Wednesday, September 9, 2009

Corrosion Problem

Corrosion has always been a major problems for petrochemical, chemical and process plants. Recent use of more aggressive chemicals and higher temperature and pressure has accelerated corrosion rates in most plants. The problem is acute because corrosion causes leaks, and increasingly stringent environmental and safety laws have made almost any kind of leak unacceptable.

The problem can be approached in several ways:
  1. Modify the condition and environment under which the corrosion take place.
  2. Change the material that is subject to corrosion
  3. Separate the materials from the corrosion environment
  4. Use a combination of the above.
Protective coatings are the most common answer for controlling atmospheric corrosion. When the coating fails, the maintenance costs consist of removing the old coating, preparing the surface for the new coating and applying it.

While preventive and predictive maintenance technologies are helpful for deterring corrosion. Priorities and scheduling are important when using protective coating to control corrosion. For example, early touchup and reapair prevent further corrosion and limit cost.
The general rule is to touch up the surface when 15 percent to 20 percent of it has failed. If 30 percent or more has failed, it is more economical to completely repaint rather than touch up.
Additional ways to reduce corrosion costs are as follows:
  • Promote corrosion control in the plant's quality improvement programs so that the discipline receives more attention.
  • Encourage maintenance staff people to keep up with trade literature and attend conferences and seminars to stay informed.
  • Draw on contractor's knowledge on how design and fabrication influence corrosion. Coating contractors have access to much information on corrosion and should be consulted about selecting protective coatings.
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