Double pipe forked part structure and method of making the same

A method of making a forked part of a double pipe, comprising:

• working an open end portion of an outer pipe including a tubular main portion formed with the open end portion at an axial end of the main portion into one of a spectacle shape or a figure eight shape including a tubular inner pipe supporting portion and a tubular branch pipe supporting portion, in such a manner that the inner pipe supporting portion is located inward of a main portion of the outer pipe along an extending direction of the main portion of the outer pipe;
• and
• brazing joint portions of the outer pipe, an inner pipe and a branch pipe, with the inner pipe inserted into the outer pipe through the inner pipe supporting portion of the outer pipe, and the branch pipe inserted into the branch pipe supporting portion of the outer pipe;
• wherein
• the inner pipe extends through the outer pipe via the inner pipe supporting portion and the main portion of the outer pipe.

A forked part structure of a double pipe, comprising:

• an outer pipe including a tubular main portion formed with an open end portion at an axial end of the main portion;
• an inner pipe;
• and
• a branch pipe;
• wherein
• the open end portion of the outer pipe includes a tubular inner pipe supporting portion to which the inner pipe is brazed, and a tubular branch pipe supporting portion to which the branch pipe is brazed;
• the inner pipe supporting portion and the branch pipe supporting portion are provided separately with a joint portion therebetween, forming the open end portion of the outer pipe in a spectacle shape;
• the branch pipe supporting portion is inclined with respect to the inner pipe supporting portion;
• and
• the inner pipe extends through the outer pipe via the inner pipe supporting portion and the main portion of the outer pipe.

A method of making a forked part of a double pipe, comprising:

• working an open end portion of an outer pipe including a tubular main portion formed with the open end portion at an axial end of the main portion into a spectacle shape including a tubular inner pipe supporting portion and a tubular branch pipe supporting portion, so that the branch pipe supporting portion is inclined with respect to the inner pipe supporting portion;
• and
• brazing joint portions of the outer pipe, an inner pipe and a branch pipe, with the inner pipe inserted into the outer pipe through the inner pipe supporting portion of the outer pipe, and the branch pipe inserted into the branch pipe supporting portion of the outer pipe;
• wherein
• the inner pipe extends through the outer pipe via the inner pipe supporting portion and the main portion of the outer pipe.