This section contains typical electrochemical corrosions processes related to fasteners and the solution to minimize the corrosion rate. Note, that only the neutral salt spray test, according to ISO 9227, is the premise for evaluating the performance of coatings in conjunction with ISO 4042 and ISO 10683. According to ISO 14713-1, hot dip galvanized products can be estimated to years of lifetime. The coating system in table 2, 3 and 4,all refers to High - the same is applicable for table 4. Keep in mind, that there are not rules that link the durability range and the guaranteed time. The durability range is not a guaranteed time - it is a technical planning parameter. The lifetime of a coating-system is calculated as the period of the time, which passes until maintenance is required for the first time after application. Table 1 gives an overview of corrosion categories and environments. These are depending on the thickness loss of low-carbon steel. The latest edition of EN 12944-2 describes corrosion categories ranging from C1 to CX (CX is covered by ISO 12944-9 and is replacing the offshore ageing test from ISO 203402). The term corrosion category is known from EN 1090-2 and the 12944 series. Reference: GL - Guidelines for Corrosion protection and coating systems of August 1, 2010. Note that special requirements may be applicable due to different regulations such as foodstuff, pressure directive etc. In some places, the recommendations are taken from cited sources.
The content of this document is direct recommendations and rules taken from normative standards. Hence, the document is a guideline - the chosen solution is the responsibility of the designer. Mechanical Engineer - Technology Specialist Fastenersĭisclaimer: Corrosion is a highly complex area, which has been simplified in this document in order to provide easy choices for designers. The focus on corrosion resistance of fasteners is increasing as the commercial aspects of having corroded fasteners are pushing towards smarter solutions.Ĭorroded fasteners can both be a cosmetic and a structural issue, which can result in additional maintenance or even replacement of the corroded component.īoth scenarios generate additional work due to replacement of components, in the end affecting the overall commercial aspect of the construction. The corrosion and the corrosion rate depend on many different parameters, application and environmental conditions, material properties, stress and strain effects and effectiveness of the protective measures all have an influence on corrosion1.
It is only possible to minimize the corrosion rate and the consequences. Well knowing that corrosion as a mechanism cannot be prevented entirely. This document serves as a guideline for engineers and designers who need to choose a proper surface protection system for fasteners.