Centraliser including a collar with a groove for limiting longitudinal movement

摘要

A bow spring centraliser 110 is adapted for concentric mounting on a sub 112. The centraliser consists of collars 124, 126 with internal grooves 118. These grooves co-operate with shoulders 162 on the sub to limit longitudinal movement. The collar also includes a portion of reduced outside diameter 154 for receiving the end of bow springs 120. An alternative bow spring centraliser is disclosed featuring outwardly extending vanes on a sub, whereby the bow springs move between a first bowed position standing off the sub to a second flat position between the vanes. Another alternative bow spring centraliser is disclosed having a pair of collars with co-operating shoulders on a sub.