Sewage Tank Refurbishment

Sewage Tank Refurbishment

Background

This case study is an example of how to extend the life of your assets with the application of a Sewage tank coating repair which can be applied within minimum asset downtime, whilst reducing cost and carbon.

The specific coating repair was for a local shipyard company.

The ship was undergoing renovations to all areas and the sewage tank was identified to be in need of a repair to  prolong the life of the asset.

The Project Scope – Problem

The WGM Coatings team were engaged to survey the tank with a view to repairing the internal steel tank and extending the life due to the coating work carried out.

 

 

Method Selected

There are different methods to repair pipework refer to table below:

 

Repair Method Advantage Disadvantage
1.Replace Sewage tank New sewage tank Extensive system shutdown is required. Work is intrusive. Requirement  for manual handling/mechanical lifting. Will be expensive over a number of shutdowns.
2. Cut and weld damaged/pitted sections of tank Will remove eroded/corroded pipework System shutdown is required. Hot work is required in a confined space. Work will be expensive. The tank will carry on the corrode when returned to service if not coated.
3. Carry out repairs to damaged areas of tank with the application of Belzona products. High quality repair utilising Epoxy resin metal repair material to rebuild pitted areas of steel. Belzona Superwrap carbon fibre material with chemical resistant coating system to prevent any further corrosion.

NO Heat, Short Shutdown period &

Cost is lower versus other options.

Can be expected to last up to 15years

No disadvantages.

The method selected was to repair the internal steel and apply chemical resistant coating system. The repair will have a service life in excess of 15 years.

Product Data

Products used on HMS Shoreham were selected in consultation with the Belzona technical team and the client.

These were: Belzona 1121 for steel rebuild, Belzona Superwrap with 4 layers of carbon fibre reinforcement embedded within and 5811 immersion grade chemical resistant coating system.

Application Method

  • Grit blast internal tank areas to remove debris.
  • Loosen paint and generate a profile for coating.
  • Clean and degrease the blasted steel.
  • Rebuild steel using Belzona 1121 epoxy metal repair material.
  • Cover all rebuilt areas with 4 layers of Belzona Superwrap incorporating carbon fibre reinforcement sheet per layer.
  • Finally, a 2-coat system of Belzona 5811 is used to complete the repair.

Conclusion

This case study demonstrates the ease with which internal damage to tanks can be repaired with the tank put back into service with minimal downtime and disruption. If left, it would result in catastrophic failure of the tank.

WGM Engineering

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