Seems to me that hot dip galvanizing is going to make all your marks go away anyway.  Any buffing done then will be the true finish product.  You wouldn't want any major grinder marks, but it really should not be that critical to spend too much time making it look like an automobile finish.  Does this finish code give you application examples? And does this finish have to be accomplished before galvanizing?  I can see smoothing things after the hot dip because that is going to be a rough finish with some very sharp areas.

Have a Great Day,  Brent

   I used the edge of a flap disk on a 4 1/2" angle grinder to blend the welds on ralings I built, it worked well, but does take some time. The nicer You weld, the less You will grind.

    A really small air powered belt grinder ["Dynafile"]  might help too.

    I too think hot dip galvanizing will hide minor grinding marks, and that some finishing will be needed after. I think "buffed" with a buffing wheel & compound would be a waste of time, I am not familliar with the finish spec You mentioned.

I'm not sure about the hot dip galvanizing. When I do mine most are powder coated/painted and this last job was Gloss black which is a whole different ball game. I just used the grinder with a stone to nock off the high spots to where its almost flush then swap out the stone for the 120 grit sanding wheel. It takes it out pretty quick and leaves a nice smooth finish. The powder coat don't like grinder scratches either, so I've been told by the powder coater. But then again, I'm in Tn.

Dennis,
Have you or can you provide them with a sample to see what they will accept?
You may not have to blend as much as you think after galv.

I usually start with a hard disc on a 4 1/2" grinder, then use a rotary file and or a stone on an end grinder. After the meat is gone I use a flapper wheel on the side grinder and also on the end grinder. This is very time consuming and the consumables cost will be high.

Some jobs we do require a lot of blending others not so much.

I have never used the flex finger grinder.

I agree that the galv. will hide a lot of minor scratches but not sure about shop buffing after hot dip galv. Seems that the galv. should be undisturbed.

If time allows you to, I would send a sample to the proper authority (sometimes the GC will expect more than the owner or arch.)  

Good luck with it.

dschlotz,    First all joints of 1 1/2 "grind with 4 1/2 "grinder with a flap disc 60 grit then finish with a DA sander 100 grit, as far as the pickets at 3" take extra care when welding so you don't have allot of clean up. After welding use a bandfile with 80 or 90 grit to hit any lumps or other imperfections. ( one thing I have found is instruct whoever welds this product is responsible for finish cleaning.) Use all internal holes for venting and after galv. bring back to shop for inspection , need to remove sharp burrs,icicles,etc.and then touchup with a good galv. repair spray. ( Remember a Nightmare of railing job,stadium full of rail shipped direct to jobsite after galv. ,installed under rush deadline so Justine Timberlake concert could take place ,next week hundreds of complaints about cuts and punctures from concert goers.) Wouldn't been funny if it was my company that was invovled, "sometimes the best jobs are the ones you don't get"       PS GO STEELERS AND PENS

When you say 'flex finger" are you talking about the little belt sanders built on a 4 1/2" grinder?

I've seen those work pretty slick on blending small pipe handrail welds. Buy lot's and lot's of belts tho : )
It's a tedious task, that's for sure. Plug in plenty of labor for that type of finnish work. My opinion.

If the flex finger is something different, then direct me to it because I'd be interested in seeing what it is.

JTMcC.

Yeah, agree 100% about the labor for finish grinding. The small job I did at this clients house was around 12-14ft total, two sections. I can't tell you how much time I spent grinding, smoothing on that one. Best thing is when you put in your balisters is to make sure you have the "perfect" weld, no boogers, blobs etc. On this last job the balisters tucked up underneath the toprail in a piece of 1.5" channel, that saved grinding time because you could'nt reach it by wrapping your hand around it and you could'nt see it unless you fell over and happened to look up. Those small sections I did on my other post took around 5 hours each, start to finish.