Stainless Steel Refinishing - On Construction Site 1

[hondashadow1100vt]

I have 10 +/- 316L stainless steel product storage tanks all of which are on the order of 10,000 to 20,000 gallons in size. The tanks were furnished with the specified mill finish, pickled and passivated to an approximate No. 1 matte finish appearance. My project is subject to the approval/disapproval of a powerful arts commission which is requesting a mirror finish to the exterior of the tanks. In this instance their demands will need to be satisfied. What means and methods are available to achieving this (e.g., grinding, blasting, cladding, coating, etc.)? Any insights and feedback would be greatly appreciated. Thank you in advance!

 

[EdStainless]

It will take sequential grinding, with smoother and smoother grits each pass.
It is better to do wet. And orbital might be better than straight belts so that you don't develop a pattern.
Start with a grit that will produce a finish about the same roughness that you have now, then work to finer one, and so on.
The final polish is critical, it can't just be a buff. That would smear metal, look shiny, and rust like crazy.
People usually work to 1200 grit or so, then go to cloth pads and ceramic slurry for finer polish.

1. They do know that there will be a lot of reflected light, I hope that there are not roads or buildings within half a mile of these.
2. These tanks will get very hot in the sun.
3. You might never achieve a mirror finish, depending on the steel itself, especially at welds.

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P.E. Metallurgy, Plymouth Tube

 

[AWloo]

Out of curiosity what is the purpose of the mirror finish? Aesthetics?

 

[MagBen]

Ed, any specific reason why recommended wet? we have couple of regular Stainless steel grades for which only dry grinidng is allowed, no wet.

 

[hondashadow1100vt]

Thanks responders!

EdStainless:
1. There are major bridges and highways adjacent to two of the sites. Would the requested mirror finish incur a safety hazard? Is there any documented incident of a mirror surface resulting in a hazard?
2. I would expect the tanks to get hot in the sun regardless. Heating the product too much (e.g., > 130-deg F) would be a concern.
3. Understood. The mirror finish seems like something asymptotically approached ...at best.

AWloo: Apart from aesthetics, there is no actual purpose to the mirror finish. This project is publically funded and is therefore subject to this commissions approval. The commission approves renderings during the design phase. After construction completion they compare the renderings to completed construction photos and then ask for corrective action where the photos do not match the renderings. This is all in the name of architectural beatification of the town (which I support within practical reason).

 

[CoryPad]

Look for information regarding the building at 20 Fenchurch Street in London, England, UK. The building shape and reflectivity resulted in damage to parked cars nearby.

 

[djhurayt]

There was an episode of the 80s era show CHIPS were a mirror was responsible for a large interstate traffic incident. ha ha

 

[racookpe1978]

Yes. The flash from these surfaces - multiple tanks, different diameters, different heights and different positions on the hillside near the highway and, most important: each one nicely round! - means that there are no "safe" days of the year or times of day where you can assure that drivers will not be blinded by the mirror finish.

 

[hokie66]

Sounds like the Arts Commission needs to talk to the State highway authority. Otherwise, the Arts Commission may find itself in a pickle.

 

[EdStainless]

I have seen a site where a SS roof had to be pickled to dull it because of traffic dangers.
I can connect you with someone who specializes is architectural use of stainless, she knows of many cases where there were problems.
The polished surface will get hotter than the dull one, too hot to touch for sure (over 130F) if you have full sun.

I suggest wet because it is easier to avoid embedding abrasive (and grind debris) when you wet grind, and you get finer finishes.

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P.E. Metallurgy, Plymouth Tube

 

[berkshire]

hondashadow1100vt (Civil/Environmental)
If this group is bound and determined to do this, it might be more cost effective to clad the tanks with Mirror finish stainless steel than take the time to grind and polish mill finish to number 10. The labor hours alone may more than cover the cost of 18 or 20 gage cladding.
B.E.

You are judged not by what you know, but by what you can do.

 

[mrfailure]

You might want to look at the processes used on the Chicago Bean sculpture for some tips. This link may help:

http://www.thefabricator.com/article/arcwelding/metal-fabricating-in-a-new-millennium