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2026-11-03T09:18:26

Hot-Dip Galvanizing Thickness Under ISO 1461: 85 µm, 70 µm and How to Check

热浸镀锌层厚度ISO 1461：85微米、70微米标准与验收方法

Hot-dip galvanizing thickness on fabricated steel is set by EN ISO 1461:2022 and depends on the steel thickness. For steel over 6 mm, the mean zinc coating must be at least 85 µm with no reference area below 70 µm; for 3–6 mm steel, 70 µm and 55 µm. Checking takes only a magnetic gauge, so buyers of fences, canopies or steel frames can ask for it at handover.

Key Facts

What ISO 1461 covers

EN ISO 1461:2022 applies to hot-dip galvanizing of fabricated steel, sections and castings dipped in molten zinc of at least 98% zinc content. It excludes products coated in automated or semi-automated lines, such as sheet, wire and tube. So for zinc-coated roofing or factory galvanized pipe, the reference is each product's own standard, not ISO 1461.

The standard covers surface requirements, post-galvanizing inspection, coating uniformity, limits on uncoated areas and their repair, adhesion, acceptance criteria and the declaration of compliance.

Local and mean: two different numbers

Local thickness is the average of readings in one reference area. Mean thickness applies to the whole article. No reference area may fall below the local figure, and the whole article must reach the mean figure. Example: an 8 mm canopy base plate needs a mean of at least 85 µm with no reference area below 70 µm.

How many samples are tested

  • Lots of 1–3 items: all tested.
  • 4–500 items: at least 3.
  • 501–1,200: 5; 1,201–3,200: 8; 3,201–10,000: 13; over 10,000: 20.

If the sample fails, a sample twice the size is tested. If that passes, the lot is accepted; if it fails again, the lot is rejected.

How to check on site

  • Use a magnetic coating thickness gauge (ISO 2178), the non-destructive method the standard encourages. The gravimetric test (ISO 1460) remains the referee method in disputes.
  • Inspect visually: the coating should be continuous, reasonably smooth and free of flux staining on accessible surfaces. The standard has no aesthetic requirements, so dull or patchy colour is not grounds for rejection.
  • White wet storage stain from damp is also not grounds for rejection as long as local thickness is still met.
  • Uncoated areas up to 10 cm² may be repaired with zinc-rich paint, low-melting zinc sticks or thermal zinc spray (ISO 2063). Larger areas should normally be regalvanized.
  • Bending after galvanizing is not normal handling and can damage the coating.

Tips for ordering galvanizing work

Write "hot-dip galvanized to EN ISO 1461" on the purchase order, state the steel thickness and ask for a declaration of compliance (ISO 10474) if needed. Some steels with very low silicon (≤ 0.01%) and aluminium above 0.035% struggle to reach the minimum, so the standard allows the next lower thickness category provided it is recorded in the declaration.

homeX, an integrated building materials and furniture platform in Indonesia with showroom, warehousing and delivery services, can help source steel materials and galvanized fencing to project specifications.

Hot-dip galvanizing thickness: related articles and products

FAQ

What is the standard hot-dip galvanizing thickness? Under EN ISO 1461:2022, steel over 6 mm needs a mean of at least 85 µm (70 µm local); 3–6 mm steel needs a 70 µm mean (55 µm local).

Does factory galvanized pipe follow ISO 1461? No. ISO 1461 excludes sheet, wire and tube coated in automated or semi-automated lines; those follow their own product standards.

Should dull or patchy galvanizing be rejected? No. ISO 1461 has no aesthetic requirements; what matters is continuity of the coating and thickness per the table.

For building and renovation material needs, reach the homeX team on WhatsApp +62 821 1818 998, by email at homex9998@gmail.com or through our contact page.

Sources: Galvanizers Association, HDG Datasheet 4b EN ISO 1461:2022 (Oct 2024, accessed 3 Nov 2026)