Electrode Inspection Checklist for Furnace Cold Repair

Cold repair is one of the few opportunities to see the electrode system as a whole. Once the furnace is down, the brick openings, seals, water-cooling jackets and connections are all exposed, and half a day of inspection at this point often prevents one unplanned stoppage during the next campaign.

Appearance and dimensions

After the electrodes are withdrawn from the furnace, do not start cleaning them at once: mark each one according to its original position and record which installation position each electrode came from. Then check each electrode for end shape, side erosion and ring marks near the melt line. Dimensional measurement should cover diameter and length at fixed points, so that the results can be compared with the previous data.

Before withdrawal, record the projection length and orientation of the electrode in the furnace; these values are used for alignment at reinstallation. If an electrode is already bowed, mark the direction of the bow so that it is not reinstalled with the load acting in the opposite direction.

• Whether the end face is flat, and whether there are pits or uneven wear.
• Depth of side erosion and its orientation.
• Diameter reduction, recorded by position.
• Surface cracks, concentrating on diameter transitions and thread roots.

Threads and connections

Failure at connections is often hidden, so they should be opened up and cleaned during inspection, checking whether the thread form is intact and whether there are signs of galling. Busbar and flexible-connection contact faces should be checked for oxidation and burning; faces that are blackened or pitted need reworking. Fasteners should be tightened to the specified torque at reinstallation and marked so that loosening can be confirmed later.

Water-cooling jackets and seals

For water-cooling jackets, focus on whether the body is deformed, whether welds show leakage traces, and whether the inlet and outlet fittings are intact. A pressure test can be run to confirm stability at the set pressure. At sealing points, check the ageing and residual thickness of the packing, and whether the bore of the electrode opening is smooth or has glass infiltration.

The residual form of the sealing packing is also informative: packing compressed into a thin, hardened sheet indicates prolonged exposure to high temperature, while local absence points to bypass flow or a gap on that side.

Brickwork and power supply circuit

The brickwork around the electrode openings is the part most easily skipped in a cold-repair inspection. Cracks in the bore wall usually start near the hot face and require lighting and a magnifier to see. If glass has penetrated the joints around the opening, clean them out and re-grout. On the power supply side, check cable insulation, busbar connections, protection settings and instrument calibration records, and confirm they match the upgraded capacity.

Spare-part quantities derived from inspection findings are more reliable than estimates based on experience. For sizes with long lead times, confirm delivery dates before the cold repair begins, so that no replacement part is missing when the work ends.

Spare parts check

1. Stock quantity and storage condition of electrodes in common sizes: protected from moisture and laid flat.
2. Reserve quantities and shelf life of sealing packing, fasteners and insulating gaskets.
3. Spares for water-cooling jackets and flexible connections, confirming that the interface type matches the installed equipment.
4. Inspection tools and record forms, so that the next inspection uses the same criteria.

The checklist itself should also be revised at each cold repair, with newly identified items added.

After the checklist has been worked through, the findings should be filed under three headings, immediate action, next cold repair and continued observation, with owners assigned. Inspection records combined with electrode service hours can serve as a basis for the spare-parts purchasing plan. For work division and interval planning, see the maintenance service approach; team and repair capability are described in About Us.