Case Studies

The Problem

When a UK power station had repeated problems with mechanical seals on their Flue Gas Desulphurisation (FGD) Plant, they chose NASH to help them find a solution.

The Flexibox FF slurry seals were fitted to Plenty mixers and had the arduous duty of sealing gypsum slurry.

NASH was initially sent a set of six seals for inspection and repair. The seals were hung up solid and heavily clogged with compacted slurry. After cleaning, inspection revealed that the metal parts were heavily pitted on critical sealing surfaces due to the high chloride content of the slurry. Further detail inspection revealed that the seals had operated with a significant angular misalignment.

Excessive leakage was caused by angular misalignment combined with heavily corroded material. The leaked slurry then built up around seal parts to the point of jamming the seal solid.

 

The Solution

• NASH repaired all the FGD seals on the plant.
• The metal parts were upgraded to super duplex to significantly improve corrosion resistance.
• Minor modifications were made to the seal design to improve performance.
• The end user was advised to improve installation practice to ensure good seal alignment.

The Benefits

1. Increased seal life.
2. Reduced change outs.
3. Reduced repair costs