Aluminum (6063T6) Grating Sitting on HDG Steel in Humid Environment

[JoelTXCive]

We have an existing storm water lift station with a steel platform + grating at the bottom (+/-20ft below grade).

This is Houston, so it's hot and humid all the time; and especially hot & humid at the bottom of a dark wet well with flowing water in it.

Currently the HDG grating panels are too heavy to be easily removed for access to a sump pump so the operator would like us to come up with a better setup.

We are looking at replacing five rectangular steel grating panels with aluminum ones. (Approx. 2ft by 4ft grating panels). As of now, there will be no connectors. The panels will just rest on the HDG beams.

I am concerned about galvanic reaction between the dissimilar metals; and what I can do to isolate them.

Questions:

1) Should I be concerned about this; or not worry about?

2) Is there a paint/coating product that could be applied to the top of the existing beams? Or a very thin neoprene type pad that could be glued to the beam flanges?

Thank you in advance for comments.

 

[TugboatEng]

Gratings tend to chip any coatings underneath them. I use adhesive backed silicone tape to protect the coating. Neoprene would also work and is less expensive.

Also consider the use of fiberglass gratings if height allows.

 

[JoelTXCive]

Thank you TugboatEng.

I looked at FRP & fiberglass gratings, but unfortunately, they do not have the load values that I need for my span (about 4ft).

I'll look at the silicone backed tape you suggested.

I think you bring up a valid point on the coatings being chipped, but that might be a risk I have to run. I have a general concern about any tapes/adhesives falling off due to the environment.

See below photo. All of the chopped-up/askew steel grating is what we are looking at replacing with aluminum. (the beams underneath also have to be replaced/modified).

Under a low flow situation, there is a small continuous stream of water entering the wet well, but in a rain event, the whole 20ft deep well will fill up water.

 

[TugboatEng]

Tape works fine for me. Treat the surface as if you're going to apply any coating, do some surface prep.

Sorry for bad lighting: