Case Studies

The Problem

An international coatings manufacturer was experiencing poor seal reliability on a Netzsch Mastermix Tiger Mill.

The double mechanical seal unit had failed 3 times in 3 months, having previously performed reliably.

The failures were proving costly in terms of both lost production and repair costs. Furthermore, the root cause of the problem had not been identified.

The Solution

Working with the equipment manufacturer, a failed seal unit was sent to NASH for strip down and assessment.

The seal was heavily contaminated with product. Both inboard and outboard faces were heavily scored, blistered and chipped.

The overall length of 2 of the faces was also undersize and several other key component dimensions were not within tolerance.

A visit to site to inspect the mill and gather service history confirmed that:

• The seals had been repaired by an unapproved third party repairer
• The seal support system pressure switch was not working
• The mill was operated after the seal had failed

The seal was repaired with all new faces, elastomers, springs and main sleeve and returned to site having undergone a successful pressure test. The equipment manufacturer refitted the seal after cleaning out the seal support system and fitting a replacement pressure switch. The mill was successfully re-commissioned.

 

The Benefits

By working with NASH and the original equipment manufacturer, the reasons for poor seal performance were quickly identified and addressed. The performance of the mill was restored, avoiding further costly production delays and maintenance bills.