Graphite electrodes nipples are used to connect two or more electrodes into column. And the purpose of that is to realize continuous use of electrodes in electric arc furnace steelmaking process. Nipples, with conventional external threads surface, are the important clamping device to extend the electrode length. Doing this avoids the unproductive consumption in smelting.
As a technical manufacturer, we know that the mismatch between the graphite electrode body and the nipple will lead to the electrode breaking during use. This not only just is an unproductive consumption in smelting, but also increases the amount of carbon in the molten steel. For these reasons, all electrode nipples are produced by our factory, not purchased.
High bulk density, precision thread accuracy.
Check the tolerance of nipples one by one.
Bending strength limits are measured.
High machining accuracy, good surface finishing.
Outstanding resistance to breakage.
Original factory production, not outsourcing.
Table 1 Technical Specification of Graphite Electrode Nipple
Item | Resistance | Density | Flexure Strength | Elastic Modulus | Ash Content | CTE |
(≤, µΩ·m) | (≥, g/cm3) | (≥, MPa) | (≤, GPa) | (≤, %) | (100 °C – 600 °C) | |
(≤, 10-6/°C) | ||||||
Regular power | 6.5 | 1.69 | 15 | 14 | 0.5 | 2.8 |
High Power | 5.5 | 1.73 | 16 | 16 | 0.3 | 2.2 |
Ultra High Power | 4.5 | 1.75 | 20 | 18 | 0.3 | 1.4 |
Table 2: Dimensions of Nipple & Sockets (TPI 3)
Electrode Dia. | Nipple Designation | Nipple | Socket | ||||
Major Dia. | Length | Pitch Dia. | Depth | Thread Length | |||
(mm) | (mm) | (mm) | (mm) | (mm) | |||
(inch) | (mm) | d1 | l1 | d4 | l2 | l3 | |
9 | 225 | 139T3N | 139.7 | 203.2 | 135.49 | 107.6 | 103.6 |
10 | 250 | 155T3N | 155.57 | 220 | 151.36 | 116 | 112 |
12 | 300 | 177T3N | 177.16 | 270.9 | 172.95 | 141.5 | 137.5 |
14/16 | 350/400 | 215T3N | 215.9 | 304.8 | 211.69 | 158.4 | 154.4 |
14/16 | 350/400 | 215T3L | 215.9 | 355.6 | 211.69 | 183.8 | 179.8 |
16/18 | 400/450 | 241T3N | 241.3 | 338.7 | 237.09 | 175.3 | 171.3 |
16/18 | 400/450 | 241T3L | 241.3 | 355.6 | 237.09 | 183.8 | 179.8 |
20 | 500 | 273T3N | 273.05 | 355.6 | 268.84 | 183.8 | 179.8 |
20 | 500 | 273T3L | 273.05 | 457.2 | 268.84 | 234.6 | 230.6 |
22 | 550 | 298T3L | 298.45 | 457.2 | 294.24 | 234.6 | 230.6 |
* Pin pitch diameter d2 is equal to socket pitch diameter d4.
* Socket minor diameter d3 is equal to pitch diameter d4 minus 3.16 mm.
* Other combinations of nominal diameter and joint are to be agreed upon between the supplier and user.
Table 3: Dimensions of Nipple & Sockets (TPI 4)
Electrode Dia. | Nipple Designation | Nipple | Socket | ||||
Major Dia. | Length | Pitch Dia. | Depth | Thread Length | |||
(mm) | (mm) | (mm) | (mm) | (mm) | |||
(inch) | (mm) | d1 | l1 | d4 | l2 | l3 | |
9 | 225 | 139T4N | 139.7 | 177.8 | 136.54 | 94.9 | 90.9 |
10 | 250 | 152T4N | 152.4 | 190.5 | 149.24 | 101.3 | 97.3 |
12 | 300 | 177T4N | 177.8 | 215.9 | 174.64 | 114 | 110 |
14 | 350 | 203T4N | 203.2 | 254 | 200.04 | 133 | 129 |
14 | 350 | 203T4L | 203.2 | 304.8 | 200.04 | 158.4 | 154.4 |
16 | 400 | 222T4N | 222.25 | 304.8 | 219.09 | 158.4 | 154.4 |
16 | 400 | 222T4L | 222.25 | 355.6 | 219.09 | 183.8 | 179.8 |
18 | 450 | 241T4N | 241.3 | 304.8 | 238.14 | 158.4 | 230.6 |
18 | 450 | 241T4L | 241.3 | 355.6 | 238.14 | 183.8 | 179.8 |
20 | 500 | 269T4N | 269.88 | 355.6 | 266.72 | 183.8 | 179.8 |
20 | 500 | 269T4L | 269.88 | 457.2 | 266.72 | 234.6 | 230.6 |
22 | 550 | 298T4N | 298.45 | 355.6 | 295.29 | 183.8 | 179.8 |
22 | 550 | 298T4L | 298.45 | 457.2 | 295.29 | 234.6 | 230.6 |
24 | 600 | 317T4N | 317.5 | 355.6 | 314.34 | 183.8 | 179.8 |
24 | 600 | 317T4L | 317.5 | 457.2 | 314.34 | 234.6 | 230.6 |
* Pin pitch diameter d2 is equal to socket pitch diameter d4.
* Socket minor diameter d3 is equal to pitch diameter d4 minus 3.16 mm.
* Other combinations of nominal diameter and joint are to be agreed upon between the supplier and user.
Table 4: Standard Electrode Sizes & Nipple Weights
Electrode | Standard Weight of Nipples | ||||||||
Nominal Electrode Size | TPI 3 | TPI 4 | |||||||
Dia. × L | T3N | T3L | T4N | T4L | |||||
inch | mm | lbs | kg | lbs | kg | lbs | kg | lbs | kg |
14 × 72 | 350 × 1800 | 32 | 14.5 | - | - | 24.3 | 11 | - | - |
16 × 72 | 400 × 1800 | 45.2 | 20.5 | 46.3 | 21 | 35.3 | 16 | 39.7 | 18 |
16 × 96 | 400 × 2400 | 45.2 | 20.5 | 46.3 | 21 | 35.3 | 16 | 39.7 | 18 |
18 × 72 | 450 × 1800 | 62.8 | 28.5 | 75 | 34 | 41.9 | 19 | 48.5 | 22 |
18 × 96 | 450 × 2400 | 62.8 | 28.5 | 75 | 34 | 41.9 | 19 | 48.5 | 22 |
20 × 72 | 500 × 1800 | 79.4 | 36 | 93.7 | 42.5 | 61.7 | 28 | 75 | 34 |
20 × 84 | 500 × 2100 | 79.4 | 36 | 93.7 | 42.5 | 61.7 | 28 | 75 | 34 |
20 × 96 | 500 × 2400 | 79.4 | 36 | 93.7 | 42.5 | 61.7 | 28 | 75 | 34 |
20 × 110 | 500 × 2700 | 79.4 | 36 | 93.7 | 42.5 | 61.7 | 28 | 75 | 34 |
22 × 84 | 550 × 2100 | - | - | - | - | 73.4 | 33.3 | 94.8 | 43 |
22 × 96 | 550 × 2400 | - | - | - | - | 73.4 | 33.3 | 94.8 | 43 |
24 × 84 | 600 × 2100 | - | - | - | - | 88.2 | 40 | 110.2 | 50 |
24 × 96 | 600 × 2400 | - | - | - | - | 88.2 | 40 | 110.2 | 50 |
24 × 110 | 600 × 2700 | - | - | - | - | 88.2 | 40 | 110.2 | 50 |
Table 5: Coupling Torque Reference for Nipple & Electrode
Electrode Diameter | inch | 8 | 9 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 |
mm | 200 | 225 | 250 | 300 | 350 | 400 | 450 | 500 | 550 | 600 | |
Easing Moment | N.m | 200–260 | 300–340 | 400–450 | 550–650 | 800–950 | 900–1100 | 1100–1400 | 1500–2000 | 1900–2500 | 2400–3000 |
Below chart is the matching relationship between electric furnace capacity, transformer power load and electrode size.
Furnace Capacity | Inner Dia. | Transformer Capacity (MVA) | Electrode Dia. | ||
t | m | RP | HP | UHP | mm |
10 | 3.35 | 5 | 7.5 | 10 | 300/350 |
15 | 3.65 | 6 | 10 | 12 | 350 |
20 | 3.95 | 7.5 | 12 | 15 | 350/400 |
25 | 4.3 | 10 | 15 | 18 | 400 |
30 | 4.6 | 12 | 18 | 22 | 400/450 |
40 | 4.9 | 15 | 22 | 27 | 450 |
50 | 5.2 | 18 | 25 | 30 | 450 |
60 | 5.5 | 20 | 27 | 35 | 500 |
70 | 6.8 | 22 | 30 | 40 | 500 |
80 | 6.1 | 25 | 35 | 45 | 500 |
100 | 6.4 | 27 | 40 | 50 | 500 |
120 | 6.7 | 30 | 45 | 60 | 550/600 |
150 | 7 | 35 | 50 | 70 | 600 |
170 | 7.3 | - | 60 | 80 | 600 |
200 | 7.6 | - | 70 | 100 | 600/700 |
250 | 8.2 | - | - | 120 | 700 |
300 | 8.8 | - | - | 150 | 700 |