Galvanizing Bolts FAQs
What Makes Marine Fasteners Different From Other Fasteners?What are Marine Fasteners?
The purpose of using a marine fastener versus other fasteners is to withstand corrosive saltwater and other harsh marine environments. Marine fasteners are commonly made from stainless steel or carbon steel which has a corrosion-resistant coating applied to it. The reason that these materials would be preferred over other common fasteners is that they offer... Read more
Heat-treatment After ForgingDo headed bolds receive heat treatment before or after the heads are forged?
Not all grades of bolts require heat-treating, but those specifications that do are heat-treated after the heads are forged. Heat-treating is performed in a controlled environment using specific quenching and tempering temperatures and durations. The bolts are then tested to ensure the strength of the heat-treated bolts meet the requirements of the given specification. Since... Read more
Can A490 bolts be galvanized?Can A490 bolts be galvanized?
The ASTM F3125 Grade A490 specification does not allow either hot-dip galvanizing (per ASTM F2329) or mechanical galvanizing (per ASTM B695) due to the risk of hydrogen embrittlement. The only coating currently allowed on A490 bolts is a zinc aluminum coating meeting any of the following specifications: ASTM F1136, F2833, or F3019. ASTM Committee F16... Read more
Galvanizing A320 Grade L7M BoltsCan 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 StudsCan 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 StainsWhat 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 B7MCan 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 GalvanizingDoes 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 Coating LifespanWhat 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 NutsWhat 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