UHP graphite electrode is used for the recycling of steel in the electric arc furnace industry. Its main ingredient is high-value needle coke which is made from either petroleum or coal tar. Graphite electrodes are finished with a cylinder shape and machined with threaded areas at each end. In this way, the graphite electrodes can be assembled into an electrode column using electrode nipple.
In order to meet the requirement of higher work efficiency and lower total cost, large capacity ultra-high power arc furnaces are becoming more and more popular. Because of this, UHP graphite electrodes with diameters of over 500 mm will dominate market.
Withstand large currents, high discharge rate.
Good dimension stability, not easy to deform.
Resistant to cracking & spalling.
High resistance to oxidation and thermal shock.
High mechanical strength, low electrical resistance.
High machining accuracy, good surface finishing.
Graphite electrodes are widely used for production of alloy steels, metal and other nonmetallic materials, etc.
DC electric arc furnace.
AC electric arc furnace.
Submerged arc furnace.
Ladle furnace.
Table 1: Technical Specification of UHP Graphite Electrode
| Dia. | Resistance | Density | Flexure Strength | Elastic Modulus | Ash Content | CTE | Current Load | Current Density |
| (inch) | (≤, µΩ·m) | (≥, g/cm3) | (≥, MPa) | (≤, GPa) | (≤, %) | (100 °C – 600 °C) | (A) | (A/cm2) |
| (≤, 10-6/°C) | ||||||||
| 10 | 5.5 | 1.67 | 11 | 14 | 0.3 | 1.5 | 8100–12200 | 20–30 |
| 12 | 5.5 | 1.67 | 11 | 14 | 0.3 | 1.5 | 15000–22000 | 20–30 |
| 14 | 5.5 | 1.67 | 11 | 14 | 0.3 | 1.5 | 20000–30000 | 20–30 |
| 16 | 5.5 | 1.67 | 11 | 14 | 0.3 | 1.5 | 25000–40000 | 19–30 |
| 18 | 5.5 | 1.66 | 11 | 14 | 0.3 | 1.5 | 32000–45000 | 19–27 |
| 20 | 5.5 | 1.66 | 11 | 14 | 0.3 | 1.4 | 38000–55000 | 18–27 |
| 22 | 5.5 | 1.66 | 11 | 14 | 0.3 | 1.4 | 42000–66000 | 17–26 |
| 24 | 5.5 | 1.66 | 11 | 14 | 0.3 | 1.4 | 49000–76000 | 17–26 |
Table 2: Graphite Electrode Size & Tolerance
| Diameter (mm) | Length (mm) | ||||||
| Nominal Diameter | Actual Diameter | Nominal Length | Tolerance | Short Length | |||
| (inch) | (mm) | (max.) | (min.) | (rough spot) | |||
| 10 | 250 | 256 | 251 | 248 | 1600/1800 | ±100 | -275 |
| 12 | 300 | 307 | 302 | 299 | 1600/1800 | ||
| 14 | 350 | 357 | 352 | 349 | 1600/1800 | ||
| 16 | 400 | 409 | 403 | 400 | 1600/1800/2000/2200 | ||
| 18 | 450 | 460 | 454 | 451 | 1600/1800/2000/2200 | ||
| 20 | 500 | 511 | 505 | 502 | 1800/2000/2200/2400 | ||
| 22 | 550 | 562 | 556 | 553 | 1800/2000/2200/2400 | ||
| 24 | 600 | 613 | 607 | 604 | 2000/2200/2400 | ||
There should be less than two defects or holes on the electrode surface, the maximum size of which is mentioned in the below chart.
There should be no transverse crack on the electrode surface. For the longitudinal crack, the length should be less than 5% of the electrode circumference and the width should be 0.3 to 1.0 mm.
The width of black area on electrode surface should be less than 1/10 of the electrode circumference and the length should be less than 1/3 of the electrode.
| SpecificationDefect Dimension | Nominal Diameter of Graphite Electrode (mm) | |
| 300–400 | 450–600 | |
| Diameter (mm) | 20–40 | 30–50 |
| (< 20 mm should be negligible) | (< 30 mm should be negligible) | |
| Depth (mm) | 5–10 | 10–15 |
| (< 5 mm should be negligible) | (< 10 mm should be negligible) | |