An interesting question. ASME IX specifically discusses the qualification tests required for groove and fillet welds, but not plug welds. QW-402.1 is a nonessential variable, but it only mentions groove welds. My inclination would be to say that since a groove weld qualification qualifies for groove and fillet welds, then it should also qualify plug welds. If we were plug welding a liner to a duct, or something similar, we would use a WPS qualified for groove welds. D1.1 has the following statement in 4.29:
"Qualification for CJP groove welds on tubular or nontubular
connections shall qualify for all plug and slot
welds."
If you are doing this for a customer and they have raised a question, then you could perform a workmanship sample using the proposed hole diameter and material thickness, cut it in half across the plug, and perform a macroetch.
QW/QB-492 Definitions
plug weld: a weld made in a circular, or other geometrically
shaped hole (like a slot weld) in one member of a lap or
tee joint, joining that member to the other. The walls of
the hole may or may not be parallel, and the hole may be
partially or completely filled with weld metal. (A filletwelded
hole or spot weld should not be construed as conforming
to this definition.)
""I believe that makes it clear that fillet weld criteria does not apply."
Aws 3.0 01
Slot weld. A weld made in an elongated hole in one member of a joint
fusing that member to another member. The hole may be open at one end.
A fillet welded slot is not to be construed as conforming to this definition.
See figure 15(D).
""AWS is consistent with ASME in this.""
Back to section IX:07 QW/QB-492 Definitions
lap joint: a joint between two overlapping members in
parallel planes.
single-welded lap joint: a lap joint in which the overlapped
edges of the members to be joined are welded along the
edge of one member only.
QW-202.2 Groove and Fillet Welds
a) Qualification for groove full penetration
b) qualification for partial penetration groove welds
c) qualifications for fillet welds
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In my opinion, both ASME and AWS make a very important distinction in the definition of "plug welds",
that gives specific direction as to what criteria to apply to plug welds for qualification. The specific
exclusion of fillet weld criteria in the definition and the inclusion of the words partial and complete fill,
would, if not directly, give direction to treat qualification the same as you would a partial or full pen.
Should this be the case, applied linings would have to have some specific redirection, or be in contradictory
to the applied definition.
The following is the direction on applied linings again in 07 IX:
That distinction is in that
QW-218 Applied Linings
QW-218.1 WPSs for attaching applied linings shall be
qualified in accordance with QW-202.2(a), (b), or (c).
QW-383.2 Applied Linings
(a) Welders and welding operators shall be qualified
following the rules for making groove or fillet welds in
accordance with QW-301. Plug welds for attaching applied
linings shall be considered equivalent to fillet welds for
the purpose of performance qualification.
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There is the logical specific exclusion in regards to treatment/definition of plug welds.
This to me gives a specific logical path and direction.
That's my two cents worth.
Regards,
Gerald