Connection and elbow in a gas appliance
View Patent ↗A connection is provided whereby a first tube, which may be bent into an elbow, has at least one end flow drilled. During the flow drilling process the first end is shortened, reduced in thickness, and most importantly, the inner diameter is increased to accept a second tube. Before connecting the second tube, the first end is preferably tapped with threads which can receive a nut and the nut captures an end of the second tube, preferably entrapping one of at least one bead and a ferrel to provide a connection.
1. A method of manufacturing an improved connection comprising:
proving a steel length of a first tube;
bending the first tube at an elbow;
at a first end of the first tube, flow drilling the first tube at a first end thereby increasing an inner diameter at the first end at least about 1.5 times, and then tapping internal to the first end to provide threads.
2. The method of claim 1 wherein during the step of flow drilling the first tube, increasing the inner diameter at the first end about 1.5 to about 3 times.
3. The method of claim 2 wherein during the step of flow drilling the first tube, increasing the inner diameter at the first end to about 2 times.
4. The method of claim 1 wherein during the step of flow drilling the first tube, achieving a wall thickness reduction of at least about 25% while increasing the inner diameter at the first end.
5. The method of claim 1 during the step of flow drilling the first tube, shortening a length of the first tube at the first end while increasing the inner diameter at the first end.
6. The method of claim 1 further comprising the step of capturing a second tube at the first end with a nut screwed into the threads.
7. The method of claim 6 wherein during the step of capturing the second tube, one of at least one bead and a ferrel about an exterior surface of the second tube is captured near an end of the connected tube intermediate the first and second tubes.
8. A method of manufacturing an improved connection comprising:
proving a steel length of a first tube;
bending the first tube at an elbow;
at a first end of the first tube, flow drilling the first tube at a first end thereby shortening a length of the first tube at the first end while increasing an inner diameter at the first end, and then tapping the first end to provide threads.
9. The method of claim 8 wherein during the step of flow drilling, shortening the first end at least 0.075 inches; and further comprising the step of capturing a second tube at the first end with a nut screwed into the threads.
10. The method of claim 8 wherein during the step of flow drilling, achieving a wall thickness reduction of at least 25%; and further comprising the step of capturing a second tube at the first end of the first tube with a nut screwed into the threads with one of at least one bead and a ferrel about an exterior surface near an end of the second tube captured by the nut in the first end to provide a connection.
11. The method of claim 8 wherein during the step of flow drilling, increasing the inner diameter at least about 1.5 times; and further comprising the step of capturing a second tube at the first end of the first tube with a nut screwed into the threads entrapping one of at least one bead and a ferrel about an exterior surface of the second tube near an end of the second tube to provide a connection.