I painted mine with Rustoleum. I had sandstone lintels so "Almond" was a good color match.

I do think it's a good idea to clean them up and seal them. Paint is a protective film, an agent to preserve. Lots of times we hyper-focus on the aesthetics of paint and often lose sight of its purpose/function.

We call these lintels. You probably don't need a grinder. A stiff putty knife and some sandpaper should clean them up good enough to be painted. Rustoleum is okay, but eventually the rust will come back. There are better primers out there designed for rust, but they are not cheap...probably not worth it because the rust may still come back even when using the best primers.

I think it is wrong to assume that you need to remove the rust and protect the steel. Given that it was not painted from the start, it is likely that it is a type of steel that is formulated to form a stable "patina" that is relatively impervious. The fact that it has a nice patina rather than producing large flakes and pits indicates that it is that type of steel. Painting it might actually cause it to deteriorate at an unacceptable rate. Do not rush into remedying a problem that does not exist. Either leave it be or investigate before you jump in.

thanks for the info guys. I am kinda leaning towards not painting it. I was curious how this is not leaving rust stains on the brick or concrete below it - that makes me think painting is not neccessary. I have always painted them on my other houses, but of course they were already painted before I got there. I just didnt want it to rust so badly that it weakens and then all the mortar starts to crack apart. I guess the lintels are only meant to hold up the brick while the mortar is curing? Thanks again guys

I am not saying don't paint them, but I think you should check with someone that knows something. Unfortunately, that would not be me :-( Another forum might be your best bet. "Home Repairs" has some people that check in that might know something about Metallurgy.

I think that it does support the bricks above it. Temporary support can be provided by other means and removed after the mortar cures. (A couple of 2x4s wedged by a couple more would work on the entry door.) Given that it is 21 years old and has a nice patina, you can probably take your time to figure it out. There is no sense in rushing in and possibly screwing something up. A couple more months is not going to make that much difference. It was probably already oxidized and relatively stable when it was installed and that is why it did not stain anything.

There are ways to passivate some steel alloys that you might find more attractive than oxide. Nitric and phosphoric acid treatments are common, I think. I really have no idea if this is possible with your type of beam or post-installation.

I think that I started looking into this kind of chemistry when I first checked into modern automotive coolants. Stuff was pretty simple when engines were all iron and radiators were copper with lead solder. One coolant fit all. Now that aluminum plastic and steel have been thrown into the mix, and silicate as a passivation agent is out due to the need to replace coolant every two years, there are a lot of different coolants and you best use the best coolant specified by your manufacturer unless you have an inorganic chemistry-related degree.