Abstract

In 2000, the US Naval Research Laboratory (NRL) for Corrosion Science & Engineering began work on the Future Naval Capabilities’ Single Coat Program. The program aimed to reduce corrosion damage and maintenance time by replacing legacy, solvent-based coatings with high solids, single coat, rapid cure, MIL-PRF-23236D Type VII high solids epoxy coatings to the fleet.

In 2005, a US Navy ship's seawater ballast tank coating had failed and needed replacement. The failed coating (applied in 1996) was replaced by a 100% solids epoxy coating system and the ship was returned to service. Follow-up inspections on the coating's performance were conducted 15 months, 7.5 years, and 15.5 years after the lining was applied.

The 100% solids, single coat epoxy coatings system demonstrated that it was meeting the Navy's goals of minimizing failures and reducing maintenance costs.

Introduction

In the mid-1990s, the US Navy's technical community, led by Naval Sea Systems Command (NAVSEA), recognized existing coatings used to protect the inside of ships' tanks were failing on average 5-8 years after application. The high cost to blast and recoat over 11,000 tanks every 5-8 years, not counting submarines and aircraft carriers, was prohibitive. To address this issue, the Navy conducted a study to analyze the problem and decided to replace these legacy coatings with high solid epoxy coatings.1

Consequently, NAVSEA mandated high solid epoxy coatings in the tanks of ships, which would last 20 years. Initially, these coatings were referred to as high solids epoxy coating systems. Over time the high solids developed into ultra-high solids (UHS) and eventually 100% solids epoxy products.1

Many of these tanks were inside of ships that are now decommissioned, but not all. Over 100 tanks with high solids coatings are estimated to still be in service. The Navy is currently collecting data on the condition of those tanks and looking to identify if the coatings lived up to the 20-year service life mandated by NAVSEA. Initial reports indicate that they have. Verbal reports from Navy officials indicate that high solid epoxy coatings have met the 20-year service performance criteria. It should be noted that NAVSEA refers to these coatings as single coat, rapid cure, MIL-PRF-23236D Type VII coatings.

They do not make the distinction of the volume of solids content. The industry, however, offers the following distinctions:2

High Solids: 50-60% solids

Ultra-High Solids: 90% solids

100% Solids: no solvents

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