Often, seal failures are not the cause of an incorrect installation or the wrong seal type for the product being pumped, but a symptom of misalignment. If a seal starts dripping or misting product within days after installation, or suffers a “catastrophic” failure within weeks of being placed in service, the first suspect should not be the seal vendor or the technician installing the seal; misalignment should be considered as a good candidate for the cause of failure. Visualize a typical pump-motor system of bearings, shafts, seal and coupling. The weakest link in the chain is usually the mechanical seal. In the last ten years, seal technology has progressed substantially in both material composition and design (most notably cartridge seals), in compensating for shaft vibration. However, significant misalignment can still overwhelm the ability of a seal to keep both seal faces pressed firmly together or to withstand seal face cracking.
So remember, the next seal failure you encounter, quickly check misalignment with a good laser alignment system to see if the weakest link has failed due to misalignment.