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ZEKER ZINK Handbook

SUMMARY OF THE STANDARD NEN EN ISO 1461

For discontinuous hot-dip galvanizing, it is important that there is good consultation between the galvanizer and the client/client. The galvanizing standard EN ISO 1461 describes the functional requirements for the anti-corrosion action of the applied zinc coating.
For the sake of quality and safety during the galvanizing process, the structural requirements of EN ISO 14713 parts 1 and 2 must be met (poster: “good and safe galvanizing“). The standard also describes the importance of the choice in steel composition (part 2, table 1). The molten and therefore liquid zinc in the zinc bath consists of at least 98% pure zinc.

HECHTING

Discontinuous hot-dip galvanizing is more than just applying a layer of zinc to steel. It is a metallurgical process that creates a zinc-iron alloy that results in optimal adhesion.

CONDITIONALLY PERMITTED

  • Zinc corrosion (white rust), as long as the minimum layer thickness is achieved(see Figure II)
  • Effects as a consequence of intermittent welding(see Figure III)
  • Thickening if the purpose of use is not adversely affected
  • Some unevenness(see Figure IV)
  • Zinc shafts as long as they do not adversely affect corrosion resistance or the purpose of use(see Figure V)
  • Surface roughness due to over rolling(see Figure VI)
  • Sharp points if they cannot cause injury
  • Dark and light staining due to steel compositions (see Figure IX).
  • Flux residues as long as they do not adversely affect corrosion resistance or the purpose of use. In some parts and depending on part design, it is not always possible to remove flux residues.

LAYER THICKNESS CONTROLS

  • Checks for layer thickness are performed using one of the magnetic methods according to ISO-2808 and ISO 2178 (both described in ISO 3882).
  • A reference area covers at least 10 cm2. At least 5 measurements must be made within a reference area.
  • Requirements for minimum layer thickness in relation to material thickness
  • There is no maximum layer thickness. Typically, excessive layer thicknesses can lead to reduced cohesion between the zinc-iron alloy layers and should therefore be avoided.
  • For long objects such as construction profiles, measure about 100 mm from both ends and approximately at the center of the profile.
  • Unless otherwise agreed; no measurement will be made on welded parts such as flanges, stiffeners and head and foot plates.

TOUCH UP UNSINKED AREAS

(SEE FIGURE VII)

Unsinked areas in total should not exceed 0.5% of the total area.

  • An unsinked spot should be no larger than 10 cm2
  • Updating can be done using one of the methods below:
    • Zinc-rich paint that can provide cathodic protection in addition to barrier action(see Figure
      VIII),
    • Zinc spraying (ISO 2063),
    • Suitable products with zinc flakes or zinc paste,
    • Zinc alloy rod.
  • The layer thickness on the touched-up areas should be at least 100 μm, unless otherwise agreed. For example, if the thickness of the repair layer should be approximately the same as the zinc layer thickness
    of the surrounding surfaces.
  • Updating may also have been otherwise agreed with the customer.

Rejected objects must be touched up or re-galvanized according to Section 6.3 of the standard unless otherwise agreed.

INFORMATION TO BE PROVIDED

By Principal:

  • The number of the standard according to which the assignment is to be performed (ISO 1461).
  • Base metal composition.
  • Indication of relevant surfaces, possibly supplemented by auxiliary elements (welded-on parts) that are considered relevant and on which reference areas are indicated (for example, if the auxiliary elements are safety critical).
  • Indication of the presence of surfaces cut with laser, cutting torch or plasma jet.
  • A drawing showing where surface imperfections are undesirable
  • Evidence in the form of drawings or photographs in case of internal vents.
  • Other requirements for coating, pretreatment, layer thickness, post-processing.


By galvanization:

  • Declaration of conformity:
    If required, the galvanizing plant must issue a factory declaration according to ISO 10474. A declaration according to a quality assurance system such as ISO 9001 may also be requested.