|7. Coating Failures|
7.2 Factors Contributing to Coating Failures
1. Exposure Conditions
The interaction of coating with the environment is of prime importance as it is the basic factor which leads to coating failures.
The following factors related to exposure are major contributors to failures of coatings
Marine environment, proximity to sea water
Rural atmosphere: sandy areas, hill backs, marshes, hot springs, etc.
Abrasive atmospheres: sandy areas with high wind speeds, areas with intermittent rainfall.
Temperature: Temperature in subzero and in excess of 40oC.
Water immersion: Structure and equipment exposed to brackish, sea, or spring water.
Chemicals: Equipment and structures, tanks, etc. exposed to corrosive chemicals.
Petroleum products: Storage tanks for petroleum products and oil, pipelines, transporting crude oil, petroleum products, etc.
Internal environment: Internal dry, damp and wet environment in plants and equipment.
Specification: Compliance with specifications by manufacturer.
Training: Training coating applicators and inspectors.
Important conditions affecting coating quality:
Dew point (temperature at which moisture condenses)
Contamination (sand or salt particles among other contaminants)
The compatibility of the coating must be checked for the above conditions to ensure a failure-free life of the coating.
It is important to check the pigment/vehicle ratio, the correct ratio of thinners, and the correct curing period.