Expandable centralizer for expandable pipe string

摘要

An expandable bow spring centralizer (8) having a first collar (10A) coupled to and spaced apart from a second collar (10B) through a plurality of bow springs (30) wherein a fin (32) is connected to each bow spring (30), and then connected to one or more adjacent fins (32) upon collapse of the bow springs (30) to form a restraining band (39) that may be ruptured, e.g., upon expansion of the expandable pipe string (80).