Centralizers for centralizing well casings

A centralizer for centralizing a pipe down hole comprising:

• a band forming a hoop for circumferentially surrounding and affixing to the pipe, said hoop having a central conduit defining a longitudinal axis;
• a plurality of arcuate cuffs having first and second ends, said cuffs affixed to said band and positioned circumferentially around said band, said cuffs being flexible so as to be positionable in a first condition wherein said cuffs are retracted radially inward so as to be substantially flat against said band and said cuffs positionable in a second condition wherein each of said cuffs are expanded radially outward to form a loop wherein said loop has a central axis parallel to said band's longitudinal axis, each of said cuffs storing mechanical spring energy when positioned in said first radially retracted condition with said mechanical spring energy attempting to force said cuffs into said second radially expanded condition;
• a lock selectively locking said arcuate cuffs into said first condition;
• and
• an actuator for selectively unlocking said lock to cause said cuffs to expand radially from said first condition to said second condition due to the mechanical spring energy stored within said cuffs.