COIDAN

1 COIDANCOIDANGRAPHITE PRODUCTS LTDGRAPHITE VACUUM FURNACE graphite engineers GRAPHITE ELECTRODESGRAPHITE VACUUM FURNACE CONTENTS Introduction Manufacturing Technical DataTolerances & Packaging Types of ElectrodesStorage & Handling InstallationRe-machining Trouble ShootingCustomer Data SheetGRAPHITE VACUUM FURNACE graphite engineersiphone GRAPHITE ELECTRODESI ntroductionGraphite is produced artificially by using carbon and selected binding materials such as pitch or tar. The specific characteristics of graphite are:Low electrical resistivity Good lubrication properties High thermal conductivity High thermal shock resistance Chemically stable Graphite ManufactureThe basic production steps in the manufacture of graphite electrodes comprise the following:Forming Baking Impregnation Graphitising Machining FormingThe coke is crushed into specific particle sizes, depending on the final diameter and the individual application of the electrode .

2 To bind the coke particles, controlled amounts of pitch are added. The resulting plastic mix is extruded through a forming press and cut into specified lengths, making the green electrodes .BakingThe baking process is carried out at temperatures of 800 C - 1200 C. The pitch is carbonizing at this point and about 40% of the pitch evaporates. ImpregnationBulk density and other physical properties can be improved by further pitch impregnation. All COIDAN electrodes are impregnated in this way. This is why the regular power grade achieves minimum bulk density of 1,62 graphitising process takes place at approximately 2800 C - 3200 C. The amorphous carbon is transformed into graphite.

3 MachiningFinally the electrodes are machined to specified dimensions according to IEC 60239:2005 standard. GRAPHITE ELECTRODEST echnical Data *DESCRIPTIONUNITHIGH POWER TYPE HPHIGH POWER TYPE HPSUPER HIGH POWER TYPE SHPULTRA HIGH POWER TYPE UHPULTRA HIGH POWER TYPE UHPD iameter of Electrodemm200-300350-500250-450250-3003 50-600Sp. El. Resistivity max. Strength of * These technical data are actual data acc. to manufacturers CERTIFICATES OF QUALITY. These values are typical and may vary 5%.Current Carrying Capacities / AmpereNOMINAL DIAMETERHP-ELECTRODESHP-ELECTRODEUHP-ELE CTRODE inchmmelectric arc furnace furnace arc furnace furnace arc furnace furnace GRAPHITE ELECTRODESD imensions of Truncated Cone Nipples (4 TPI)

4 *DIAMETERNIPPLESOCKET inchmmTypDia T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 T4 * Nipples are provided with pitch Sizes and TolerancesDIAMETER/MMLENGTH/MMNominal DiameterActual DiameterNominal UHP820020420117001700+100/ -759225230225170017001025025625217001700 1230030730318001800143503573531800180016 40040840418001800/2000184504594551800180 0/2400+/-1002050051150518001800-24002255 05625561800-2400246006136071800-2400 GRAPHITE ELECTRODEST ypes of ElectrodesThe correct type of electrode for varying operating conditions is mainly influenced by the maximum current carrying capacity. The following table shows the different electrode types and their matching current carrying capacities and will provide a rough idea for selection of COIDAN HP:High power grade is for foundry operations (electric arc furnace: EAF) and for ladle furnaces (LF) and occasionally for electric arc furnace operations, if the furnace parameters are UHP.

5 Ultra high power grade is suitable for electric arc furnace operations and ladle furnace operations with heavy current current load for EAFE lectrode diameter / mmCurrent load / kACurrent load / kAHPUHP200250300350400450500550010203040 506070 Maximum current load for LFElectrode diameter / mm GRAPHITE ELECTRODESS torage and handlingCoidan electrodes are produced with tight tolerances to ensure the satisfaction of our customers. To run your furnace without problems you have to take care not to damage any parts of the electrodes. Therefore it is essential to keep the electrodes in their wooden cases until you are ready to use them on the furnace. Damage to end faces and to the threads of the socket can cause which are not equipped with preset nipples - first require a nipple inserting.

6 It is essential to ensure the socket and nipple are clean before the lifting eye into the empty socket of the electrode and ensure that the socket threads are not the opposite end of the electrode and nipple when assembling the two electrodes - clean the socket of the lower electrode with compressed a spacer between the electrodes to prevent damage to the socket and the nipple when lowering the new electrode by crane. Remove the spacer and tighten the ensure efficient operation we recommend the following tightening torques. Excessive torque damages the electrode , insufficient torque causes loose joints and hot tightening torquesELECTRODE DIAMETER / MMTORQUE / NM20025022535025045030065035085040010504 501400500190055025006003000 Re-machiningIf you have broken electrodes please feel free to contact us.

7 We will be pleased to supply you with information regarding re-machining and recovery of scrap electrodes. GRAPHITE ELECTRODESYESNOYESNOYESNOYESNONONONONONO NONONONOYESYESYESYESNOTop joints breaksBottom jointsYESYESNOYESYESNOYESYESNOYESYESYESN ONOYESYESYESNOIs the nipple preset in line with the equator?Is the scrap evenly distributed?Are the columns always centered in roof ports?Are you clamping on joints?Is the tilting jerky?Is there any non conductor in the scrap?Is heavy scrap correctly loadedIs the torque correct?Is the proper jointing procedure followed?Do you use the correct nipple?Is the current regulation correct?Has the power programme been increased?

8 ContactCorrect nipple positionCorrect loading practiceCorrect roof/arms centeringCorrect practiceCorrect tilting mechanismImprove scrap preparationCorrect scrap loadingAdjust torqueCorrect faultCorrect practiceReset regulationUse higher grade electrodesCorrect loading practiceCorrect practiceCorrect practiceAdjust torqueCorrect faultCorrect practiceReset regulationUse higher grade electrodesCOIDANCOIDANGRAPHITE PRODUCTS LTDCOIDANCOIDANGRAPHITE PRODUCTS LTDIs the scrap evenly distributed?Have you been dipping?Is oxygen practice modified?Is the torque correct?Is the proper jointing procedure followed?Do you use the correct nipple?Is the current regulation correct?

9 Has the power programme been increased? ContactTrouble ShootingYou should firstly distinguish between a joint- or body-breakage, unscrewing of the electrode or increased consumption rate. The following charts may help you to solve your problem. GRAPHITE ELECTRODESYESYESYESYESYESNONONONONONONON ONOYESYESYESYESYESYESYESYESBody breaksUnscrewingIncreased electrode consumptionNONONONOYESNOYESYESNOYESYESNO NOIs the scrap evenly distributed?Are the columns always centered in roof ports?Is the tilting jerky?Is the current regulation correct?Has the power programme been increased?ContactCorrect loading practiceCorrect roof/arms centeringCorrect tilting mechanismReset regulationUse higher grade electrodesChange phase sequenceAdjust torqueCorrect faultCorrect practiceReset regulationUse higher grade electrodesReset systemCorrect jointing procedure/torqueCorrect practiceYou may have undetected stubsCheck oxygen practice and correct if modifiedCOIDANCOIDANGRAPHITE PRODUCTS LTDCOIDANCOIDANGRAPHITE PRODUCTS LTDCOIDANCOIDANGRAPHITE PRODUCTS LTDNOYESNOIs the phase sequence anti clockwise?

10 Is the torque correct?Is the proper jointing procedure followed?Do you use the correct nipple?Is the current regulation correct?Has the power programme been increased?ContactHas the production rate decreased?Has the energy consumption increased?Has the power programme been changed?Has the fume exhaust been altered?Are joint areas overheating?Have the arc tips been dipped?Are the arc tips irregular?Are the columns more tapered?Contact COIDANCOIDANGRAPHITE PRODUCTS LTDC ontactCOIDANCOIDANGRAPHITE PRODUCTS LTDC ontactCOIDANCOIDANGRAPHITE PRODUCTS LTDC ontact GRAPHITE ELECTRODESP lease return the completed furnace data DATA SHEETC ustomer: .. Address: ..Telephone.