The answer is when it is pure art. I noticed this on the side of a building in South Austin. I really liked the colors and took the picture. I looked further and found that what appeared to be a functioning valve was not connected to anything and had not been for a long time. But, it makes for a nice “arty” decoration.
I almost wrote that this is not functioning, but that would have been incorrect as it is functioning as art.
Passing Through . . . . 
Fantastic! We’ve seen less interesting “art” in actual galleries for thousand of $$$!
Love it!
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