B16.25 Table 1,I-1; Dimensions of Welding Ends gives values for NPS down to 2-1/2". Where could I obtain dimensions for buttwelding ends less than 2-1/2"?
Small welds (2" and smaller) are hard to make manually. Thus most fittings for small welds are of the socketweld type. If you >NEED< buttwelded connections in small pipe, there are the orbital welding machines that align the pipe and lay down the appropriate bead. One is Astro-Arc:
Check Mark's Handbook, Fittings for steel pipe, page 8-211. Fig 8.7.15
The joint prep is initially cut off square.
The end is beveled 37.5 degrees +-2.5 degrees. The edge is maintained square 1/32-3/32"
If you use the Astro-Arc I mentioned before, you cut off the joints square. there is a fitting that centers, guides, and provides the filler material.
You can design a "not standard" buttwelding end following the figures of B16.25(for small sizes fig.2) using the outside diameter and the thickness of the pipe (for example B36.10 dimensions). In this way you can calculate the inside diameter of weld preparation.
Usually, for cast products, B16.25 includes an addictional thickness on outside diameter of the schedule, while inside diameter is the same. For small diameters 1-2mm on OD may be enough to consider casting defects.
In the same way you can do also buttwelding ends for bigger sizes when pipe thickness or outside diameter are different from the ones in ASME B16.34.
Francesca
