Cutting an international agrochemical manufacturer’s downtime from 18 weeks to 9 weeks avoided significant lost production on a newly commissioned De Dietrich biconical dryer
Client challenge:
When a John Crane P32SP 160mm dry running seal failed shortly after the dryer was commissioned for the first time, the user faced significant production losses as they had no spare seal, no spare parts and poor response from both the seal and dryer OEMs. The lead time for either a new seal or the necessary seal spares was 18 weeks. So the user turned to NASH for help.
Our response:
Working closely with the client, we were able to quickly identify the 2 issues that had caused the seal to fail:
- Inadequate structural support had caused the dryer pedestals to rock axially and the dryer to move out of level during operation, leading to failure of the bearing
- The seal sleeve had moved axially during operation, unloading the seal and causing it to leak
Although the seal appeared to have failed catastrophically (see as received photo below), it was soon established that much of the damage to parts occurred during removal because the seal was seized on the vacuum tube due to the combined effects of the bearing failure and axial movement of the seal.
A plan was agreed involving NASH repairing and upgrading the seal in parallel with the user strengthening the dryer support structure. The target lead time was 8 weeks.
Seal repair and upgrade workscope:
- Replace both rotary and stationary seal rings
- Manufacture replacement spring plate
- Manufacture replacement composite sleeve in Hastelloy C22/316
- Manufacture replacement bearing housing
- Manufacture replacement bearing bush
- Design and manufacture a new drive arrangement (see drawing below)
- Replace all secondary seals, springs and fasteners
- Seal re-assembly
- Pressure test per API682 air test
The seal was repaired and upgraded on time in 8 weeks and the supporting structure was strengthened. The seal was successfully installed and the dryer was re-commissioned without further delay.
Client benefits:
- Projected plant downtime was reduced by 50%
- Lost production was minimised
- The client was ultimately able to meet the needs of their customers
- The ongoing reliability of the dryer was assured
NASH was able to resolve a challenging engineered mechanical seal problem when no other company could. If you find yourself in a similar situation, please feel free to contact us – we’d be delighted to help!