Every now and again, we get questions on structural bolt reuse, and the answer is always the same: maybe. When we talk about reusing a bolt, we’re referring to when a pretensioned bolt is loosened and then re-pretensioned. Here, we’ll discuss whether or not a bolt can be reused according to RCSC standards. Note that this blog is for informational purposes only. You should always defer to the RCSC standards and your engineer.
Previously Pretensioned Structural Bolt Reuse
Sometimes, you may need to remove a pretensioned bolt and then need to reinstall it. Depending on the type of bolt, and the express permission from your engineer, you may be able to reinstall it. RCSC Section 2.3.3 allows uncoated F3125 Grade A325 bolts to be reused with the engineer’s permission. Galvanized bolts and F3125 Grade A490 bolts that have been pretensioned may not be reused at all.
Snugged Bolt Reuse
Snugging a bolt refers to tightening a bolt with a few impacts of an impact wrench or with the full effort of a worker using an ordinary wrench. F3125 Grade A325 bolts that are snugged can usually be reused. Snugged F3125 Grade A490 bolts and galvanized Grade A325 bolts can only be considered for reuse if snugged by hand or very lightly snugged with an impact wrench.
Determining the Possibility of Pretensioned or Snugged Bolt Reuse
So, your bolt meets the above qualification, but can you actually reuse it? Reuse of a structural bolt is permitted only when a bolt has not been stressed past its yield point. A quick way of telling if a F3125 Grade A325 bolt has yielded is to attempt to screw a nut onto the bolt. If the nut does not fasten onto the entirety of the bolt’s threads, the bolt has been stressed beyond its yield point. This is because the bolt has stretched, and the threads are farther apart than they should be. Note that because of overtapping of nut threads for galvanized bolting assemblies, you cannot use this method for galvanized bolts.
Though there are ways to check whether a bolt can be reused after pretensioning or snugging, Birmingham Fastener strongly recommends discussing bolt reuse with the engineer on your project.