Duplex Self-Tapping Screws: Combating Corrosion

One of the biggest issues with metal fasteners is corrosion, which damages the structure of the material and can cause failure of the component, compromising the entire system. There are several methods of combating the problem and one of these is to use fasteners made from a higher grade of stainless steel, such as duplex self-tapping screws.

There are several different types of corrosion, including:

  • Galvanic. This occurs when dissimilar metals are joined, allowing electricity to flow from one to the other
  • Uniform. Metal surfaces that are not properly plated or coated suffer from this type of corrosion, which occurs across the entire surface area
  • Crevice. This appears in small gaps in metal fasteners and is caused by improper ventilation
  • Pitting. Difficult to detect, pitting corrosion involves the formation of tiny, almost invisible holes in a fastener
  • Inter­gra­nular. Occurs in stainless steel that is heated to extremely high temperatures

The screw is an extremely common fastener that is particularly prone to corrosion; this is due to the fact that there are more areas for pollutants to be stored and that the fastener is not easily self-cleaned. Moisture is retained under the screw head and in the slot, increasing the potential for corrosion to occur.

The duplex self-tapping screw is the perfect solution, particularly for marine applications. They are manufactured using grade 318 stainless steel, which is up to three times harder than standard 316, along with displaying much higher PREN values. As well as being ideal for offshore use, they are also perfect for preventing chloride induced corrosion, as with indoor swimming pools. Duplex screws from BS Stainless come in a range of sizes and can be supplied with washers made from EPDM, Polyamide, Neoprene or HNBR.

Find out more about duplex self-tapping screws on the product page and get in touch with our team if you need further information or advice.

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