Galvanizing Bolts FAQs

Galvanizing A320 Grade L7M Bolts

Can A320 Grade L7M bolts be hot-dip galvanized?

The A320 Grade L7M is a variation of the A320 Grade L7 specification used in low-temperature, low-pressure applications. Nowhere in the A230 specification does it discuss whether or not A320L7M fasteners can be galvanized. In theory, there is nothing preventing someone from galvanizing the material, however, the L7M designation comes from heat treating being the... Read more

12′ Galvanized All Thread Rod Cut into Studs

Can 12 foot lengths of galvanized all thread rod be cut into studs?

Yes, 12’ sticks of hot-dip galvanized all thread rod can not only be cut to smaller lengths, but it is often preferred. Depending on the application, all thread rod studs vary in length. For this reason, it is most common for all thread rod to be stocked in 12’ sticks, which can then be cut... Read more

Wet Storage Stains

What is a wet storage stain?

A wet storage stain is a white, rust-like surface discoloration that occurs from storing newly hot-dip galvanized materials.  Wet storage stains occur when recently hot-dip galvanized materials are subjected to a moisture-rich environment and/or the materials are packed so closely together that there is not enough air movement and oxygen for the parts to “breathe”.... Read more

Galvanizing A193 Grade B7M

Can A193 Grade B7M bolts be hot-dip galvanized?

A193 Grade B7M is a grade variation of the common A193 Grade B7 used in high-temperature, high-pressure applications. Nowhere in the A193 specification does it discuss whether or not A193B7M fasteners can be galvanized. In theory, there is nothing preventing someone from galvanizing the material, however, the application in which these bolts are intended to... Read more

Partial Galvanizing

Does Portland Bolt partially galvanize anchor bolts?

Yes. Portland Bolt can partially galvanize an anchor bolt. However, it is far more common for anchor bolts to be fully galvanized. If hot-dip galvanizing is required, engineers sometimes specify that only the exposed, projecting end of an anchor bolt should be galvanized, while the rest of the anchor bolt that gets embedded into concrete... Read more

Galvanized Bolts

Galvanized Coating Lifespan

What is the life span of the hot-dip galvanized coating of a bolt?

A common question when deciding whether hot-dip galvanizing is an adequate corrosion resistant coating for a fastener is, “How long will the galvanizing last before the steel begins to corrode?” The last thing you want to do is install a bolt in a corrosive environment, only to have it begin to rust a year later. Unfortunately... Read more

Overtapping Mechanically Galvanized Nuts

What are the overtapping allowances for mechanically galvanized nuts?

The overtapping allowances for mechanically galvanized nuts are the same as overtapping allowances for nuts that are hot-dip galvanized. Mechanically galvanized nuts that adhere to ASTM B695 are “cold-galvanized,” which implies that they are coated with zinc at room temperature. Neither electricity (electroplate galvanizing) nor heat (hot-dip galvanizing) are applied in a mechanically galvanized process.... Read more

Mixing Finishes on Nuts and Bolts

Can I use a mechanically galvanized nut with a hot-dip or electroplate galvanized bolt (or vice versa)?

No, mixing and matching different types of galvanized products is not advised. From ASTM A563/A307/A354 and F1554: “4.7.4 When no preference is specified, the supplier may furnish either a hot-dip zinc coating in accordance with Specification F2329, or a mechanically deposited zinc coating in accordance with Specification B695, Class 55. Threaded components (bolts and nuts)... Read more

G90 vs F2329 (A153)

How is G90 galvanized steel different from F2329 (or A153) hot dip galvanized steel?

Both are produced via the hot dip process, but with slightly different processing steps. G90 is a coating grade within the steel sheet specification ASTM A653, and is produced by uncoiling steel coils and running it at high speed through the pickling process and molten zinc before it passes through an air curtain, which creates... Read more

Galvanizing F1554 Anchor Bolts

Can all three grades of F1554 anchor bolts be galvanized?

The answer to this question is yes! All three grades within the ASTM F1554 specification, Grade 36, Grade 55, and Grade 105, can be either hot-dip galvanized or mechanically galvanized.  The issues of hydrogen embrittlement and/or mechanical properties being alerted during galvanizing are not an issue with any of these three grades.  In Section 7... Read more