Kevod harav, do glass tables need hagala?
Whether glass can be koshered is a subject of debate among the Rishonim and Poskim. Many hold that glass never needs hagala, while others hold it needs hagala for pesach, and still others hold glass can not be koshered. Ashkenazim generally rule like the Rama for pesach, that glass can not be koshered. The rest of the year one can do hagala to glass. Sfardim rule like the Shulchan Aruch that glass never needs to be koshered at all.
n.b. A table usually does not get food on it directly from a fire, and if you need to kosher it, pouring hot water from a pot would be enough.