Steps for Handling Galling in Electrode Threads

Galling of molybdenum electrode threads during removal and installation is usually linked to rough surfaces, foreign matter, poor lubrication or excessive tightening torque. Forcing it further easily tears the thread, so the correct approach is to judge the severity first and then choose a course of action.

Stop First to Avoid Secondary Damage

Stop applying force the moment resistance rises sharply, and do not keep turning back and forth. Record the galling position and the depth already screwed in, and look for metal chips, oxide powder or glass deposits on the threaded section. Photographing the site helps later diagnosis and discussion with the supplier.

Cleaning and Soaking

Remove foreign matter with a soft brush and clean solvent, and avoid hard tools that would score the thread. Apply a thin coat of a dedicated anti-seize compound or high-temperature lubricant, leave it for a while, then try small back-and-forth rotations. Control the temperature of any heating assistance so that local overheating does not change the material condition.

Repair and Replacement

Light tearing can be checked with a thread gauge and dressed by hand; obvious deformation or a large area of missing metal means the connector should be replaced. After repair, re-check the thread with go/no-go gauges and trial-fit it at reduced tightening torque. Keep the assembly coaxial to avoid cross-threading.

Assembly Habits That Prevent Galling

Clean the thread before assembly and check for burrs and damage from knocks; apply a suitable amount of high-temperature anti-seize compound, not too much. Turn in the first few threads by hand to confirm alignment, then tighten with a tool to the specified torque. Avoid side loads when dismantling and keep the tool aligned with the thread axis.

For connections that run hot for long periods, loosen and inspect them during maintenance rather than waiting until they seize completely. For parts that are removed and refitted repeatedly, consider replaceable connectors to reduce the difficulty of repair. Keeping a few connectors in spares shortens downtime.

After the work is done, record the galling position and cause, and focus on the same location at the next assembly.

After thread repair, carry out a trial fit to confirm smooth screwing and face contact. Only put the part back into high-temperature service once the trial fit passes, so no rework is needed during operation.

For tooling, prefer dedicated fixtures matched to the thread size to reduce clamp damage.

Standardizing tools and torque before batch dismantling costs less than dealing with the aftermath, and stops the same problem from recurring.

For electrode structure and connector design, see electrodes for electric melting furnaces.