Hello again Tushar,

I had a look at the reference provided by Jop - good discussion.

The minimum distance between circumferential welds will vary as it depends upon the material and other factors. One thing is sure and that is that you would not want to be so close that there was an overlap of the heat affected zones (HAZ's) at the circumferential welds. Also, there would have to be enough distance to allow for the weld preparations at each end. Sometimes you must leave enough room for the preheat and post weld heat treatment coils to be placed (if the material and thickness requires it).

If you are going to make a reinforced (or unreinforced) branch connection, it would be preferable to rotate the "run" pipe during fabrication so that you do not cut through the longitudinal seam (it there is one) to make the connection. Also note that any longitudinal seams in the run pipe or the branch pipe or the reinforcing pad will affect the calculations for the "area replacement” reinforcing pad (if required).

One of my friends in Texas told me: "Do not make the welds so close that they can be covered by one piece of X-ray film. We do not want the radiographs for one weld to show the defects in an existing weld"!!!! I suppose there is a little truth in that

Regards, John.