What color would you paint it?

[shaygetz]

The refineries around Baton Rouge are a combination of white or silver, primarily based on age/phases of the units. Both colors reflect heat and for that reason those should be used. BR is right about color coding the smaller pipes but you'll have to dig deeper for the why and how. Weathering should be kept to a fair minimum, these places are continually under renovation and inspection and wouldn't be allowed to get too crusty looking.