A fluid flow processing plant for pig-free removal of wax and hydrate deposits in hydrocarbon production flowlines may include at least one cooling flowline. Further, the fluid flow processing plant my include cooling means arranged to cool the fluid in the at least one cooling flowline over a cooling section until the fluid reaches a temperature at or near the cooling flowline's surrounding temperature (Tsea) and at least one vehicle arranged on or near the outer circumference of the cooling flowline. Furthermore, each vehicle may include at least one sleeve configured to at least partly surround an outer circumference of the cooling flowline, deposit removing means being configured to remove deposits situated on an inner wall of the cooling flowline, and a propulsion unit configured to drive the vehicle bi-directionally on the cooling flowline.