PEJVAK ANDISHE SABZ

(PASCO) INTERNATIONAL TRADING

Usage Instruction of Electrodes - Part 1

Usage Instruction of Electrodes - Part 1

Usage Instruction of Electrodes - Part 1


Content:
1. Parts of Graphite Electrode
2. Packing of Graphite Electrodes
3. Storage of Graphite Electrodes
4. Transportation of Graphite Electrodes
5. Selection of Graphite Electrodes
6. Notes in Joining and Using of Graphite Electrodes

 


1. Parts of Graphite Electrode


elec1

Sketch 1 Parts of graphite electrodes


Socket and nipple of graphite electrode are taper shape.
Nipple can be classified into two types according to thread: T3 (pitch of thread: 8.467mm) and T4 (pitch of thread: 6.350mm)
Nipple can also be classified into two types according to length: standard type (N) and extended standard type (L).

2. Packing of Graphite Electrodes
2.1 Separate packing
Electrodes and nipples are packed and delivered separately.

2.2 Preassemble
A nipple will be screwed in socket of one end of electrode. Electrode will be delivered with protective cap on both ends. Main purpose of packing is to protect electrodes and nipples against damage during storage and delivery, especially to ensure intactness of threads.

3. Storage of Graphite Electrodes
3.1 Electrodes and nipples should be put on wood, iron frame or clean cement ground to avoid clash or dirt. For electrodes that will not be used in short term, don’t remove its packing so as to avoid dusts falling on thread of nipple and socket and end surface.
3.2 Electrodes should be placed in order in warehouse with protective cushion to prevent sliding. Normally electrodes should not be piled over 2 meters high.
3.3 Electrodes should be protected against rain and moisture during storage. Damp electrodes should be dried before using to avoid crack and more oxidation during steelmaking.


elec2
Picture 1


3.4 Nipple should be kept away from high temperature during storage to prevent pitch plug from melting.

4. Transportation of Graphite Electrodes
4.1 Lifting or transporting electrodes must be operated lightly with carefulness to prevent from sliding and breakage.
4.2 To ensure thread of nipple and socket can be screwed well, do not directly lift electrode at two ends, nipple or socket of it by any hanger made by hard material. Special hoisting device should be adopted to lift and hoist unpacked electrodes.
4.3 Case of nipples should be lift and placed lightly when loading and unloading to prevent nipples from being clacked or cracked.
4.4 Protective cushion should be placed while hoisting electrode to avoid bumping damage. For users of big diameter electrodes, mechanical horizontal-vertical conversion device should be equipped.


elec3
Picture 2

5. Selection of Graphite Electrodes

5.1 To select suitable grade and diameter of electrode, furnace and transformer capacity should be considered as per below table:

Table 1 Current Carrying Capacity of Graphite Electrode

Nominal Diameter(mm)

Current CarryingCapacity
RP

HP

UHP

75

1000-1400

1000-2000  
100

1500-2400

2000-3000

 
150

3500-4900

4000-5400

 
200

5000-6900

5400-10000

 
250

7000-10000

10000-13000

 
300

10000-13000

13000-17400

18000-32000

350

13500-18000

17400-24000

22000-39000

400

18000-23500

24000-32000

28000-47000

450

22000-27000

32000-40000

34000-55000

500

25000-32000

40000-48000

41000-63000

550

28000-36000

34000-55000

48000-70000

600

35000-41000

38000-61000

55000-80000

650

    69000-89000

700

39000-48000

45000-75000

80000-100000

Table 1 applies to AC furnace. Current capacity of DC furnace, comsteel furnace or LF furnace is relatively higher.


5.2 The below factors should also be considered for electrodes selection:

  • Feeding type
  • Charging method
  • Length of the part below clamper
  • Distance between furnace wall and electrode circle
  • Ratio of fusion duration and total heating duration; Tap—Tap time
  • Type of exhaust gas system
  • Oxygen blow method and amount
  • Steel grade, period of all procedures and balance etc.


6. Notes in Joining and Using of Graphite Electrodes
6.1 Electrode joining
6.1.1 Remove the protective caps of socket and nipple. Check intactness of thread of socket. Clean sockets and nipples with compressed air.
6.1.2 Screw the lifting plug into socket of one end tightly and carefully (as shown in Picture 3), place protective cushion at the other end of electrode to avoid damage (as shown in Picture 4).

elec4
Picture 3
elec5
Picture 4


6.1.3 Blow away dust on end surface, outer surface and socket of electrodes with compressed air (as shown in Picture 5). If compressed air could not clean it thoroughly, brush should be used.

elec6
Picture 5


6.1.4 Hoist the new electrode to superposition above the electrode to be joint, and drop the new electrodes slowly directed at the socket. Put isolator between the two electrodes. When drop the electrodes, pay attention not to damage thread of socket and nipple. Then hoist the new electrode slightly, take away the isolator and blow the joining part again with compressed air.

elec7
Picture 6


6.1.5 Use torque loop to screw new electrode. Hanger and torque loop should descend synchronized until required moment is reached and end surface of two electrodes closely contact (as shown in Picture 7).

elec8
Picture 7


For recommended tightening moment, please refer to below table:

 

Table 2 Tightening moment

Diameter(mm)

75

100

150

200

250

300

650

Tightening moment(N.m)

22-28

45-55

100-125

200-260

350-450

500-600

5200

Diameter(mm)

350

400

450

500

550

600

700

Tightening moment(N.m)

1160

1360

2450

3140

3730

4220

6180



6.2 Electrodes that have been joined together should not be laid horizontally so as to avoid broken.
6.3 Correct joining of electrodes please refer to Picture 8. If any space exists between end surfaces, it must be removed after finding out the cause.
6.4 When the clamp holds the electrode, please ensure that it is below the safe line and avoid nipping the socket or nipple. (Refer to Picture 9)

elec9
Picture 8              -              Picture 9

6.5 The electrode should be used vertically and avoid sliding.
6.6 Carbon adding by electrode should be prevented, otherwise performance of electrode will be influenced
6.7 As material and produce process adopted by different manufacturers differ, the physical and chemical properties of the electrodes and nipples differ too. Do not blended use electrodes and nipples produced by different manufacturers.
6.8 When charging the furnace, in order to avoid impact brought by falling material, bulk material should be placed close to bottom of the furnace. Ensure that insulated material such as lime will not pile right beneath the electrodes, to prevent electric circuit from being influenced and electrodes broken.
6.9 Position of furnace cover should be paid attention. If the cover is not in the right position, electrode will be scratched when lifting up or down, and even broken. The socket will also be influenced if molten steel splashed on the joining part.
6.10 Sealing of furnace cover must be good to reduce air coming in. Nozzle and oxygen should be applied properly to reduce oxygen consumption brought by oxidation under high temperature.
6.11 To prevent loose and screw back

1) The phase sequence of 3-phase electrode must be anticlockwise in top view.
2) Confirm tightening torque is correct.
3) If nipple plug drops off, it must be mended before joining.
4) If new graphite electrode is used for steelmaking for the first time, in order to make the nipple plug heated and coke, please stop cooling water spray.
5) For furnace which vibrates greatly, pin could be used.

6.12 As thread can be classified into T3 and T4, pay attention to use matched lifting plug, nipple and socket.
6.13 In order to reduce consumption, please note that:

1) Make sure the duration that electrodes stay in furnace as short as possible, and keep proper negative pressure operation in melting furnace, which helps consumption reduction.
2) Avoid oxygen lance blowing directly to electrodes.
3) Properly use cooling water.

Super User

Super User

Owner of this stuff


Opening Hours

Saturday- Thursday
9.00 am - 4.00 pm

Send a message

Get in touch and see if we're a good match

© 2015 Pejvak Andishe Sabz ltd. (PASCO international trading)