GRAPHALLOY^® Retrofit Delivers 15% More Flow and 80% Less Vibration in Overhung FCC Pumps

Pump with self lubricating GRAPHALLOY throat bushings

1. The Headache

Pushing an FCC unit for higher rates pushed its Depropanizer feed pumps well past their best-efficiency point. Shaft deflection spiked, steel wear rings rubbed, and vibration hit 1.5 in/s. Mean time between failures? Sometimes as short as two weeks.

2. The Switch

Plant engineers replaced the two case rings, throat bushing, and interstage bushings with GRAPHALLOY grade GGC—a graphite/metal alloy that won’t gall and needs no external lubrication. Clearances were cut to less than half the old metal gaps.

3. The Payoff

One real-world stress test tells the whole story: after a 30-minute dry-run during a unit upset, the pump restarted without damage.

4. Why It Worked

• Self-lubricating matrix survives dry-run, flashing, or cavitation.

• Non-galling contact lets you tighten clearances instead of opening them.

• Chemical and thermal tolerance suits hot propane/propylene mixtures.

5. Bottom Line

With tighter clearances, the refinery meets target throughput on a single pump, slashes vibration, and saves on spares and power. GRAPHALLOY turned a maintenance headache into a reliable asset—exactly what you need when every barrel counts.