Repair vs Replace Tank Mixers

Repairing vs. New  

Determining the Best Viable Option 

Believing that repairing a tank mixer during a scheduled outage is the most economical solution – you might want to consider your options! At first glance, it seems the most efficient option: remove the mixer, replace the worn parts (bearings only, seal, maybe a shaft and maybe the propeller), reinstall, and resume operations. But when the mixer is already near the end of its service life, repairing it often becomes the most expensive option — not because the repair itself is costly, but because the equipment is no longer capable of returning to a reliable state of performance.

Most mixers pulled for maintenance have been operating for ten to twenty‑five years. By this stage, unseen wear accumulates across the entire drivetrain. Bearing housings lose shape, frame interfaces distort, shafts weaken and have increased wear, and propellers develop pitting and imbalance. Even with new components installed, the mixer’s internal geometry has already drifted beyond ideal tolerance - this makes it impossible for a repair to truly reset performance back to “like new.”

Standard inspections focus on the obvious — shafts, seals, bearings and drive. But the real problems usually hide in the tolerances behind them. Housing‑to‑bearing fits, frame interfaces, and shaft runouts that can’t meet new T.I.R and accumulated structural fatigue which all contribute to vibration and premature failure. When these underlying issues remain untouched, the repaired mixer returns to service already compromised.

Another often overlooked cost of repairing legacy mixers is the poor return on repaired investment. While repairs may restore short‑term operability, the mixer is put back into service with the same outdated inefficient propeller, tank‑fluid‑lubricated bearings, limited corrosion protection, and outdated or inferior lockout systems. This results in continued spending on equipment that delivers the same performance limitations, the same maintenance burden, and the same operational risks you had 10-25 years ago—consuming capital without improving uptime, efficiency, or total cost of ownership 

Replacing an aging mixer with Milton Roy’s modern design during a planned outage delivers a stronger return on invested capital over continued repairs and ongoing maintenance. Upgraded features, including sealed radial and thrust rotating assemblies, a hermetically sealed mechanical seal, corrosion‑resistant materials (316L), optimized hydraulics, improved lockout systems, and enhanced vibration control, directly reduce energy consumption, maintenance frequency, and unplanned downtime. For mixers nearing end-of-life, ongoing repairs generate diminishing returns while total ownership costs continue to rise. A full replacement eliminates repetitive repair spending, improves operating efficiency, extends service life, and lowers long‑term risk—resulting in measurable savings and a lower total cost of ownership.