I work as a brewer and while I'm not certain that wearing long sleeves is disallowed, it generally isn't done for safety reasons. You can't have shirt sleeves caught in motors or mills or conveyors and the like, not to mention the heat of the brewhouse in the summer, so basically if it can't be covered by a t-shirt it will be on display. Plenty of people I work with have visible tattoos and it isn't an issue at all in day to day work. I don't know what they would mean in terms of promotion to management but there is so little upward mobility in the company that I'm not sure it matters that much.
They have hired people with hand and neck tattoos to work the bottling line before so there's always that ad an option if you have job stoppers. Wouldn't want to work that job though.