Found some 1960s blueprints for the old municipal building downtown in a damp box. They had a 4-inch brass tube line running from the tax office straight to the basment incinerator. Why would they need to burn documents that fast. My landlord says I cant install a replica in our hallway but he is a coward. Anyone know where to get cheap 4 inch gaskets nowadays. The ones online cost an arm and a leg.