Insertion valve and installation method

A valve assembly for insertion in a line formed by an existing pipe of predetermined outside diameter containing fluid under pressure, the valve assembly comprising:

• a first subassembly that includes a valve body having opposite first and second ends, a valve body axis extending between the first and second ends, and a bonnet-supporting flange intermediate the first and second ends that defines an access opening facing radially away from the valve body axis, the valve body being adapted to be assembled over the existing pipe so that the pipe extends along the valve body axis between the first and second ends of the valve body and so that a user can access the pipe within the valve body through the access opening for purposes of cutting and removing a section of the existing pipe in order to form a gate-receiving gap in the pipe;
• and
• a second subassembly that includes a bonnet having a gate and a flange-mating portion, the bonnet being adapted to function as means for moving the gate through the access opening into the valve body, between an open position of the gate in which the first and second ends of the valve body are in fluid communication and a closed position of the gate in which the gate extends through the gate-receiving gap in the pipe and into fluid-tight engagement of the valve body such that the first and second ends of the valve body are not in fluid communication;
• wherein the flange-mating portion of the bonnet defines a gate opening through which the gate extends from the bonnet in a fluid-tight fit;
• and
• wherein the flange-mating portion of the bonnet fits into the access opening in a fluid-tight fit;
• thereby enabling a user to mount the bonnet on the valve body through a temporary isolation valve mounted on the bonnet-supporting flange in order to facilitate insertion of the valve assembly when the existing pipe contains fluid under pressure;
• wherein said first and second ends of the valve body are not connected to each other solely by valve body structure that is rotatable about the valve body axis independent of the first and second ends;
• wherein said first and second ends of the valve body are not rotatable about the valve body axis relative to each other;
• wherein said bonnet-supporting flange is not rotatable about the valve body axis relative to the first and second ends;
• wherein the access opening is sufficiently large to receive a hole-cutting element having an outside diameter no smaller than the predetermined outside diameter of the pipe as the hole-cutting element advances radially relative to the valve body axis through the access opening toward the pipe;
• wherein the valve body defines a hollow interior that is sufficiently large to receive the hole-cutting element as the hole-cutting element rotates and advances radially entirely through the pipe to form the gate-receiving gap in the pipe;
• wherein the gate is adapted to extend, in the closed position of the gate, through the gate-receiving gap in the pipe and into direct fluid-tight engagement of the valve body without needing to rely on contact with the pipe to effect a seal.