Digester and Clarifier Mechanism Repair
Corroded digester and clarifier rake arms and drive components rebuilt and coated so the mechanism turns true again, without pulling the basin for new arms.
A job completed with Belzona. This describes what the Belzona system does and how it goes on, not a record of a specific project by this distributor.
The challenge
Inside a digester and a clarifier, the rake arms and drive components sit under the sludge and the gas, where corrosion works on the steel from every side. Over time the wetted metal thins across the mechanism and the arms pit and weaken. As that steel is lost, the rake runs out of true and struggles to move solids the way it was built to, and the corrosion keeps spreading until the arms can no longer carry the load. Left untreated, the mechanism fails and the basin has to come out of service for a full set of new arms, which is costly and slow.
The Belzona approach
Work starts with blasting the arms and the wetted mechanism back to clean metal so the repair has sound steel to bond to. A cold-applied composite rebuilds the pitted and thinned sections, bringing the arms back to profile so they carry the load and run true again. The whole assembly is then protected with a coating keyed to the digester environment, so the steel sits under one barrier against the sludge and the gas. The work stays cold throughout, with no hot work on the mechanism, and the rebuilt arms keep moving solids without the owner pulling the basin for new ones.
- Assess and mapThe rake arms and drive components are inspected, mapping where the wetted steel has pitted and thinned across the mechanism.
- Blast to clean metalGrit-blasting takes the arms and the wetted mechanism back to clean, profiled steel so the composite and the coating bond properly.
- Rebuild with compositeThe pitted and thinned sections are rebuilt cold with composite, restoring profile so the arms carry the load and turn true again.
- Coat for the environmentA coating keyed to the digester environment protects the rebuilt assembly, carrying the steel under one barrier against the sludge and the gas.
- Return to serviceThe rebuilt and coated mechanism is confirmed sound and handed back so the rakes keep moving solids in the basin.
The result
- Rake arms and drive components rebuilt in place without replacing the mechanism
- Pitted and thinned steel restored to profile so the rake turns true again
- Wetted assembly carried under a barrier coating keyed to the digester environment
- Basin kept in service and rebuilt by factory-trained and factory-certified Belzona applicators
In the field
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Seeing something like this?
Belzona Houston is the authorized Belzona distributor for South Texas and the Gulf, based in Alvin, Texas, we’ll survey your equipment and recommend the right cold-applied Belzona system, with 24-hour support.