NA 900 pipeline transporting waste gases to torch chimney had serious corrosion because of corrosive diluted gases on the bottom part. Emergency repair was needed due to operational problem which would normally mean a costly emergency shutdown.
The repair was completed whilst the pipeline was still in service and for this reason it was only possible to make exterior repairs to extend the life of the pipeline until a scheduled shut down could be undertaken to replace the section or effect remedial works on the inside giving direct protection from the corrosive liquid.
All materials used for the repair were resistant to the conditions and thus they would provide a medium term solution although it would still be the case that the metal would be attacked on the inside of the pipeline and would ultimately corrode through outside of the repair area. The repair enabled several months of additional life and prevented a costly emergency shutdown which would be the only other solution.