FORMING A CABLE ENTRY OR EXIT BRANCH ON A FLUID PIPELINE WHILE THE PIPELINE IS IN OPERATION

摘要

A cable entry or exit pipe (30) is formed on a fluid transportation pipeline (10) whilst in normal operation full of and transporting a fluid under a positive pressure, by a method which comprises the steps: (a) producing two semi-cylindrical shells (14,16), one (14) of which carries an oblique branch pipe (30) and has an aperture (34) aligned with the bore of the branch pipe (30); (b) securing in a fluid tight manner around the pipeline (10) the two shells (14,16) so as to form a reinforcing collar (12) carrying an oblique branch pipe (30) lying at an acute angle suitable for the entry into and exit from the pipeline (10) of a cable (68); (c) securing in a fluid tight manner to the free end of the branch pipe (30) an isolating valve (62); (d) securing in a fluid tight manner to the free side of the isolating valve (62) a fluid tight drilling apparatus (70) equipped with a drill bit; (e) opening the valve (62) and introducing the drill bit through the opened valve (62) into the branch pipe (30); (f) rotating and progressively advancing the drill bit into contact with and through the wall (38) of the pipeline section (10); (g) withdrawing the drill bit and closing the valve (62); and (h) removing the drilling apparatus (70). Preferably, a liner (40) inserted into the branch pipe (30) between steps (g) and (h) serves as a cable guide.