Page 208 - Welding of Aluminium and its Alloys

Welding procedure and welder approval 191

10.3 Welder approval

While the procedure approval test is performed to demonstrate acceptable
mechanical properties, the welder approval test is carried out to demon-
strate that the welder has a sufficient level of skill to deposit weld metal of
an acceptable quality. A similar philosophy to that for procedure approval
is adopted – a number of standard tests are called up in the standards, suc-
cessful completion of which gives a range of approval for a number of essen-
tial variables. Since the purpose of the test is to assess the skill of the welder
the essential variables are different from those of the procedure approval
test. The specifications most frequently encountered are BS EN 287 Part 2
and ASME IX.

10.3.1 BS EN 287 Part 2
BS EN 287 Part 2 complements the procedure approval specification BS
EN 288 Part 4. The specification regards the welding process as an essen-
tial variable and restricts the processes covered by the specification to MIG,
TIG and plasma-arc welding although other processes may be approved by
agreement (Table 10.8).
Materials are grouped for the purposes of approval as follows:
• Group W21, pure aluminium and aluminium–manganese alloys with less
than 1.55Mn;
• Group W22 non-heat-treatable alloys;
• Group W23 heat-treatable alloys.
Dissimilar metal joints are treated in a similar manner with a test piece
made in one group conferring approval to weld a number of combinations
as shown in Table 10.9.

Table 10.8 Material groups for which the welder is
approved

Test piece material group Range of approval

W21 W22 W23
W21 * X —
W22 X * —
W23 X X *

* Approved group.
X Group also approved.
— Not approved.