Removing Rust from Nuts and Bolts
Rusted equipment can be a serious detriment to any manufacturing shop or industrial product user. Unless it is specially treated with rust-resistant materials, nearly every iron-based component is at risk of rusting, particularly under specific environmental conditions that accelerate this type of deterioration. Although not every form of rust is visibly detectable, any significant accumulation will cause a component to malfunction and eventually fail over time
Rust traditionally refers only to the formation of iron oxides in iron-based metals and alloys, although other types of metal face similar kinds of oxide corrosion. The combination of water and oxygen causes these iron oxides to form a stiff, non-reactive coating along the metal’s surface. As rusted parts of the metal component began to flake away, more surface area is exposed and the rusting continues until all the material’s oxygen, water, and carbon dioxide are expended, or the material is dissolved entirely. In the case of fasteners, such as bolts and screws, rust corrosion can lead to a larger component or entire machine failing, making it all the more important to address rust problems promptly.
Removing a Rusted Fastener
If bolts and screws are exposed to moisture for a protracted length of time, they will begin to rust very quickly. Fasteners in automobile components, ships, and even home appliances used outdoors are subject to high levels of moisture that can degrade the function of the devices in which the fasteners are housed. Removing these parts can be difficult, especially if the threads have become rusted or rust has degraded the metal head, making them hard to grip with a wrench or screwdriver. There are several options for helping to remove rusted fasteners, including:
- Lubrication: Commercial and industrial lubricants can often reach a fastener’s threads, which may be difficult for tools to grasp. Applying lubricant to the bolt, then tapping its head with a hammer, can help the lubricant penetrate the fitting and loosen the bolt sufficiently to be removed.
- Cutting: If a fastener has rusted too severely to be salvaged, cutting it out may be the only alternative, even though it will render the fastener unusable. A cut-off wheel, nut-splitter, or even industrial shears can be used to permanently extricate a rusted fastener. Similarly, clamping a bolt with a vise-grip and twisting its head off can also free it from its slot.
- Torching: Using a moderate to low heat torch is another viable method for removing a rusted bolt. Applying adequate heat may allow the nut or the bolt to expand enough to be loosened. However, care must be taken when relying on torch removal, as some lubricants are flammable and lubricant-treated fasteners may ignite if exposed to a flame.
Rust Removal Methods
While many people simply remove and replace rusted fasteners, in some cases, older or product-specific fasteners cannot be substituted with replacements. Restoring bolts and screws, via rust removal, cleaning, and reinstallation, can be a vital and cost-efficient way of keeping a device functional. There are numerous ways to remove rust, each with its own degree of effectiveness. Some of the more common techniques include:
- Sanding: After removing a rusted fastener, rubbing it with a fine grade sandpaper or steel wool is a straightforward way to scrap off the accumulated rust. This is a relatively simple and inexpensive method, but can be time-consuming and often requires a lubricant to make the fastener reusable.
- Hydrogen Peroxide: Hydrogen peroxide can be applied to fasteners and left to stand while it dissolves some of the surface rust. After the fastener has been removed, it typically needs to be scoured with a hard brush in order to clean the threads and the shank. Hydrogen peroxide is also a relatively inexpensive method, but it may leave residual spots of rust behind.
- Repainting: Coatings can be used to limit the spread of rust. After removing rust from a particular area of a metal component, painting over that surface can help to shield the metal from environmental effects, such as moisture, that lead to rust. Likewise, an oily or wax-based coating can have similar effects.
- Rust Cleaner: There are a variety of different rust cleaner brands available from numerous manufacturers. Most of them include a dissolving agent, such as oxalic acid, that chemically reacts with iron oxide to break it away from the base material. These rust cleaners are particularly useful for small metal parts, such as fasteners, which can be dipped, soaked, or sprayed in the solution to remove rust. As always, the manufacturer’s safety recommendations should be closely consulted, as some of these cleaners may be harmful if misused.
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