Can I replace gland packing with a cartridge seal?
Often, yes. A cartridge mechanical seal can replace gland packing on many pumps, and it usually stops the constant leakage that packing needs to survive. But it only works if the stuffing box, shaft and duty suit it, so the pump has to be checked before anything is ordered.
Why people convert
- Packing has to leak a little to stay cool. A mechanical seal does not, so you stop the drip, the wet floor and the product loss.
- Packing wears the shaft or shaft sleeve over time. A mechanical seal does not run on the shaft in the same way.
- Packing needs adjusting and replacing by hand. A cartridge seal arrives as one assembled unit.
- For hazardous, hot or expensive fluids, less leakage is safer and cheaper.
What has to be checked first
- Is the shaft or sleeve in good enough condition, and is the surface finish right for a seal?
- Is there enough room in the stuffing box, and is the box bore and depth suitable?
- What is the fluid, temperature and pressure? Solids or crystals in the fluid change the seal choice.
- Is there a flush or a water supply already, and does the pump run dry at any point?
- How much shaft movement and vibration does the pump have?
Some pumps need a small modification, such as a different gland or a sleeve, to take a cartridge seal. Others cannot take one without bigger changes.
Why a cartridge, not a component seal, for a conversion
A cartridge seal is supplied assembled and set in advance, so there are no setting measurements to get wrong at the pump. On a conversion, where the fitter may never have fitted a mechanical seal before, that matters.
See a real conversion
See a real conversion: packing replaced with a cartridge seal on a Robuschi pump.
What Andrew needs from you
Pump make and model, shaft diameter, fluid, temperature, pressure, speed, and a photo of the stuffing box if you can. From that Andrew will say whether a cartridge conversion makes sense, or tell you plainly when it does not.
Related: Cartridge seals, Component seals and Gland packing guide.
Questions and answers
Will a cartridge seal fit my pump instead of packing?
Many pumps can take one, but not all. The stuffing box size, shaft condition and duty decide it, so send the pump details first.
Will it stop the leakage completely?
A mechanical seal leaks far less than packing, but no seal is a promise of zero leakage. Fitting and the duty both matter.
Do I need to change the shaft?
Only if the shaft or sleeve is worn or the wrong finish. That is checked before you buy.
Is it more expensive?
A cartridge seal costs more than a set of packing rings. The saving comes from less leakage, less shaft wear and fewer repacks over time.