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From the cases of atmospheric corrosion and the conditions that are conducive to such corrosion we have formulated a number of preventive measures. They are taken at three different points in time, during the:
- Engineering phase;
- Construction phase;
- Maintenance phase.

The preventive measures during the Engineering phase and the Construction phase have been covered in UreaKnowHow.com Mechanical Paper of September 2009. This paper covers the preventive measures during the Maintenance phase.

Conclusions

* Atmospheric corrosion is a serious threat to the safe operation of, especially older, (petro) chemical process plant.
* If a hazardous situation might arise or if there is a risk of production outage, preventive / predictive maintenance with respect to external corrosion, should be carried out rather than breakdown maintenance.
* Conditions promoting atmospheric corrosion as well as requirements regarding preventive measures should be laid down in adequate standards.
* Application of painting systems and insulation systems if necessary, should be performed according to the requirements in these standards regarding product quality as well as guidance and control.
* Adequate protective coatings can extend the safe running period of (petro) chemical plant by as much as ten years. Extension by at least another ten years is possible by implementing a consistent inspection and maintenance programmed.
* Experiences show that application of a thermal spray aluminium coating generally requires minor maintenance. Despite higher investments costs it is expected that in many cases the life cycle costs are lower. For that reason application of thermal spray aluminium coating is promoted more and more to combat atmospheric corrosion of carbon steel piping and equipment.
* It is essential that management is aware of the risk and consequences of atmospheric corrosion. That awareness should be transferred to the workforce via communication programmed, training and a detailed corrosion control plan.
* The Guided Wave Piping Inspection Tool (“long range ultrasonic inspection”) is a promising non destructive testing method for inspection of (insulated) piping with just local removal of insulation. However, improvements in accuracy have to be developed.
* More research is needed for developing reliable inspection and monitoring techniques for insulated piping and equipment.
* A corrosion control (inspection and maintenance) plan has to be developed, based on RBI (risk based inspection) philosophy. This plan should comply with the work process of IER (Improve Equipment Reliability) according the manufacturing excellence philosophy.