The RP200 graphite electrode with 122T4 nipples is a regular power grade electrode built for foundries, rolling mills and mid-sized melt shops that need dependable performance without the cost of premium grades. It is engineered around the duty it actually sees: lower current density, moderate thermal cycling and a predictable replacement interval.
What the RP200 Designation Means
RP stands for regular power, the grade family intended for lower current density duty. RP200 identifies a regular power electrode in the 200 mm nominal diameter class supplied in this product family. The 122T4 element defines the nipple: a T4 tapered-thread connector matched to the machined socket of the electrode. Nipple threads for furnace electrodes follow the T-series designation practice described in IEC 60239, and the socket and nipple are machined as a matched pair so that the joint presents full contact over the thread flank.
Typical Properties
| Property | Typical value for this grade | Test method reference |
|---|---|---|
| Electrical resistivity | About 8-9 micro-ohm-m | ASTM C611 |
| Bulk density | About 1.52-1.58 g/cm3 | ASTM C559 |
| Flexural strength | Above 8 MPa | ASTM C651 |
| Sulfur in the coke feedstock | Below 0.5 percent | ASTM D4239 |
| Ash | Up to about 0.5 percent | Mill certificate data |
| Typical current density | Up to about 20 A/cm2 | Design basis |
Values are typical for the grade and are confirmed per heat number on the mill test certificate. Medium purity petroleum coke is used, which keeps cost down while holding conductivity within the regular power band.
Applications and Duty Match
RP grade electrodes are used in mid-sized electric arc furnaces working with moderate scrap charges, in ladle refining where stable arc behaviour matters more than peak power, and in foundry melting of non-ferrous metals and specialty irons. In these duties the electrode is usually replaced on condition rather than on a fixed schedule, and a service life in the range of several tens of heats per electrode is typical of well-run operations. Where the transformer has been uprated or where heavy oxygen lancing is used, the plant should move to a higher grade rather than raise the duty on an RP column.
Frequently Asked Questions
Q: What does RP200 with 122T4 nipples cover?
A: A regular power grade electrode in the 200 mm diameter class, supplied with matched T4 tapered-thread nipples of the 122T4 size for jointing into a furnace column.
Q: Which furnaces suit this grade best?
A: Mid-sized electric arc furnaces, ladle refining stations and foundry melting units operating at current densities up to about 20 A/cm2 with moderate thermal cycling.
Q: How is the joint made reliable?
A: By using a matched electrode and nipple set, keeping both thread surfaces clean, and applying the specified torque with a calibrated wrench. Arcing at the joint is almost always a torque or cleanliness problem.
Q: What should be checked on delivery?
A: Diameter and length against the purchase drawing, socket condition, nipple dimensions, packing and support rings, and the mill test certificate for the heat number.
Q: When should a plant move to HP or UHP grade?
A: When current density rises above the regular power band, when tap-to-tap times are shortened, or when oxygen lancing increases side oxidation beyond what this grade tolerates.