A NASH inspection found incorrect face material in a dry running seal caused rapid face wear and poor seal performance. Upgrading the rotary seal rings to a grade of carbon more suitable for operation in dry nitrogen solved the problem
An Eire pharmaceutical manufacturer needed help to improve the performance of Flowserve Mixerpac 2552 pressurised double dry running mechanical seals fitted to a pair of Comber filter dryers.
Average seal life was only 10 months, causing numerous unplanned outages and additional expensive seal changes. Seal repairs via the OEM were slow, costly and did not improve seal performance.
Our filter dryer service partner in Eire removed a failed seal from one dryer and we shipped it to our UK factory.
The NASH team stripped the seal and prepared a detailed Inspection Report, which showed that both inboard and outboard rotary seal rings had suffered full nose face wear.
The face wear produced a significant amount of wear debris that ultimately caused the outboard rotary seal ring to hang up (see above).
This explained the sudden leakage of nitrogen barrier gas to atmosphere via the outboard leakage port and the high flow of nitrogen witnessed by the operator via the flow gauge on the gas panel.
Our specific findings concluded
- That the cause of high face wear was inappropriate carbon material used by the seal OEM which was not suitable for operation in dry nitrogen
- Significant wear debris had also built up in the inboard sanitary gland and was in danger of entering the dryer
- There was additional evidence of product crystallisation on the inboard rotary sliding diameter – another potential cause of hang up and seal failure
Repair & Upgrade
- Carbon faces were upgraded to NASH C300 carbon, an FDA approved grade suitable for operation in dry nitrogen
- All other seal components were either repaired or replaced to original specification, including those components in FDA approved materials
- The seal was assembled, inspected and pressure tested prior to dispatch
The NASH team advised that the end-user should
- Investigate and eliminate the cause of product crystallisation on the inboard side of the seal
- Ensure the inboard seal sanitary gland was cleaned regularly to avoid the possibly of product contamination
- The seal was repaired and upgraded in 4 weeks, compared to 8 weeks for repair via the OEM
- Upgraded carbon faces eliminated face wear, premature seal failure and unplanned dryer outages
- Mean time between seal change-outs is now 3 years.
- Costly dryer down time and seal repairs were also eliminated
- The possibility of process contamination was minimised
NASH has repaired and upgraded other sizes of Flowserve Mixerpac 2552 dry running cartridges, including 130 mm, 145 mm, 150 mm, 175 mm and 180 mm.
If you operate or service filter dryers and want to improve mechanical seal and dryer performance, please feel free to contact us – we’re here to help.