ISO 1461:2009,Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods. ISO 1461:2009 is available for free download and is shared by rose from the United States. This PDF document can be.
International Standards Organization ISO 1461, Hot Dip Galvanized Coatings on Fabricated Iron and Steel Articles Specifications and Test Methods, is a general galvanizing specification. This specification is essentially equivalent to the American Society of Testing and Materials. (ASTM) A123 and A153. The ISO specification is 15 pages in length and includes 5 appendices. The appendices include information such as required information to be supplied by the purchaser to the galvanizer, safety and process requirements, coating properties, determination of coating thickness, and a bibliography of other referenced specifications.
In comparing the two standards, ISO 1461 and ASTM A123 and A153, there are no major differences. However, small differences do occur. The easiest way to sum up the differences between the two specifications is by comparing the coating thickness requirements in a table. The differences in minimum average coating thickness for most steel articles are small. In the specification, the ISO minimum coating thickness requirements are summed up into one table, which does not mention coating grades and does not require the user to reference two tables as with ASTM A123 . Also, the ISO1461 specification lists minimum local coating thickness to which any one measurement must meet. These are 0.4-0.6 mils thinner than the minimum average coating thickness. In the ASTM specifications, only ASTM A153 has such minimum local thickness coating listed for castings and fasteners. Rolled, pressed and forged articles referred to ASTM A153 also have minimum local coating thickness; these articles are not specifically mentioned in the ISO specification.
After comparing the two, I found that they are very similar, with the ASTM Specs typically requiring more coating thickness on most types and thickens of steel. Therefore, if you can meet ASTM coating requirements, you most likely will meet the ISO 1461 specification, as well.
© 2020 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.
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'.
The basic specification for hot dip galvanized coatings on iron and steel articles is defined by a single standard, EN ISO 1461 ‘Hot dip galvanized coatings on iron and steel articles – specifications and test methods’. However, there are some exceptions to this standard (see thicker coatings below).
BS 729 was the old British galvanizing standard for hot dip galvanizing. It is now superseded by (BS) EN ISO 1461.
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 Graph 1 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.
Graph 1 Relationship between steel thickness and surface area/tonne
Guidance on the design and performance of hot dip galvanizing is contained in EN ISO 14713 Part 1 and 2.
EN ISO 1461: coating minimum masses/ thickness on articles that are not centrifuged
EN ISO 1461: coating minimum masses/thickness on articles that are centrifuged
UK National Building Specification (NBS)
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.
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.
Thicker coatings than those set out in EN ISO 1461 can give additional protection for use in particularly aggressive environments and can be specified in conjunction with EN ISO 1461. It should however, be emphasised that for most applications, thicker coatings are rarely necessary.
Grit blasting prior to galvanizing is usually the most appropriate method and a requirement for a nominal coating thickness of 1000 g/m² (140 µm) has been successfully specified for steel of 6 mm section thickness. For structural steelwork, it is advisable to ascertain whether thicker coatings could be achieved through their greater section thickness and without grit blasting.
Achieving thicker coatings through specification of a reactive steel is normally only appropriate for specific applications.
Specification of thicker coatings must only be made following consultation with the galvanizer concerning viability and the means by which they will be achieved.