Page 210 - Welding of Aluminium and its Alloys

Welding procedure and welder approval 193

Table 10.11 Range of approval on diameter

Test piece diameter D (mm) Range of approval

D £ 125 0.5D to 2D
D > 125 ≥0.5D

For structural hollow sections ‘D’ is the dimension
of the smaller side.

the parent metal, provided that this does not require a change in the
welder’s technique.
The last and perhaps the most important variable from the welder’s point
of view is the welding position as shown in Table 10.12, the principle being
that a test carried out in a more difficult position approves for welding in
the easier positions. The specification requires that the test is carried out
with conditions similar to those to be used in production such as edge
preparation, position, welding time, preheat and heat input. The test piece
must have at least one stop and start in both the root run and in the capping
pass.
The test regimes for the various types of joint are given in Table 10.13.
The acceptance standard is specified in EN 30042 ‘Guidance on Quality
Levels for Imperfections’ and is specified as defect level ‘C’ for excess weld
metal, excess convexity, excess throat thickness and penetration and level
‘B’ for the remaining defects.
The welder may submit a second test piece if the first fails to achieve the
required standard. If this test piece also fails and the failure can be attrib-
uted to a lack of skill then the welder is required to be re-trained before
being permitted to attempt the test once more. Successful completion of a
test approves the welder for a period of two years although the approval
certificate must be endorsed at six monthly intervals by the employer. This
can be done provided that the welder is engaged on work within the range
of approval and that the work is of an acceptable quality. The period of
approval can be extended beyond two years by the examining body pro-
vided that the employer can produce documentary evidence such as six
monthly radiographic, ultrasonic or fracture test reports.

10.3.2 ASME IX welder approval
The ASME code covers both procedure approval (qualification) and welder
approval. Welders are divided into two categories, those who perform
manual or semi-automatic (MIG) welding and those who operate machine
or automatic welding equipment. As with EN 287 Part 2 the welder must