Multi-stage apparatus for installing tubular goods

Abstract

A pipe gripping assembly includes, among other components, a fluid conducting swivel, a fluid-powered linear actuator and a pipe gripping assembly. The linear actuator has a central rod mounted within a multi-stage, segmented barrel assembly. Each barrel segment acts as a piston, with control fluid forces being transmitted to the barrel assembly to selectively extend or retract the barrel assembly in order to engage or disengage the pipe gripping assembly. By aggregating such force, the total combined force generated by the barrel piston assemblies, the actuator assembly of the present invention can operate using pneumatic control fluid, and can operate at much lower control fluid pressures than other actuators.

What is claimed: 
     
         1 . An apparatus for installing pipe in a wellbore comprising:
 a) a linear actuator comprising:
 i) a central tubular member; 
 ii) a barrel assembly disposed around said central tubular member and having an adjustable length; and 
   b) a pipe gripping apparatus adapted to frictionally grip a section of pipe;   c) at least one linkage member connecting said barrel assembly to said pipe gripping apparatus.   
     
     
         2 . The apparatus of  claim 1 , wherein said linear actuator further comprises an annular space between an outer surface of said central tubular member and an inner surface of said barrel assembly. 
     
     
         3 . The apparatus of  claim 2 , further comprising at least one barrel piston member moveably disposed within said annular space. 
     
     
         4 . The apparatus of  claim 3 , wherein said at least one barrel piston assembly is connected to said barrel assembly, and axial movement of said at least one barrel piston causes the length of said barrel assembly to change. 
     
     
         5 . The apparatus of  claim 1 , wherein said linear actuator is pneumatically operated. 
     
     
         6 . A linear actuator comprising:
 a) a central tubular member having a through bore and an outer surface;   b) at least one barrel segment having an inner surface, wherein said at least one barrel segment is disposed around said central tubular member to define an annular space between said outer surface of said tubular member and said inner surface of said barrel segment;   c) a plurality of divider members affixed to said outer surface of said central tubular member within said annular space; and   d) at least one piston member attached to said at least one barrel segment, and movably disposed within said annular space between said divider members.   
     
     
         7 . The apparatus of  claim 6 , wherein axial movement of said at least one piston member causes said at least one barrel segment to move axially relative to said central tubular member. 
     
     
         8 . The apparatus of  claim 6 , further comprising at least one elastomeric seal member between each of said divider members and said at least one barrel segment. 
     
     
         9 . The apparatus of  claim 6 , further comprising at least one elastomeric seal member between said at least one piston member and said outer surface of said central tubular member. 
     
     
         10 . The apparatus of  claim 6 , further comprising a plurality of tubular tie rods disposed within said annular space and oriented substantially parallel to said central rod. 
     
     
         11 . The apparatus of  claim 10 , wherein each of said tie rods have a central through bore and a plurality of transverse bores extending from said central through bore into said annular space. 
     
     
         12 . The apparatus of  claim 10 , wherein said at least one piston member has a plurality of through bores oriented substantially parallel to the longitudinal axis of said central tubular member, and said tie rods are moveably received within said through bores. 
     
     
         13 . The apparatus of  claim 12 , further comprising:
 a) at least one elastomeric seal member between said divider members and said at least one barrel segment;   b) at least one elastomeric seal member between said at least one piston member and said outer surface of said central tubular member; and   c) at least one elastomeric seal member between said at least one piston member and said tie rods.   
     
     
         14 . The apparatus of  claim 6 , wherein said linear actuator is pneumatically operated. 
     
     
         15 . A linear actuator comprising:
 a) a central tubular member having a through bore and an outer surface;   b) a barrel cap member fixedly attached to said central tubular member;   c) a barrel base member having a central bore, wherein said tubular member is movably received within said central bore;   d) at least one substantially cylindrical barrel segment attached to said barrel base member and having an inner surface, wherein said at least one barrel segment is disposed around said central tubular member to define an annular space between said outer surface of said tubular member and said inner surface of said barrel segment;   e) a plurality of divider members fixedly attached to said central tubular member within said annular space, wherein said divider members extend substantially from said outer surface of said central tubular member to said inner surface of said at least one barrel segment; and   f) at least one piston member attached to said at least one barrel segment, and movably disposed within said annular space between said divider members.   
     
     
         16 . The apparatus of  claim 15 , wherein axial movement of said at least one piston member causes said barrel base member and said at least one barrel segment to move axially relative to said central tubular member. 
     
     
         17 . The apparatus of  claim 15 , further comprising at least one elastomeric seal member between each of said divider members and said at least one barrel segment. 
     
     
         18 . The apparatus of  claim 15 , further comprising:
 a) at least one elastomeric seal member between said at least one piston member and said outer surface of said central tubular member; and   b) at least one elastomeric seal member between said barrel base member and said outer surface of said central tubular member.   
     
     
         19 . The apparatus of  claim 15 , further comprising a plurality of tubular tie rods disposed within said annular space and oriented substantially parallel to said central rod. 
     
     
         20 . The apparatus of  claim 19 , wherein each of said tie rods have a central through bore and a plurality of transverse bores extending from said central through bore into said annular space.