Page 198 - Welding of Aluminium and its Alloys

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Welding procedure and welder approval

10.1 Introduction

Very often the decisions on how a weld should be made, filler metal and
welding parameter selection are left to the welder. While this may be
acceptable in those situations where the weld quality is only incidental to
the integrity of the fabrication it is not acceptable where the weld is crucial
to the performance of the component. The need for approved welders to
work to approved welding procedures is also often a requirement of either
the application standard to which the fabrication is designed and con-
structed or a contract specification requirement. Aside from these specifi-
cation requirements it may be necessary for the fabricator to be able to
demonstrate to clients, to regulatory authorities or, should a failure leading
to loss or damage occur, to a court of law that the welds have been made
to an acceptable quality.To specify how both the welds and the welders may
be shown to be acceptable there are a number of standards available to the
engineer. The requirements of some of these standards are covered in this
chapter.
It cannot be emphasised too strongly that the detail below is only a
summary of the specification requirements and must be treated with
caution. Although best efforts have been made to ensure that the abstracts
are accurate, they are only abstracts and accurate at the time of writing.
Where compliance is a standard or contract requirement the latest edition
of the approval standards must be consulted.

10.2 Welding procedures

A welding procedure or weld procedure specification (WPS) is a written
instruction that specifies materials, consumables and edge preparations for
a given joint. It lists the pre- and post-weld operations including heat treat-
ments; machining, grinding and dressing of the weld; details the welding
variables and the run sequence; and may specify the acceptance criteria and

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