![]() In projects such as water treatment plants, factories, or even wineries, where adhesive anchors will be exposed to chemicals, the same factors need to be considered. Some manufacturers have done extensive testing with these preservative chemicals on the anchors and may have specific recommendations. Depending on the level of preservative used on the wood, zinc or mechanically galvanized anchors are most appropriate. This scenario often requires anchors in the medium corrosion-resistance class. Simpson Strong-Tie In many applications, screw anchors are effective and efficient.Īnother common potentially corrosive environment occurs when anchors are used to attach preservative-treated (often called “pressure treated”) wood sill plates to concrete. Prevent exposure to and pooling of water (which acts as the electrolyte).The smaller/thinner item is often the plate or fixture being attached. This is because the smaller/thinner items will usually corrode first. Ensure that the anchor is the anode when dissimilar metals are present.Separate electrochemically dissimilar metals with insulating materials.Use anchors and metals with similar electrochemical potential.Good detailing practices can help reduce the galvanic corrosion potential of anchors. The significant corrosion often visible in marine environments, for example, is due to the highly corrosive reaction caused by the salt in sea water. Corrosion also increases with increasing conductivity of the electrolyte, such as salt water. The farther apart the metals are on the table, the greater the difference in electrochemical potential and the more rapidly corrosion will occur. Table 2 shows the galvanic potential of different metals. This is called a “galvanic couple,” with the more anodic metal corroding. Galvanic corrosion occurs when two electrochemically dissimilar materials contact each other in the presence of an electrolyte (in this case, water) that acts as a conductive path for metal ions to move from anodic to cathodic metals. Generally speaking, the potential for corrosion is heavily influenced by the galvanic activity that is likely to occur. Temporary anchors (those in corrosive conditions for less than six months) fall into the low corrosion-resistance classification since they typically don’t have substantial time to corrode. The rating on Table 1 corresponds to the type of steel or steel coating required on the anchor. Other exposures ranging from dry exterior to wet service to elevated service will be classified as medium to high to severe, respectively. Interior exposure only (dry service) falls into the low corrosion-resistance classification shown in Table 1, while an application in an unprotected ocean-front location falls under the severe classification. First, the in-service exposure conditions determine the necessary corrosion resistance of the anchor. The environment where the anchor is to be used will often dictate your anchor choice. Jobsite obstacles that may hamper proper anchor installation ![]() Substrates (what is the anchor being installed into)Ħ. When choosing a post-installed anchor, start by considering these six main factors:1.Ğnvironmental conditionsģ. In this article, we’ll walk you through the process of selecting an anchor so you can be better equipped on future projects where post-installed anchors are needed or even just favored in lieu of cast-in-place anchors. There are actually several factors that affect proper anchor choice, so considering them all is essential. It’s so difficult, in fact, that post-installed anchors are now becoming the preferred method for attaching wood, steel, and cold-formed steel components to concrete instead of cast-in-place anchors.Īlthough post-installed anchors are commonly used in concrete construction, choosing the right anchor for a given application is not as simple as it might appear. ![]() Setting a cast-in-place anchor in just the right location can be a daunting task.
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