Abstract: A method and apparatus for stopping or otherwise altering fluid flow in a pipeline at a desired location, originally without provisions to do so, and particularly suited for use with heavy wall pipes. The method and apparatus includes use of chip forming cutting tools that are carried in a circumferential orbit around the pipe within a housing assembled around the pipe. The cutting tools are progressively advanced into the wall of the pipe to cut two axially spaced circumferential grooves in the pipe wall. Thereafter, a shear plate with cutting edges coinciding with the grooves can be forced through the pipe to sever a coupon from it and thereby gain access and control over flow through it.