Expansion anchors torque into concrete 1

[Gokhan G]

Hi everyone,

I have been inspecting previously installed expansion anchors using a torque wrench. According to Dewalt specifications, the installation torque should be 25 ft-lbs. In the guidelines, it is mentioned that anchors experience a relaxation of preload immediately after tightening due to creep within the concrete or masonry. The torque value measured after installation is typically 50% of that initially applied to set the anchor.

I have a question regarding the verification of the torque after installation. Should I verify the ultimate torque read after installation, for example, a week later? Or should I verify the initial torque that was applied?

For instance, if the anchors were initially torqued to 50 ft-lbs, and I read in torque wrench 25 ft-lbs when I inspect them, is this the correct verification? Or if the anchors were set at 25 ft-lbs initially, but when I inspect them, I read 12-15 ft-lbs, which case is the correct verification?

Thank you in advance for your assistance!

 

[EngDM]

I would contact Dewalt for more information. They should be able to give you a detailed answer from the manufacturer/supplier that you could fall back on in the event anything ever gets challenged.

 

[Gokhan G]

I asked them however was not clear to me. Installation torque was specified 25 ft-lbs.

And they told “installers should set specified value when they install anchors. “ and expect 50% relaxation later. (Next
Day or more) But i m not sure if i have to read specified value in torque wrench or %50 of installation torque.

Anybody has experience about this, response highly appreciate. Thank you

 

[Heaviside1925]

OP,
I don't think you have a way of knowing if the anchors were originally installed using the installation torque. Based on what Dewalt has told you the torque should be anywhere between 100%-50% post installation but since the anchors are expected to relax, there is no way of determining if they were installed to the required torque in the first place.
I am not sure of Dewalt is currently understanding your question.
Maybe the question should be "If inspecting the bolts at a later time with a torque wrench, is there a minimum torque value to ensure the anchors are properly set."
If the answer is no, then,
If the installation toque is required for proper anchor setting/expansion, you could ask Dewalt if the bolts can be re-torqued to the installation torque because that would be the only way I could see of actually verifying this.

 

[JLNJ]

If there is an ESR on the fasteners, it might have the installation details you are looking for.

 

[Gokhan G]

Thank you all. I appreciate all answers!