I’m working on a project where we would like to install thru-bolts through a slab. We need the bolts to be flush with the surrounding plate on the top of slab, however Hilti does not make countersunk bolts larger than 3/8” diameter. Therefore, we would like to plug weld a ¾” anchor rod directly to the surrounding steel plate, and grind the weld flush with the steel plate (see the attached sketch). We are looking at two anchor rod options: HAS-E and HAS Super, Grade B7. I have two questions:
- Can both of the anchor rod options be welded to the steel plate?
- Are there any special considerations when welding either of the anchor rod options to the steel plate?
Curtis,
From a feasibility standpoint, there is no reason why a HAS threaded rod cannot be welded to a steel plate by a skilled welder; however, there is no test data or experiential data from Hilti available for reference as this is not typical. A few issues to consider are:
- the heat generated by the welding may cause unpredictable changes in the composition of the steel anchor body
- due to the intense heat generated during the welding process, heat transfer could affect the adhesive matrix and cause either debonding or carbonizing of the adhesive itself (important to mention, but I am assuming from your sketch no adhesive is involved)
- the possible removal of corrosion resistant coating from the threaded rod itself
- possible removal of the length identification mark
- the extent to which the above would occur is dependent on the duration of the weld and the size of anchor, but this is not quantifiable
Onsite evaluation by a third party testing agency is always an option.
Thank you for your question!