Restoring a Severely Corroded Air Line at a Power Plant with Belzona
The Challenge
At a renowned refinery in India, a section of the plant air line had suffered extensive environmental corrosion following prolonged exposure to heat, moisture and outdoor operating conditions.
During the initial inspection, Nicco Engineering’s Belzona service engineers observed severe deterioration across several sections of the pipeline. The original coating had broken down, exposing the metal substrate to continuous corrosive attack.
More critically:
- Extensive surface corrosion was visible along the air line.
- Localised pitting had developed at several locations.
- Considerable metal loss was observed in the affected areas.
- Some sections had deteriorated to the point of developing air leaks.
- The remaining pipeline wall was significantly weakened at critical locations.
The condition of the line made conventional abrasive surface preparation particularly challenging. Aggressive blasting or mechanical preparation of the already thinned pipeline presented a risk of further damaging the substrate and potentially enlarging existing perforations.
The plant therefore required a cold-applied repair solution capable of rebuilding the deteriorated areas and protecting the pipeline against continued environmental corrosion.
The Conventional Solution
The conventional approach would have involved identifying the severely corroded sections and replacing the affected pipework.
This could have required:
- Isolation of the air line.
- Cutting and removal of damaged pipeline sections.
- Fabrication and installation of replacement pipework.
- Welding and associated hot work controls.
- Inspection and testing before returning the line to service.
Apart from the cost of replacement, the process could significantly increase maintenance time and introduce additional operational and safety requirements within the plant.
Applying a conventional protective coating alone was also not considered sufficient. The pipeline had already suffered substantial metal loss and deep pitting, meaning the deteriorated areas first required rebuilding before an environmental protective coating could be applied.
Why Belzona Was Recommended
The Belzona system was recommended because the repair required more than simply painting the corroded pipeline.
The service engineers needed a solution capable of addressing two separate problems:
1. Restoring deteriorated and pitted areas of the pipeline
Belzona 1161 was selected as the repair material to rebuild areas affected by corrosion and metal loss.
2. Providing long-term environmental corrosion protection
Belzona 5841 was selected as the protective coating system for the repaired pipeline, helping provide a barrier against the heat- and moisture-related environment responsible for the original deterioration.
Most importantly, the cold-applied Belzona repair approach enabled the engineers to restore the affected sections without welding or extensive replacement of the pipeline.
The Belzona Solution
A combination of Belzona 1161 and Belzona 5841 was used to restore and protect the damaged air line.
Belzona 1161
The material was applied to the severely deteriorated areas to rebuild the damaged substrate, fill corrosion pits and restore the profile of the affected pipeline sections.
Particular attention was given to areas where extensive corrosion and localised leakage had been identified.
Belzona 5841
Following the repair of the deteriorated areas, Belzona 5841 was applied as the protective coating system.
The coating provided a barrier between the pipeline substrate and the surrounding environment, helping protect the repaired air line from further corrosion caused by persistent moisture and elevated environmental temperatures.
Application Process
The application was carried out by Nicco Engineering’s trained Belzona service engineers.
1. Initial Inspection
The complete affected air line was inspected to identify:
- Severely corroded sections.
- Areas of localised pitting.
- Locations showing substantial wall loss.
- Active leakage points.
- Areas requiring rebuilding and protective coating.
The inspection confirmed that aggressive surface preparation was not advisable at several locations because of the reduced remaining metal thickness.
2. Controlled Surface Preparation
The affected sections were carefully prepared to remove loose corrosion, degraded coating and surface contamination.
Unlike a conventional coating application where extensive abrasive blasting may be possible, the preparation process had to be carefully controlled due to the fragile condition of the remaining pipeline wall.
Care was taken not to further damage the severely thinned substrate.
3. Rebuilding with Belzona 1161
Belzona 1161 was applied to the deteriorated sections of the air line.
The material was used to:
- Fill deep corrosion pits.
- Rebuild areas affected by substantial metal loss.
- Restore the profile around damaged pipeline sections.
- Reinforce the locally deteriorated areas prior to protective coating.
The material was carefully formed around bends, joints and irregular pipeline geometries to achieve complete coverage of the required repair areas.
4. Protection with Belzona 5841
Following completion of the rebuilding work, Belzona 5841 was applied to the prepared and repaired pipeline surfaces.
The coating system created a continuous protective barrier over the air line, isolating the substrate from the environmental conditions that had contributed to the original corrosion.
The Outcome
The Belzona repair system successfully restored the severely corroded air line without the need for extensive pipe replacement or welding.
The completed repair:
- Rebuilt areas affected by severe pitting and metal loss.
- Addressed the locally deteriorated and leaking sections.
- Restored the profile of the damaged pipeline.
- Provided environmental corrosion protection to the repaired surfaces.
- Avoided extensive cutting and replacement of the affected air line.
- Offered the plant a practical cold-applied repair alternative.
The before-and-after condition of the pipeline clearly demonstrates the extent of deterioration and the transformation achieved using the Belzona composite repair and protective coating system.
From a severely corroded, pitted and leaking air line to a rebuilt and protected pipeline—the repair demonstrated how the correct combination of Belzona materials can address both existing metal loss and the environmental conditions responsible for corrosion.
