1.1 General
This Standard covers the preparation of buttwelding
ends of piping components to be joined into a piping
system by welding. It includes requirements forwelding
bevels, for external and internal shaping of heavy-wall
components, and for preparation of internal ends
(including dimensions and tolerances). Coverage
includes preparation for joints with the following:
(a) no backing rings
(b) split or noncontinuous backing rings
(c) solid or continuous backing rings
(d) consumable insert rings
(e) gas tungsten arc welding (GTAW) of the root pass
Details of preparation for any backing ring must be
specified when ordering the component.

1.2 Application
This Standard applies to any metallic materials for
which a welding procedure can be satisfactorily
qualified, but does not prescribe specific welding processes
or procedures. Unless otherwise specified by the
purchaser, it does not apply towelding ends conforming
to ASME B16.5, B16.9, or B16.47.


Click here for PDF http://ASME-ANSI-B16.25-2012-butt-welding-ends

if you want to check the detail standard content, you can buy from following link: