Method for reducing loss of flow due to hydrate solids deposits and wax deposition in a pipeline without the aid of chemicals and system for transporting a flow of wellstream hydrocarbons containing water, using a main pipeline and a cold-flow reactor connected to the main pipeline or within or forming a part of the pipeline, wherein at least a portion of the wellstream is fed to the cold-flow reactor. Also provided is a method for preventing hydrate nucleation and growth in a pipeline and preventing hydrate agglomeration as well as for preventing wax deposition. The provided method eliminates the use of energized equipment for melting, grinding or scraping hydrate solids from inside of pipelines or flowlines. Generating dry hydrates to be mixed with main flow of a wellstream is also described.