Understanding A123 & Intended Use
The initial appearance of hot-dip galvanized steel is difficult to predict for a variety of reasons and oftentimes varying surface appearances, textures, or anomalies can result. While most variances do not influence corrosion resistance, they can sometimes fail to meet the aesthetic expectations of architects, engineers, inspectors, contractors, or other involved parties. Since ASTM A123 says interference with intended use is not permitted, this can lead to concerns over calls for rejection if the product did not “turn out as intended.”
The problem here is intended use is different from intended appearance. ASTM A123 is written to ensure durable and corrosion-resistant coatings are produced, taking appearance into account only if it causes problems with the functional features of the product such as required fit-up to other parts, safe handling, or ability to be painted or powder coated. This does not include concerns which are primarily aesthetic in nature.
One example of an HDG coating affecting an item’s intended use is when threads on bolts or fasteners become too thick after galvanizing to mate up with their corresponding nuts. Bolts that won’t mate up can no longer meet their intended use and will require remediation.
Another example of HDG affecting the intended use of an item is when handrails or other frequently handled surfaces develop sharp burrs or ridges of zinc that could harm users. Since the intended use of the item includes being safely handled, the item’s intended use is affected, and these areas must be smoothed until safe handling is achieved.
If needed, rough edges and burrs can be easily remedied or smoothed at the galvanizing facility while other appearance concerns are more difficult to remedy or prevented by the galvanizer and may require the additional implementation of design and fabrication best practices. It’s important to note that while thick or rough coatings can hinder the intended use of some parts, they are perfectly acceptable for other parts that do not need to mate up or need to be smoothed to operate as a safety device.
When the term "intended use" is used as reason for rejection, the question to ask is - Does the HDG coating prevent the part from functioning or operating as it is intended to? If not, then the article is not rejectable and other options should be explored. If needed, the purchaser always has the option to establish final appearance criteria for Architecturally Exposed Structural Steel (AESS) or any other project-specific aesthetic requirements beyond the requirements of A123 as long as these requirements are clearly defined using project specifications and communicated to the galvanizer (subject to mutual agreement).
© 2023 American Galvanizers Association. The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.