Hot dip galvanized vs zinc plated: which do I need?
Both are zinc, and that is where the confusion starts, but they are not close in performance. Zinc plating deposits a thin layer electrically, typically 5 to 25 microns, bright and dimensionally precise but thin enough that outdoor exposure begins working through it within months, particularly near coast or industry. Hot dip galvanizing immerses the part in molten zinc at around 450 degrees Celsius, building a coating of 45 microns upward that is metallurgically bonded rather than simply adhered. That is more than five times the zinc, and because the coating is a reservoir of sacrificial metal, service life scales roughly with thickness. For a lifting fitting living outdoors, that difference decides the specification.
Why choose hot dipped galvanized eye nuts
- Coating thickness of 45 microns and up, against 5 to 25 for zinc plating
- Metallurgically bonded zinc-iron alloy layer, not a surface deposit
- Decades of outdoor service where plated finishes fail in months
- Self healing, since zinc forms a protective carbonate over minor scratches
- Lower lifecycle cost outdoors, with less inspection and replacement
- Suited to marine, coastal, and industrial atmospheres
Sizes stocked
- 3/8-16 for lighter general purpose rigging
- 1/2-13 the most commonly specified size
- 3/4-10 for heavier lifting points
- Thread engagement should be at least one bolt diameter in steel
- Seat the nut squarely on a flat surface or hardened washer
Common applications
- Outdoor lifting points on plant and equipment
- Marine and coastal rigging exposed to salt air
- Industrial atmospheres with airborne chemical exposure
- Permanent installations where maintenance access is limited
- Agricultural and construction equipment left outdoors
- Any lifting fitting expected to serve for years without recoating
For indoor and dry service where cost matters more than coating life, zinc plated Style A eye nuts are the economical option. Where chloride exposure is severe or appearance matters, 316 stainless avoids coatings entirely.
Related Categories
Hot Dipped Galvanized Eye Nut FAQs
Will the thicker coating affect thread fit?
It can, and this is the practical tradeoff with hot dip galvanizing. The coating adds real dimension, which is why galvanized nuts are typically tapped oversize to accommodate it. If you are pairing with a galvanized bolt, the two are designed to work together. Mixing a galvanized nut with a plain or plated bolt can leave the fit looser than intended.
How long will the coating last outdoors?
Service life scales with thickness and environment. In typical outdoor atmospheres, hot dip galvanized steel commonly runs decades before first maintenance. Coastal and heavy industrial exposure shortens that, but it remains far longer than a plated finish would give.
What is the white powder that forms on galvanized parts?
Zinc oxide, sometimes called white rust, which forms as the zinc weathers. In moderate amounts it is a protective layer that adds to corrosion resistance rather than indicating failure. Heavy accumulation in wet storage is a different matter and suggests parts were stacked damp without ventilation.
Does galvanizing affect the eye nut's rating?
The coating process involves heat, and any effect on mechanical properties depends on the base steel and how it was manufactured. Use the manufacturer's published rating for the galvanized version rather than assuming it matches the plain steel equivalent.
Can I use these with stainless hardware?
In dry conditions yes, but with moisture present the galvanized coating becomes sacrificial against stainless and will be consumed faster than it otherwise would. For mixed metal assemblies outdoors, consider stainless throughout.
What are the general rules for using eye nuts?
Thread engagement of at least one bolt diameter in steel, seated squarely on a flat surface or hardened washer, and loaded in line wherever possible. Side loading reduces capacity substantially and requires derating. Follow the manufacturer's load chart and inspect before every lift.