Abstract: A mandrel is provided for insertion in a well pipestring. First and second semi-cylindrical sections, in turn, are arranged to be brought together from opposite sides of the mandrel to surround the mandrel in coaxial relationship. Each of these semi-cylindrical sections has holes supporting wire brushes, the brushes being held secure when the semi-cylindrical sections are fitted about the mandrel. End ring members are received over the opposite ends of the mandrel to engage about the ends of the semi-cylindrical sections and hold them securely together. Appropriate collar members threaded on the ends of the mandrel in turn will hold the ring members axially in place and also serve to connect the mandrel to the pipe string. The mandrel itself has a central bore sufficient to maintain the normal circulation or reverse circulation during a brushing operation and the semi-cylindrical sections holding the brushes can be easily removed and replaced as required.