Any construction professional undertaking an outdoor project will know that, apart from competitors or budget constraints, nature can very often be the most difficult opponent to contend with. Whether it’s the scorching sun, wet rain, or salt-rich winds from near the ocean, nature is always at work undermining any construction process by degrading any given material. Where emphasis naturally focuses upon larger structural elements when planning an outdoor project, it’s very often these smallest elements which can make or break any given structure: its fasteners.
Taking account of a specific risk associated with corrosion in the outdoors can easily result in a disaster. It is not just a concern of some aesthetic ironwork staining a building facade. It is a concern of safety and a life span associated with a building or a structure. To comprehend a process of corrosion and how to apply a proper fastening solution to your structure is an irrevocable skill in high-quality construction.
Types of Corrosion Affecting Fasteners
It can thus be said that corrosion refers to the natural process through which highly refined metals transform themselves into a more chemically stable form, like sulphides and oxides. When it comes to the topic of fasteners, the degradation of metal generally happens through one of the forms of corrosion.
It is important for constructors to note that galvanic corrosion can be a problem for them. This can occur if two different metals are in contact and an electrolyte is present in that environment. The use of stainless steel screws in an aluminium sheet without an insulating washer can lead to faster corrosion of the aluminium sheet, for instance. Another form of corrosion that constructors should note is crevice corrosion that can occur in a protected area where water may accumulate.
Materials Resistant to Corrosion
This is the first line of protection against the elements. Stainless steel is still considered the gold standard among outdoor fastening systems because of its natural rust-resistant properties. It has chromium components that react with the atmosphere to develop an oxide skin, thus repelling more moisture.
Within the group of stainless steels, the type has a great influence. If one is required to choose between 304-grade and 316-grade materials for a construction that is erected near the ocean or in an industrial setup, it would be highly recommended to opt for the 316-grade materials. The additional element of molybdenum in the 316-grade materials helps to significantly resist corrosion caused by chlorides in sea spray.
Coatings and Treatments for Enhanced Resistance
In cases where it is not possible to use solid stainless steel due to economic reasons or strength constraints, carbon steel with specialised coating could be a good substitute for the above-listed materials. Hot-dip galvanising is one of the most efficient means of protecting steel. This process includes dipping the steel into a pool of liquid metals like zinc.
Another type of protection that might be employed could be zinc plating. However, usually it has less thickness of protection compared to hot dip galvanising. In addition to that, these processes are usually better suited to less severe environments. The other advanced processes that could be applied to it could be proprietary ceramic coatings or flake coatings. These are usually resistant to thousands of hours of salt spray testing.
Best Practices for Selecting Corrosion-Resistant Fasteners
The selection of a fastener is a much more complex process than merely selecting a material. Prior to choosing a material for a fastener, one must consider the environment surrounding their project. Corrosiveness is the first thing one must consider for their project environment. A project situated five miles from the coastline presents a vastly different environment than a pier project or a beach house.
It is important that the lifespan of the structure in question is taken into consideration. Since the structure is expected to last for a period of fifty years without any maintenance, the use of low-grade galvanised screws is not cost-effective. In addition to that, the matter of compatibility is crucial in avoiding galvanic corrosion. Always make sure that the metal used is compatible with the other metal, or use isolation washers.
Building for the Long Haul
The lifespan of any outdoors installation is significantly dependent on the quality of the connections made. With the ability to understand the chemistry battles occurring on the surface of your fasteners, you can successfully avert expensive repairs in the future. From making the right choice between marine-grade 316 stainless steel or hot-dip galvanised, it is fundamental to match the specification of the installation with the surroundings, and top machine screw suppliers, for instance, can help with this. When the small things are done correctly, the remainder of the installation will be strong for many decades!
