Junctions of metal for pipes; expansion joints of metal for floors and walls, piping and ducting; couplings of metal for tubing; structural metal joint connectors for pipes; metal couplings for fire hoses; fittings of metal for pipes; metal hose fittings; pipe unions of metal, namely, metal joinery fittings; rotating junctions of metal for pipes; pipe fittings of metal; junctions of metal for pipes including those from alloy steel and titanium