Apparatus for use in maintaining a well pipe centered within a well bore

A centralizer for maintaining a well pipe centered within a well bore, comprising upper and lower sleeves adapted to be disposed about the pipe in axially spaced relation, a plurality of springs having bowed portions intermediate their opposite ends, and each sleeve having an outwardly bent, circumferential portion and windows formed in such portion, the opposite ends of the springs having outwardly bent portions which are received within the windows, arcuate rods fitting within the outwardly bent portions of the springs and sleeves, and means on the sleeves for limiting endwise as well as radial movement of the rods away from the protruding portions of said springs within said windows, whereby the ends of the springs are connected to the sleeves with their bowed portions arranged to yieldably engage the well bore at circumferentially spaced locations about the well bore.

Apparatus for use in maintaining a well pipe centered within a well bore, comprising a centralizer having upper and lower sleeves adapted to be disposed about the pipe and springs having opposite ends connected to the sleeves and outwardly bowed portions intermediate such ends adapted to yieldably engage the well bore at circumferentially spaced locations thereabout, and at least one stop collar adapted to be fixedly mounted on the pipe in a location which limits endwise movement of the centralizer as a whole while permitting the sleeves to move relatively toward and away from one another as the springs expand and contract, each such collar comprising a circumferentially split sleeve having means to draw its free edges together in order to draw it about the pipe, and shoes carried by the sleeve at substantially equally, circumferentially spaced locations, each shoe including a pin mounted within a hole in the sleeve, and a cup on the inner end of the pin having a concave inner surface whose periphery engages the pipe, the inner circumference of the sleeve of the collar having a substantially conically shaped, concave surface engageable with a similarly shaped surface on the outer side of the cup to wedge the cup inwardly against the pipe as the collar sleeve is drawn about the pipe.

A stop collar adapted to be clamped about a well pipe within a well bore in order to limit endwise movement of a centralizer or like tool disposed about said pipe, said collar comprising a circumferentially split sleeve having means to draw its opposite edges together in order to draw it about the pipe, and shoes carried by the sleeve at substantially equally, circumferentially spaced locations, each shoe including a pin mounted within a hole in the sleeve, and a cup on the inner end of the pin having a concave inner surface whose periphery engages the pipe, the inner circumference of the sleeve having a substantially conical, concave surface engageable with a similarly shaped surface on the outer side of the cup to wedge the cup inwardly against the pipe as the sleeve is drawn about the pipe.