Device for preventing pipe buckling

Abstract

An apparatus for preventing pipe buckling when downwardly directed axial forces are applied to a pipeline (3) which extends from a derrick (1) down into a well bore, especially when snubbing. The apparatus comprises two sets of pipe supports (8) linked together to give a continuous chain (10), which is arranged to extend from a respective guide rail (6, 7) in the derrick (1) to the pipeline (3), and the pipe supports (8) are movably arranged in the guide rail (6, 7) parallel to the pipeline (3). The guide rail (6, 7) extends in a general U-shape with the U-bend (6c, 7c) located closest to the lower end of the derrick (1) and comprises two legs (6a, 6b, 7a, 7b), of which a first leg (6a, 7a) is arranged close to the pipeline (3) and a second leg (6b, 7b) is arranged at a greater distance from the pipeline. The pipe supports (8) are designed to be placed in the first leg (6a, 7a) when operative, and are designed to be transferred to the second leg (6b, 7b) when they are to be rendered inoperative.

Dependencies are inferred from the claim text.