Seals
Changing a seal without stripping the machine: split and weldable seals
Quick answer
On big mills and hard-to-reach gearboxes, a conventional seal change can cost days. Split seals and on-site welded polyurethane seals cut that time.
The problem
A seal that wraps around a shaft is normally slid on from the end. That means removing the coupling, the drive and sometimes the bearing. On a large mill or deep gearbox that is days of work and lost production, and it is also where most maintenance risk sits.
Ways to avoid a full strip-down
| Method | How it works | Best for |
|---|---|---|
| Split seal | Made in two or more parts that clamp around the shaft | Mill trunnions, large gearboxes, difficult access |
| Weldable polyurethane seal | Supplied as a strip or ring that is cut and welded on site into a full ring | Very large diameters, remote sites |
| Rubber or rubber-fabric split seal | Reinforced split design with the same sealing action as a solid one | Heavy-duty shaft seals |
| Worn shaft repair sleeve | Thin sleeve fitted over a worn seal land | Shafts that are scored or worn |
| Retrofit split sealing | Fitted without moving the drive | Gearboxes, pumps, drive units |
What to check when you plan one
- Is the shaft surface good enough? A new seal will not cure a worn shaft
- Is the joint position correct, away from the main load zone?
- Does the seal material suit the oil and the temperature?
- Can the contractor weld and test the seal on site, and who will inspect the joint?
- Keep the cut-off ends and note the date and joint position for the next change
Where it pays
The more expensive the stop, the sooner a split or weldable seal pays back. On a mill, saving even one shutdown day can outweigh the whole cost of the seal. Plan the first fit carefully and the next change is quick.
Takeaway. If a seal change means stripping the drive, check whether a split or weldable version exists. The saving is mostly in downtime, not in the seal.
Put it to work in the tool