Fast turnaround mechanical seal diagnosis, repair and improved operation recommendations for an Asian offset ink manufacturer experiencing frequent seal failures
Client challenge
A Malaysian offset ink manufacturer suffered regular bead mill start-up problems when the Netzsch GRD80 pressurised double mechanical seal used on the mill was compromised by viscous product that contaminated the seal (see inset) and support system. This caused significant seal damage and unplanned outages.
NASH’s advice was requested into the causes, plus the feasibility of inspecting and repairing the latest failed seal on an urgent basis.
Our response
- Based on initial photographic evidence provided by our service partner in Singapore, NASH was able to suggest a number of possible operational problems
- With this information, our client decided to fly the seal to NASH’s UK workshops via Singapore on the understanding that a rapid turnaround and return to site was assured
As a result, we: –
- Stripped the seals and sent back a detailed Inspection Report showing that heavy contamination, wear and damage had occurred to both inboard and outboard seal components
- Confirmed that the damage was due to product entering the seal cartridge across the inboard seal faces
- Suggested possible causes to be:
- Reverse pressure caused by over pressurisation of the mill chamber, allowing viscous product to enter the seal
- Product solidifying around the inboard stationary seal ring, causing it to hang up and barrier liquid to leak into the mill. Seal system pressure and level switches may have been isolated and the mill allowed to run on to finish the batch, leading to product ultimately contaminating and damaging the seal
Repairs: –
- The seal was repaired and returned to site cost-effectively
- As requested, turnaround time was as short as possible
Recommendations: –
The NASH team also advised that to prevent any recurrence of the problem: –
- The seal support system and associated pipe work should be comprehensively cleaned and checked for blockages
- All pressure switches and gauges should be checked and calibrated
- The seal and seal support system should be fully vented of air prior to start up
- To eliminate the possibility of reverse pressure or seal hang up, the mill should be cleaned immediately after every batch to avoid product setting in the mill chamber
Benefits
- The repaired seal was returned to Malaysia very swiftly
- The operator could look forward to improved mechanical seal performance
- High quality technical support ensured further disruption to ink production was minimised