The use of duplex coating systems (hot dip galvanizing or thermal spray coating with one or more liquid-applied coatings) for long term protection of structural steel is becoming more mainstream in many industries. This paper describes the advantages of employing duplex coating systems as well as some important considerations for designers prior to specifying their use. It also highlights an ongoing initiative to help agencies more efficiently and effectively use duplex coatings on steel bridges by developing guidelines, standards, and other materials.
Being proactive and performing scheduled coating condition assessments on above ground storage tanks to prevent corrosion is of utmost importance to protect assets. Undetected corrosion can result in product contamination, section loss, create compliance issues resulting in fines levied by governmental agencies, and increase costs of asset replacement. Planned and detailed coating/lining condition assessments can help a tank owner realize the current condition of their assets and maximize life expectancy.
It has become common practice for specification writers to require minimum tensile pull-off adhesion strength values as part of the acceptance criteria for protective coating work for concrete substrates. These values are convenient for specifiers because a minimum number provides a black and white basis upon which to define success versus failure. But there is much more to performing and evaluating adhesion testing than a hard and fast number.