fixedly attached and made integral with the bodies of the couplers by welding the blades 12 to the coupler body machining the blades 12 and body or casting the blades 12 and body all as a single unit as shown if fig3 although the preferred embodiment has ribs that helical other embodiments may be made with spiral ribs diagonal ribs straight ribs or other configurations for example fig3 shows an embodiment 65 that has straight ribs 66 typically an ordinary coupler is attached to the casing string using a wrench to hold it while the threads are engaged because the centralizer couplers have the helical ribs running almost the entire length of the coupling an ordinary wrench cannot be used to make up the connection as such there is no way to install or remove one of these centralizers in the field in the present embodiment however a wrench adapter is used to attach and remove the centralizers fig4 and 6 show the wrench adapter 120 it has a cylindrical body that is made of two halves the two halves are brought together and hinges 125 are installed on one side in this way the adapter can be opened and closed two handles 127 are provided to allow a user install remove the adapter a latching mechanism 130 discussed below is used to lock the adapter in the closed position fig4 also shows an inside wall 132 b of the wrench adapter the opposite inside wall has a similar.