This section is from the book "Practical Sheet And Plate Metal Work", by Evan A. Atkins. Also available from Amazon: Practical Sheet And Plate Metal Work.
Figs. 331 and 332 show outside and sectional views of the way in which an outlet may be brazed on to a pipe. The outlet is flanged to fit on the main pipe as shown, whilst the hole in the latter is made small to begin with and gradually worked out to the required size. After being thoroughly cleaned the two are wired together and carefully brazed,

Fig. 331.
 
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