopContinuous tandem cold mill (CTCM)Six high reversible mill (CRM-1)Electrolytic clean line (ECL) Batch annealed furnace (BAF)Cold skin pass mill (CSPM)Continuous galvanizing line (CGL)10.Cold Rolled Closed Annealed(CRCA)Essar ProfileHistoryThe Ruia family has been in business and in trading since the 1800s, when the family first moved to Mumbai from Rajasthan in western India. In 1956, Nand Kishore Ruia, the group founder, moved south to Chennai to begin independent business activities. In 1969 following the untimely demise of Nand Kishore Ruia, his sons Shashi and Ravi Ruia took over the group.The name of company of "ESSAR" is getting from the first letter of two brothers "Shashi" and "Ravi" S as ESS and R as AR.OverviewEssar is a multinational corporation with investments in Steel, Energy, Infrastructure and Services. With operations in more than 29 countries, it employs over 60,000 people.STEEL?Essar has a significant global presence in steel and an international portfolio of iron ore and coal mines.Essar Steel?is a fully integrated flat carbon steel manufacturer – from iron ore to ready-to-market products – with a current capacity of 14 million tonnes per annum (MTPA) and a footprint in India, Canada, USA, the Middle East and Asia. ENERGYEssar Energy is a world-class, low-cost, integrated energy company focused on India and positioned to capitalize on India's rapidly growing energy demand. The combined assets of Essar Power and Essar Oil constitute Essar Energy.Essar Oil?is a fully integrated oil and gas company of international scale with a strong presence across the hydrocarbon value chain – from exploration and production to oil retail. Currently, Essar Oil India has over 700,000 barrels per stream day (bpsd) of global crude refining capacity at Vadinar, Gujarat, India and Stanlow, UK.Essar Power?is among India's top private sector power producers with a current generation capacity of 6700MW spread across eight power plants in India and Canada.?INFRASTRUCTURE?Essar Ports?is one of India’s largest owners and operators of ports in India and provides port & terminal services for liquid, dry bulk, break bulk and general cargo. Essar Projects?is a class-leading Engineering, Procurement and Construction (EPC) contractor offering innovative execution and delivery solutions.Introduction to Essar SteelEssar Steel is a global integrated steel producer with an annual capacity of 14 million tonnes with a strong presence in intensive steel consuming markets of Asia and North America. It has operations in four countriesA 10 MTPA integrated facilities in India.A 4 MTPA steel plant in Canada.A 7 MTPA Taconite plant under execution in USA.A 0.4 MTPA downstream complex in Indonesia.Essar Steel India is an integrated steel producer with an annual production capacity of 10 million tonnes. Essar Steel’s manufacturing facility comprises ore beneficiation, pellet making, iron making, steel making, and downstream facilities including cold rolling mill, galvanising, pre-coated facility, steel processing facility, extra wide plate mill and a pipe mill. Essar Steel has set up a 1.5 MTPA plate mill and a 0.6 MTPA pipe mill at Hazira to add further value to its product portfolio. With one of India’s largest steel processing and distribution network with a capacity of 4 MTPA located at several industrial hubs.DETAILS OF VARIOUS ESSAR STEEL PLANTS IN INDIAVizag8.0 MMTPA beneficiation plant at Kirandul267 km slurry pipelinePort based 8.0 MMTPA pellet plantParadip12.0 MMTPA beneficiation plant at Dabuna253 km slurry pipelinePort based 12.0 MMTPA pellet plantHazira10 MMTPA steelmaking capacity; 3 distinct iron making units (DRI, BF & Corex)Port based plantSteel Making Technologies:4.6 MMTPA Electric Arc Furnaces (4 units)5.0 MMTPA CONARC Furnaces (2 units)Product capacities7.1 MMTPA of Hot Rolled1.4 MMTPA of Cold Rolled0.5 MMTPA of Galvanized1.5 MMTPA Plate Mill0.6 MMTPA Pipe MillPune0.6 MMTPA Cold Rolling, 0.5 MMTPA Galvanizing & 0.4 MMTPA Color Coating facilityProcess Flow Chart at Essar Steel HaziraSteel ScrapH.M From COREX & BFHBI + DRI From MIDREX Process vvvcCONARCEAFLFVD/VCD/RH DegasserCONCASTHSMLFINI casteCSPPIPE MILLCRMPLATE MILLPL Process Flow Chart at Cold Rolling Mill Complex(CRM)Hot rolled coil from HSM (Hot strip mill)Pickling line -2 Pickling line - 1HRPOSix high cold rolling mills(CRM-1)CTCM (Tandem mill)Cold rolled full hard (CRFH)Continuous galvanizing line-2Continuous galvanizing line-1GAL productElectrolytic Cleaning Line (ECL)Auto CTLRoll Forming line-2 Roll Forming line-1Batch Annealed Furnace (BAF)GAL Finishing LinePackingCold Skin Pass mill (CSPM)Corrugation LineCRCA product ICTLDMSLIR FIMIPickling ProcessPickling is the chemical removal of oxide layer (scale) from metal by immersion in acid solution The hot rolled strip or sheet has surface oxidation or iron oxide which is very brittle, hard and has coefficient of friction. The surface of the strip is objectionable when they are to be further process.Pickling is performed to remove hot rolled mill scales before any Cold rolling, Galvanizing or Painting operation.In Pickling process HCL, H2SO4,and HNO3 used as pickling solution Advantage of Hcl over H2so4:Considerably produce a uniform surface characteristics.Pickling rate is faster.It is cleaner to use and because if can be used at lower temperature due to less fumes are evolved.Cost of heating bath is less because of lower operating temperature.Easily to handle as it available in 36% concentration.Rinsing is very easy because of high solubility of chlorides Factor affecting rate of Pickling;Acid bath concentration Temp. of the acid bathTime in acid bath (line speed)Iron concentration in bathAgitation in bath Presence of inhibitorChemical composition of steelScale formation in hot rolling;In the hot rolling of carbon steel a layer of oxides forms on the surface of hot strip when the product leaves the mill typically at high temperature between 550.C and 900.C that forces oxidation and is coiled.Steel coiled at a high temperature has thicker scale is layer (750.C=12 microns whereas 570.c = 6 microns) and composition of scale is largely influenced by cooling rate after cooling the faster cooling the higher proportion of wustite The scale on steel comprises three oxide of iron that differ proportion of oxygen.Oxide layer of metal surface:Fe2o3Fe3o4feo Base metal Oxide layerPercentage of ironPercentage of oxygenFe2o3(hematite)69.938.1Fe3o4(magnetite)72.427.6Feo(wustite)77.722.3Reaction occurrence in pickling:The purpose of pickling is remove scale from the metal surface The strip of plain carbon steel passed from the hydrochloric acid and then rinse with hot water. After rinsing dryer is carried out. In this process reaction carried out which describe below:Fe2o3 + 2HCl = Fecl2 + H2OFe3o4 + 8HCl = 2Fecl3 + Fecl2 +4H2OFe2O3 + 6HCl = 2Fecl3 + 3H2OIn most of cases Fecl3 is reduced by metallic Fe and hydrogen to Fecl2Fecl3 + H = Fecl2 + HCLFecl3 + Fe = 3Fecl2Pickling line specifications:PropertiesLine-1Line-2Capacity type0.60 MTPA0.80 MTPATypePull and semi continuousContinuous shallow typeWidth850-1025 (mm)850-1550(mm)Thickness1.60-6.00(mm)1.60-5.00(mm)Coil inner diameter610mm610mmCoil outer diameter1000mm Max.2020mmLine speed170mpm150mpmPickling agentHCLHCLCoil width28 ton. Max.28 ton. Max.Defects after pickling;DefectsCorrective actionOver picklingDecrease bat concentration, reduce line speed, reduce bath temp. Under picklingDecease line speed, increase acid bath concentration Yellow patches Check rinse spray action, check pH value of the waterRoll marksCheck i/p quality, tensioned roll ScratchesCheck roll rotating, check scratches input headTelescopicity Check EPC, check dust on EPC tubeHandling DamageCheck strapping coil, proper storage of coilsAcid Regeneration plant(ARP)In acid regeneration plant mainly regeneration of hydrochloric acid from liquid product of pickling process. Liquid of pickling process mainly comprises Fecl3, Fecl2 and H2O. After process Fe particle and HCL are obtained Fe particle send for charging in blast furnace in iron making process and HCL send for pickling process. Chemical Reaction is carried as described below:2Fecl2 + 2H2O + 1/2O2 = Fe2O3 + 4HclIn this plant heating done by combustion engine. Storage tank material is FRP(fiber resistance plastic)Roll shopIn roll shop various type of process is take place such as grinding, overhauling, texturing, chocking-dechocking, lekage testing sand etc.Roll material is forge steel which harden done by induction hardening so, outer layer of roll material is martensite which is very hard and inner layer of roll material is pearlite which is soft Roll mainly used for rolling operation Roll grinder;ESSAR steel in CRM department mainly four grinder machine available which details as bellow;Specification of roll Grinder-1:Make - Herkules Franz ThomoMax. roll diameter ]= - 640mmMinimum roll diameter - 300mmRoll speed - 120RPMGrinding wheel speed - 1300RPMGrinding wheel size - 750mm Specification of roll grinder-2: Make – Herkules Franz ThomaMaximum roll diameter – 640mmMinimum roll diameter – 380mmRoll speed – 120rpmGrinding wheel speed – 1300rpmGrinding wheel size – 750mmSpecification of roll grinder – 3:Make – Arrel GuistMaximum roll diameter – 1500mmMinimum roll diameter – 480mmRoll speed – 26rpmGrinding wheel speed – 1300rpmGrinding wheel size - 915mmSpecification of roll grinder – 4:Make – Waldrich SiegenMaximum roll diameter – 1600mmMinimum roll diameter – 380mmRoll speed – 100rpmGrinding wheel speed – 1600rpmGrinding wheel size - 915mmSpecification of EDT Machine:Make – Waldrich SiegenMaximum roll diameter – 5500mmMinimum roll diameter – 380mmRoll speed – 35rpmOverhauling:Taper roller bearing – for CRM-1, CTCM & CSPM (work roll/IMR)Cylindrical roller bearing – CRM-1, & CSPM (backup roll)Margolis bearing – CTCM (Backup roll)Ball bearing – CSPM Thrust BearingLeveler Table for bearing inspectionLarge over hauling standPlunger leakage testing standPuller and tackles for different bearingChocking and Dechocking:CTCM - Work rollCRM-1 – Work rollCRM-1 – intermediate rollCSPM – Work roll Six High Rolling Mill(CRM-1) Mill specifications as given bellow:1.Pay of Reel:Material – Hot rolled and pickled low carbon steelThickness – 1.20mm to 4.50mmWidth – 700mm to 1270mmCoil inner diameter – 508mm & 610mmCoil outer diameter – 850mm & 2000mmUnwinding speed – maximum 450 m/min.Coil maximum weight – maximum 25TBack tension – 500-5000kg2. Three roll feeder:Top Roll – 280mm*1400mm driven by A.C. motorBottom Roll – 280mm*1420mm fixed free rollBending Roll – 160mm*1420mm up down by hydraulic force3. Mill Stand:Finishing product thickness – 0.15mm to 1.60mmWidth – 700mm to 1270mmRolling speed – 1200mpm Max. at 400diameter work rollSpindle Torque – 6046knm4. Roll dimension:Work roll – 400mmIntermediate roll – 490mmBackup roll – 1170mmPurpose of 6 high rolling mill is reduction of thickness, finshing, and shape correction etc. During process for coolant oil and water mix use It is cold working process so, due to strain hardening steel become harden. Reason for strain hardening is interstitial atom, lower temperature etc. In this mill one stand for passing stand so, many time passing of sheet for rolling due to frequently passing of mill production of mill is very low as compare to tandem mill But advantage of this mill is that no require any lopper system, welding system etc. and require low working space.In this mill width of sheet is not increase due to tension force which is given by DTR(delivery tension reel) and ETR(Entry tension reel) although width is increase in micron size but length of sheet is increase much more time as compare to original length. It is based on the plain stress and strain condition force applied on the roll it is done by hydraulic mechanism. Roll gap between two roll is depend on thickness sheet mainly 15% of thickness of sheet.Continues Tandem Cold Mill(CTCM) In CTCM(continues tandem cold mill) five stand and four high mill is available main advantage of tandem mill is high production as compare to six high reversible millSpecial future of tandem mill as given bellow:Flush butt welder90 degree turning point6 stands 600 mts. LopperL-2 automationMill cleaning systemAutomatic flatness controlAutomatic thickness controlDSR(Dynamic Shape Roll) in stand-5 better shape controlFlying shear to cut sheet at 200mpmSpecification of tandem mill as given bellow:Production capacity – 1.2MTPAMill speed maximum – 1000max.Entry thickness of sheet – 1.55mm to 5mmExit thickness of sheet – 0.2mm to 3mmCoil maximum weight – 28MTCoil width - 650mm (min.)&1625mm (max.)In tandem mill starting portion is flash butt welder which is used for joining of tail of one coil and head of another coil. After welding head and tail of coil fill material to each other after welding lopper portion is start. In lopper sheet turn at 90 degree. It is done by two roll which put at 45 degree mainly lopper fill 90% material at the end of coilIn lopper portion also put the bridle roll and steering unit work of bridle roll is creating tension in the sheet while steering unit control sheet at center lineAfter lopping mill portion is start. Initial thickness of sheet measured by x-ray gauge 1 and then one stand pass sheet and reduced thickness of sheet. In this mill only one time pass of mill. And then once again measure thickness of sheet. In this mill force is given to roll by using of hydraulic mechanism. The diameter of backup roll is 1350mm to 1500mm and work roll is 480mm to 560mm. Working temperature of this mill is around 50degree Celsius so, strain hardening phenomena occur and material become hard and dislocation produce. So, increase force of roll at further process. For cooling oil and water use. In stand 5 roll put bright and matt surface that depend on further process. Final measurement of thickness also put x-ray gauge after completing cold rolling.End of mill two tension reel which recoil of sheet. Mill cleaning done by hydraulic pump. After cleaning of surface strip measure the Ra value. It should be within 0.6 to 1.8 micron. If the Ra value below 0.6 than increase unit roll force for last stand while Ra value below the 1.8 reduced unit force for last standThickness(mm)Rolling ModeUnit roll force0.3-0.5Sheet thin650+/-500.5-0.8Sheet650+/-500.8-1.0Sheet700+/-501.0-1.2Sheet700+/-501.2-1.5Sheet700+/-501.5-2.0Sheet750+/-252.0-2.5Sheet800+/-25 For work roll diameter variation with crown as given bellow:StandMax. dia.(mm)Min. dia.(mm)crownRoughness(Ra)1530480140+/-100.9+/-0.12540490110+/-100.9+/-0.1355051080+/-50.6+/-0.1456052080+/-50.6+/-0.1556052080+/-50.6+/-0.1for GAL & 3+/-0.2 for CRCA For back up roll diameter variation with crown as given bellow:StandDiameter(mm)Cycle over tonnageCrownRoughness(Ra)11350-150075000T160+/-1801+/-0.221350-150075000T160+/-1801+/-0.231350-150075000T140+/-1601+/-0.241350-150075000T140+/-1601+/-0.251450-150075000T140+/-1601+/-0.2Cycle over Tenure for work roll:Stand-1Stand-2Stand-3Stand-4Stand-590KMS300KMS350KMS450KMS200KMS (plain roll)0.6-0.7 Ra on strip surface for matte roll or 200KMS ever earlier Electrolytic Cleaning Line(ECL)The purpose of this line is to remove the residual oil and iron fines present of cold rolled strip This required to avoid carbon shoots and hydrogen shoots on the strip after annealing It requirement for auto and white good product Specification of this line as given below:Thickness – 0.25 to 3 mmWidth – 600 to 1625mmLine speed – 270mpmStrip tension - 12N/nm2Oil & dirt (input) – 300mg/m2/faceIron fines – 70mg/m2/faceResidual oil on strip:Input – 250mg/m2/sideOutput – 50mg/m2/sideResidual iron fines on strip:Input – 50mg/m2/sideOutput – 25mg/m2/sideTo avoid the formation of insoluble cracking product during the annealing process The cold roll strip has following process will not be disturbedThis soiling can be rolling oils, rolling emulsions (natural synthesis, corrosion, additives etc.)Sometimes also called tramp oils (hydraulic oil other oil during cold rolling process ) can be foundFurthermore iron fines and chemical reaction product as iron scale remove This line based on the three law saponification, emulsification, deflocculating.In saponification more particle concern fatty matters such as fatty acid exist on the strip. soda or potash saponifies the ester to form soaps that will be soluble in alkaline solution. An?emulsion?is a?mixture?of two or more?liquids?that are normally?immiscible?(unmixable or unblendable). Emulsions are part of a more general class of two-phase systems of?matter called?colloids. Although the terms?colloid?and?emulsion?are sometimes used interchangeably,emulsion?should be used when both phases, dispersed and continuous, are liquids. In an emulsion, one liquid (the dispersed?phase) is?dispersed?in the other (the continuous phase). Examples of emulsions include?vinaigrettes,?milk,?mayonnaise, and some?cutting fluids for metal working. Flocculation, in the field of?chemistry, is a process wherein?colloids?come out of suspension?in the form of flake; either spontaneously or due to the addition of a?clarifying agent. The action differs from?precipitation?in that, prior to flocculation, colloids are merely suspended in a liquid and not actually dissolved in a?solution. In the flocculated system, there is no formation of a cake, since all the flocs are in the suspension.In this line alkali tank available which remove the iron fines and oil gets lessened at 85 degree Celsius and then brush scrubber remove the iron fines and then pass through ECL tank. In this tank strip become anode and cathode remove oil and then flow of water spray remove the solution of iron fine as well as oil and then passed for drying (hot air).Batch annealed furnace(BAF)It receive coil from the electrolytic cleaning line which material is very hard due to cold working process.Purpose of this line is to relive internal stress produce during cold working process and the material is subjected to only recrystalise annealing temperature In general material heated up to predetermined temp. it is known as recrystalisation temperature. And finally cool down slowly and we achieved desire property. The various property of treatment are to:Relive internal stress Improve restore ductility and toughnessEnhance machinabilityRefine grain size and orientationReduce gas content in steelImprove formability related property Start process with charging in charging of coil put in the form of stack and final shape of stack of coil is kept cone, cylinder type. When different diameter of coil is available that time higher cross section are must kept at lower portion and lower cross section area of coil must kept at upper portion. This plate separated by diffuser plate for better convection process. This coil loaded on annealing bases after charge coil placed shell which is made by stainless steel. This shape is cylinder type it also called inner cover.After clamping the inner cover ready for leak test. In this test find out leakage in the bases inner cover purge out of inert gas i.e. N2 gas which drive the O2The base ensure free of any leakage and then ready for heating sequence. In heating sequence heating bell is enter on the inner cover furnace inert atmosphere should be H2 it reduce oxidation of the steel after heating complete for cooling another bell is entered. Which is called cooling bell in this bell hot air is removed and cold air enter Heating of coil done by natural gas and air mixture. This mixture ready for combustion in 2 step high velocity burner here heating bell heat the inner cover by using of burner During process recovery, recrystalisation, grain growth is occur after annealing grain become big grain so mechanical properties are recovered.Process sequence in batch annealed furnace:Heating cold roll strip recrystallisation temp. in inert atmosphere soaking at this temp. for sufficient homogenization and necessary changesCooling at predetermine zoneHere pure H2 is used becauseVery high conductivityLow viscosityHigh reducing potentialSmaller molecular sizeHigh decarburizing powerConduction, convection and radiation occur in furnace for heat transferGrain before annealing:Cold Skin Passing Mill(CSPM)Purpose of cold skin passing mill isTo suppress the yield point phenomena, To increase roughness of the material, Shape correction of sheetCleaning of sheetIn cold skin pass mill thickness reduction of sheet occur in micron range which is negligible. Yield stress represent that deformation of material is gone elastic to plastic The reason of suppress the yield point is that coil will go for deep drawing process in automobile industries that time deep drawing not occur and wrinkle produce. Also elongation of sheet is increase. Roughness of sheet is also improve due roughness of roll is high. Here matt surface roll is used. So impression of roll put on the sheet. It is carried out because this coil will go for automobile industry which doing paint on the sheet. If roughness is low than sheet can not be old down the paint so, roughness impart is necessary.Cleaning of sheet is done because rust resistance is increase.Shape correction also take place on this mill. Shape defect produce during backward process of coil such as waviness, center braking, quarter etc.Raw material of this process is low carbon steel which emerge in batch annealing furnace. In this type mill comprises mainly 4- roll for process such as two backup roll and two work roll, anti crimping roll, wet temper unit, pay of reel, tension reel, various type of gauge.First of coil is entered in mandrel of pay of reel. Then bridle work for increase in tension then gauge measure the dimensions of sheet. Then wet temper nozzle start to flow of cooling media(oil and water). Then sheet pass from the roll air wiper flow of air to remove cooling media and then tension reel uncoil the sheet.Benefits of Wet temper unit:Prevention of iron fines on work rollGood corrosion preventing propertiesLubricant propertiesGood staining preventing properties Rust preventive unit:Type of oiler – Electrostatic high tensionNo. of coil reservoir – 3 Oil used – FUCHS 4107-STemperature reservoir – 65-75degree CelsiusTemperature spray bar – 70-80degree Celsius Benefits of electrostatic unit:Uniform coatingSignificant oil savingCoating weight flexibilityNo mechanical contactCoating material transfer efficient Here mainly low carbon material is used for this mill so in microstructure in ferrite and pearlite is available. Grain size of material is high after passing material in mill grain size become elongated in elliptical shape.Continuous Galvanizing Line(CGL)After rolling under cold roll mill then coil will go for coating in galvanizing plant. Here zinc coating take place on the coil. For galvanizing two line is available. GAL-1 and GAL-2Specification of Gal-1 line:Input material – cold rolled/hot rolled low carbon including structural steelStrip thickness – 0.30mm to 3.25mmStrip width – 800mm to 1370mmCoil inner diameter – 508/610mmCoil outer diameter – 1800mmLine speed – 180mpmSpecification of Gal-2 line:Input material – cold rolled/hot rolled low carbon including structural steelStrip thickness – 0.12mm to 0.60mmStrip width – 700mm to 1250mmCoil inner diameter – 508/610mmCoil outer diameter – 1800mmLine speed – 150mpmCoil weight – 22T(max.)Here two uncoiler for process after uncoil the coil is gone for welding. GAL line type of welding is seam welding which is high frequency resistance and it is operated by electric current. And then coil pass through bridle which create tension in the sheet. Here lopper also available in GAL-1 lopper is horizontal while in GAL-2 lopper is vertical. After lopping coil go for process section.In process section first coil heated in the furnace. Five zone in furnce is available just like Preheating zoneDirect fired furnaceRadiantive furnaceSoaking zoneJet cooling furnceIn preheating zone mainly coil heated up to 400 to 500 degree Celsius. for combustion natural gas and air is mixed. In direct fired furnce have also sub zone in zone 1, 2, 3 eight burner is available and in zone 4 64 burner is available for heating. In radiative furnace strip heated by radiation of heat. In this zone tube for heating is available which is made up of copper. In soaking zone 48 burner is available. In last zone five blower for GAL-1 and 3 GAL-2.Heated strip pass in zinc bath. Chemistry of zinc bath is Al – 0.143 to 0.030%Pb – 0.05 to 0.15%Zn – balanced zinc Working of al is control the reaction of the Zn and steel strip because this reaction between Zn and steel is high diffusion occur. Charging of bath is Zn ingot. High grade zinc, prime western zinc and al alloy. In bath three roll also available such as sink roll, seal roll and stabilizer roll. Sink roll give tension to strip for going in upward direction. Seal roll seal the zinc coating. And stabilizer roll maintain excess zinc coating. Mainly two type dross is obtained 1. Bottom dross and 2. First drossAfter coating strip go for pot cooling. In cooling done by water quench. And then coated zinc strip pass through chromic acid at high temperature. Chromic acid increase life of zinc coated strip. And then coil is again recoiled. And go for finishing line.microstructure of Zn coated material:In GAL finishing line two lines available:CorrugationCut to lengthIn corrugation line roll forming line which produce corrugated shape in strip. In figure one is represent the trapezoidal shape while in figure two is sinusoidalCRCA Finishing LineThe CRCA finishing Line is last unit of CRM plant where various type coil finished such as HRPO, CRFH, GAL, CRCA. After passing this line coil pack and go to costumer. CRCA finishing line is four which describe as bellow:DMS(Dujardin Montbard Somenor) lineLIR line.FIMI lineICTL(inspection cum trimming line) lineVarious Processes are take place:ShearingTrimmingPartingSlittingInspectionSpecification of DMS line: Make – D.M.S. FranceCapacity – 69900MT/AnnumStrip Thickness – 0.3 to 3 mmStrip width - 500 to 1300mmSlit Width – 250mm min. 5 pieces max.Yield Strength – 42kg/mm2 max. up to 3 mmSpecification of FIMI line: Make – FIMI ItalyCapacity – 140000 MT/AnnumStrip Thickness – 0.3 to 3 mmStrip Width – 400 to 1600mmShear Length – 1000mm to 3500mmYield Strength – 42N/sq.mmSpecification of LIR lineMake – D.M.S. FranceCapacity – 180000MT/AnnumStrip Thickness – 180000 MT/AnnumStrip Width - 0.4 to 2.5 mmSlit Width – 300mm min. – 3pieces max.Yield Strength – 45kg/mm2 max. up to 3mm thickSpecification of ICTL line:Make – Dong Bang KoreaCapacity – 300000MT/ANNUMStrip Width – 600 to 1650 mmStrip Thickness – 0.3 to 3mmTrim Width – 1000mm min. – 1 piecesYield Strength – 45kg/mm2 max. up to 3mm thick ................
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