If you run an industry where you have to use a large number of fasteners for any reason, it’s always important to pay attention to how you use them to reduce the chances of complications. Whether you are making products for industrial or retail use, a high incidence of fastener failure is something that can […]

If you run an industry where you have to use a large number of fasteners for any reason, it’s always important to pay attention to how you use them to reduce the chances of complications. Whether you are making products for industrial or retail use, a high incidence of fastener failure is something that can eventually erode the trust that clients have in your products. In the end, you might end up losing all your business.
One of the specific issues you need to address is how to ensure that the fasteners you use will not corrode over time. There are many ways in which this can happen, but one of the most commonly seen is galvanic corrosion. This typically occurs when you use fasteners such as 316 stainless steel hex nuts without preparing them first.

The basic mechanism of galvanic corrosion
In a nutshell, galvanic corrosion occurs when two different metals are placed in contact with each other and with an electrolyte such as water that is slightly ionized. As a result, one of the metals will become oxidized, and the other will become reduced. A good example of this is when you use 316 Stainless steel hex tap bolts to fasten items that are made of aluminum, and then placing them in the outdoors. In this example, the aluminum will start corroding as a result of the chemical reaction.

 
This then means that when one has to use fasteners to join materials of a different metal type, they would need to take into account the risk of galvanic corrosion, particularly if the entire ensemble will be subjected to all forms of moisture from dew to rainwater.
How is it prevented?
Theoretically, the best way to prevent this type of erosion is by making sure that fasteners are made of the same metal as the material they are used to fasten. However, this is not always practical. If the two have to be different, some of the measures one can take to reduce the risk of corrosion include application of protective coatings on the fasteners through electroplating and powder coating. The goal of doing this is to reduce contact between the two bodies, so it would be wise for you to use thicker coatings to encourage this.
In addition to that, you might also need to carefully choose the metals used in such a setting. Even if the fastener and the item being fastened are made of different types of metal, making sure that they are of close nobility will reduce the rate of corrosion. This usually needs a working knowledge of the atomic properties of the metals. However, it’s important to keep in mind that zinc and steel are the farthest apart in terms of nobility, so placing them in contact would result in the highest rate of corrosion.
As you can see, this also means that when you are choosing fasteners you can use for a metallic object, you can’t afford to be random about it. Always try to account for galvanic corrosion to achieve the best results.

About the Author

Larry Melone
By Larry Melone
President

Started my career in the fastener world in 1969 at, Parker Kalon Corp. a NJ based screw manufacturer located in Clifton, NJ working in inventory control, scheduling secondary production and concluding there in purchasing. In 1971 I accepted a sales position at Star Stainless Screw Co., Totowa, NJ working in inside sales and later as an outside salesman, having a successful career at Star I had the desire with a friend to start our own fastener distribution company in 1980 named: Divspec, Kenilworth, NJ. This was a successful adventure but ended in 1985 with me starting Melfast in August 1985 and have stayed competitive and successful to date. Melfast serves the OEM market with approximately 400 accounts nationally.

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