Interlock system for tubular running tools

Abstract

An interlock system for use with casing running tools including, without limitation, casing running tools utilized with rig top drive systems. A pressure circuit is in communication with casing running tool slips and spider assembly slips. The pressure circuit controls the supply of pressure to: (1) release the spider slips only when the casing running tool slips are engaged and supporting the entire pipe string; and (2) release the casing running tool slips only when the spider slips are engaged and supporting the entire pipe string.

What is claimed: 
     
         1 . An apparatus for controlling the gripping and releasing of tubular members comprising:
 a) a casing running tool having slips for optionally gripping and releasing a first tubular member;   b) a spider having slips for optionally gripping and releasing a second tubular member; and   c) a pressure circuit in communication with said casing running tool slips and said spider slips, wherein said pressure circuit controls the supply of pressure to release said spider slips only when said casing running tool slips are engaged against said first tubular member, and said first and second tubular members are connected to each other.   
     
     
         2 . The apparatus of  claim 1 , wherein said pressure circuit controls the supply of pressure to release said casing running tool slips only when said spider slips are engaged against a tubular. 
     
     
         3 . The apparatus of  claim 1 , further comprising:
 a) a processor for controlling operation of said pressure circuit;   b) a tension load cell, connected to said processor, for measuring tensile loading near said casing running tool; and   c) a compression load cell, connected to said processor, for measuring compression loading on said spider slips.   
     
     
         4 . The apparatus of  claim 1 , wherein said pressure circuit controls pneumatic pressure to actuate said slips. 
     
     
         5 . The apparatus of  claim 1 , wherein said pressure circuit controls hydraulic pressure to actuate said slips. 
     
     
         6 . The apparatus of  claim 1 , wherein said pressure circuit supplies hydraulic pressure to actuate one set of slips, and supplies pneumatic pressure to actuate the other set of slips.