ASME BPV Code Section I,
PW-41.2.2, Single-Welded Butt Joints

ASME BPV Code Section I, 2023 Edition, PW-41.2.2 requires that butt joints welded from one side only, described as single‐welded butt joints, shall have full penetration at the root of the weld. It further requires that this be demonstrated in the qualification of the weld procedure used to make the weld. A reference was also added to PW-28.1.3 (incorrectly shown as PW-28.1.4, which has been corrected by errata) to clarify several inquiries received over time regarding the demonstration of single-welded butt joints.

This statement emphasizes that, under Section I, for butt joints welded from one side only, welded joint design is considered an essential variable for weld procedure qualification. It further notes that no additional testing requirements of such a qualification test are required above those specified in Section IX, e.g., tension and bend tests.

It has become clear that since these revisions were made, some Code users were not aware of the requirements of PW-41.2.2 despite their presence in Section I since the Winter 1975 Addenda of the 1974 Edition.

Based on comments received, and interpretation inquiries sent to Section I since the publication of the 2023 Edition of the Code, we offer the following opinions:

1. If a butt joint is to be welded from one side only, e.g., a single welded groove, this must be demonstrated by the supporting qualification record, i.e., the qualification coupon must also be welded as a single-welded butt joint.
   1. A double-sided or backed Weld Procedure Qualification Record (PQR) may not be used to write a     Welding Procedure Specification (WPS) to make a production weld from one side only.
   2. A single-welded PQR may be used to write a WPS to make a double-sided or backed production weld.
2. Other variables regarding joint design, provided in the Tables of Section IX QW-250 for groove design, such as QW-402.1 (a change in the shape of the groove, i.e., V to J, to U to ½ V, but not backed or back-gouged) and QW-402.10 (a change in specified root spacing) remain nonessential.
3. QG-108 of Section IX allows use of WPS and PQRs made to earlier Editions or Addenda of Section IX for welding of pressure parts to which a current Edition of a construction Code is specified. However, in line with QG-100(b) and QG-108, if the construction code has had revisions since the date of the WPS and PQR, then those documents need to reflect those revisions.
   1. In this case, any WPS qualified since the Winter of 1975 for welding single-welded joints under Section I rules should have had the PQR qualified as such.
   2. If a WPS/PQR was qualified predating Winter 1975 and was not qualified as single-welded, i.e., with back-gouging of backing, then an alternative WPS appropriately qualified in accordance with PW-41.2.2 is required.