Specification for Hot Dip Galvanizing
The information below is the coating specification for Hot Dip Galvanizing.
Hot dip galvanizing EN ISO 1461 – Standard
Hot dip galvanizing is a proven coating system providing corrosion protection for steel and is defined by the standard EN ISO 1461 – ‘Hot dip galvanized coatings on iron and steel articles – specifications and test methods’ This covers the cleaning and pre-treatment of the steel as well as the actual galvanizing process. For marine environments a higher coating thickness can be achieved by shot blasting the surface prior to galvanizing.
Technical applicator requirements
The following conditions are necessary for hot dip galvanizing to be applied effectively and efficiently
- The hot dip galvanizing should be applied in accordance with ISO 1461
- The process should be carried out under a robust quality management system which is audited annually to comply with ISO 9001:2009 or equal
- Components should be labelled or identifiable throughout the process ensuring traceability
- The components should be inspected after galvanizing to ensure minimum thickness levels have been achieved and any surface defects have been addressed. This includes the touching up of allowable bare patches using the procedure detailed in ISO 1461
- Materials should be suitably packaged prior to despatch
- The galvanizer should be a member of the Galvanizers Association. This enables the galvanizer to access independent technical advice that can be utilised by the specifier if any issues arise with the coating
Erection and ongoing care
- Care must be taken during handling and installation to ensure the coating is protected from damage
- Materials that are being stored on site should be adequately protected from site operations
- Stacked, galvanized material that is to be stored outside will risk the formation of white rust. This happens when 2 galvanized surfaces are touching and water is allowed to sit between them. If the material is to be stored for any length of time then it should either be stored inside or adequate spacers should be placed between galvanized layers. Covering galvanizing can contribute to white rust as the material is more likely to be at risk of sweating.
Hot dip galvanizing attributes
- The coating is applied to all surfaces, both internally as well as externally
- Superior corrosion protection for exposed or external steel.
- Up to 150 years lifespan with no major maintenance
- Galvanizing is a non-permeable coating that has a higher hardness rating than steel
- Sacrificial protection built in to coating through electrolytic/cathodic protection
- Superior edge protection compared to paint systems
- Factory controlled process producing a repeatable high quality finish
- Allows quicker and easier site erection reducing time on site and site congestion
- Onsite welding can be accommodated with the use of the approved touch up procedure detailed in ISO 1461