# An Overview of Graphite Electrode Standard Grades

The most critical factor in the development of graphite electrodes is the grade of petroleum coke used, as higher grades of the petroleum coke produce higher quality electrodes. In addition to the grade of petroleum coke, several other factors can impact the quality of the graphite electrode and its ability to carry a current such as length, diameter, bulk density, resistance and porosity. For example, lower grades of coke do not allow for an electric current to pass through as easily.

There are two different types of graphite electrodes available. One type is called “SDGE,” which stands for small diameter graphite electrodes. These electrodes are most commonly used for melting scrap metal and other raw materials and are used in Electric Arc Furnaces (EAF). These electrodes carry a current that creates an arc between the electrode and the raw material, causing it to melt.

The other electrode type is the “LDGE” or large diameter graphite electrode. These types of graphite electrodes are most commonly used for steel melting in very large EAF’s requiring very high-temperature and high-intensity applications. Unlike small diameter electrodes, whose current carrying capacity ranges from 15,000 to 70,000 amps, the current capacity of LDGEs varies between 60,000 to 160,000 amps.

#### SDGE vs. LDGE

SDGEs are usually manufactured from petroleum coke, regardless of the grade. Some SDGEs are manufactured with high-grade coke, others with a lower grade coke. In fact, some SDGEs are a blend of several different grades. LDGEs on the other hand, are more commonly manufactured with premium, 100% high grade needle coke.

There are different grades specified within both electrode types, such as:

• HP – High Power
• HD – High Density
• UHP – Ultra High Power
• SHP – Super High Power

There are also other grades including regular power (RP), normal power (NP), and medium power or (MP). However, these grades are less commonly used.