Zero VOC, Coal Tar Free Splash Zone Coating (SZC)
Abstract
The splash zone is defined as the area between the year s lowest tidal mark and up to 10 feet above the year s highest tidal mark. It is extremely difficult to protect steel structures against corrosion in this zone where corrosion rates have been documented to exceed 30 mm per year on unprotected steel. This is more than six times the corrosion rate typically found on steel under constant water immersion. Specific guidance for coating the Navy s steel sheet piling employs two coating system options for the initial painting of steel placed in seawater immersion/splash zones: 1) three coats of epoxy-polyamide or 2) two coats of coal tar pitch epoxy-polyamide. In theory, the three-coat epoxy system should provide better in-place service than the two-coat coal tar epoxy system. In practice, the coal tar system is used almost exclusively due to the lower material cost. The coal tar system provides approximately five years of splash zone service before maintenance is required which can include complete removal and reapplication. However, maintenance is rarely done due to the high cost and environmental issues that need to be addressed. The environmental issues associated with the two coating system options include high volatile organic compounds (VOC) content, hazardous air pollutants (HAP), and may also include hazardous pigment content. The coal tar epoxy also contains coal tar pitch which is regulated by the Occupational Safety and Health Administration (OSHA) due to known human carcinogen content. The product developed under this effort is 100% solids and therefore has no VOC content, has no coal tar pitch, and exceeds the field performance of the two current coating system options.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2011
- Accession Number
- ADA580145
Entities
People
- Daniel A. Zarate
- David E. Pendleton
- David Gaughen
Organizations
- Environmental Security Technology Certification Program