Piping structure and process and pipe construction method

A process for forming an opening in a pipe, comprising:

• a step of attaching a rotating unit around the pipe, the rotating unit being rotatable in a circumferential direction of the pipe, wherein a cutter having a milling-shaped cutting tool is attached to the rotating unit;
• a skin formation step of revolving the cutting tool in the circumferential direction of the pipe together with the rotating unit while rotating the milling-shaped cutting tool about a central axis of the tool, thereby cutting an outer surface of the pipe to form a groove on the pipe, the groove being elongated in the circumferential direction and having a bottom that is formed as a skin;
• a removal step of removing shavings produced from the cutting;
• and
• a step of thrusting through the skin to form the opening, after performing the skin formation step and the removal step.

A pipe construction process for obtaining a piping structure, the piping structure including a gate valve body assembled into a pipe, the piping structure comprising:

• a pipe that defines a groove extending in a circumferential direction, the groove having a bottom that is formed as a skin;
• a case that encloses a portion of the pipe including the groove having the bottom;
• a gate valve body that is arranged in the case;
• and
• a valve rod that brings the gate valve body closer toward the groove and further moves the gate valve body so as to thrust through the skin of the bottom of the groove to form an opening,
• wherein the gate valve body includes:
• a circular-shaped valve main body that enters an inside of the pipe;
• a blade that is provided on a distal end side of the valve main body for breaking the skin to form the opening;
• and
• a seal portion that is provided on a proximal end side, which is opposite to the distal end side, and contacts a portion of the pipe around the opening to shut the opening,
• the pipe construction process comprising:
• a step of attaching a rotating unit around the pipe, the rotating unit being rotatable in the circumferential direction of the pipe, wherein a cutter having a milling-shaped cutting tool is attached to the rotating unit;
• a skin formation step of revolving the cutting tool in a circumferential direction of the pipe together with the rotating unit while rotating the milling-shaped cutting tool about a central axis of the tool, thereby cutting an outer surface of the pipe to form the groove on the pipe, the groove being elongated in the circumferential direction and having the bottom that is formed as the skin;
• a removal step of removing shavings produced from the cutting;
• a step of removing the rotating unit and the cutter from the pipe;
• and
• a step of attaching the case accommodating the gate valve body therein to the pipe so that the case encloses the portion of the pipe including the groove having the bottom.