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STANDARDS
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The basic specification for hot dip galvanized coatings on iron and steel articles is defined by a single standard, BS EN ISO 1461 "Hot dip galvanized coatings on iron and steel articles - specifications and test methods".
The galvanizer acts as a specialist subcontractor to a steel fabricator and, as such, his contractual relationship is with the fabricator, not with the ultimate user. It is important, therefore, that the user's requirements for galvanizing are made clear to the fabricator and that all communications concerning galvanizing are channelled through the fabricator. To ensure the best quality and technical back-up service, it should be stated that the work be 'processed by a member of Galvanizers Association'.
When hot dip galvanizing is specified, the surface of the steel is completely covered with a uniform coating whose thickness is determined principally by the thickness of the steel being galvanized (see below).
This is an important advantage of the galvanizing process; a standard coating thickness is applied almost automatically. The actual thickness of galvanized coating achieved varies with steel section size, surface profile and surface composition. Actual coating weights are often much more than the minimum specified in the standard. As coating life expectancy figures quoted are based on the minimum coating thickness they are therefore usually very conservative.
The requirements of BS EN ISO 1461 include cleaning and preparation of steelwork as well as galvanizing. Guidance on the use and performance of hot dip galvanizing is contained in BS EN ISO 14713 'Protection against corrosion of iron and steel in structures - zinc and aluminium coatings - guidelines' and further guidance is available from Galvanizers Association.
Relationship between steel thickness and surface area/tonne
The requirements of BS EN ISO 1461 include cleaning and preparation of steelwork as well as galvanizing. Guidance on the use and performance of hot dip galvanizing is contained in BS EN ISO 14713 'Protection against corrosion of iron and steel in structures - zinc and aluminium coatings - guidelines' and further guidance is available from Galvanizers Association.
BS EN ISO 1461: coating minimum masses/thickness on articles that are not centrifuged
BS EN ISO 1461: coating minimum masses/ thickness on articles that are centrifuged
UK NATIONAL BUILDING SPECIFICATION (NBS)
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There are many references to specifying hot dip galvanizing throughout the National Building Specification (NBS) system, the main location being G10 - Structural steel framing. General guidance on corrosion protection is also given.
In the unlikely event of being unable to identify the correct clause for a particular galvanizing application, please contact Galvanizers Association for specific advice.
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