ISO 9606 explained: qualification testing of welders

ISO 9606 is the international standard for qualification testing of welders in fusion welding: it defines the test the welder welds, what is done to that test piece to judge it, and the range of production work the resulting qualification covers. It is the standard most often named when the client, the designer or the parent company is not Australian.

What ISO 9606 covers

ISO 9606 is a personnel qualification standard, structured by material group. Part 1 covers steels and is the part most people mean when they say ISO 9606. Further parts cover aluminium and other non-ferrous material groups.

For each qualification the standard sets out:

• the welding process the test is welded with
• the test piece: plate or pipe, joint type, thickness and diameter
• the welding position
• the material group, and the consumable type including whether it is hydrogen controlled
• the examination and testing of the completed test piece
• the acceptance criteria for imperfections
• the range of approval: what the qualification covers beyond the exact test that was welded
• the period of validity and what has to happen to keep it valid

Range of approval is the whole point

Nobody welds a test piece for its own sake. The value of a qualification is the range of production welding it authorises, and every essential variable in the test determines part of that range.

Position is the clearest example. A welder tested in a difficult position generally covers easier ones, and the reverse is not true. Thickness works as a band around the test thickness rather than as a single value. Pipe diameter works the same way. A pipe test usually covers plate, while a plate test does not cover small diameter pipe. Material group and consumable type carry across in defined groupings rather than freely.

The practical discipline is to read the range on the certificate against the joints on the drawing before the welder starts, and to keep the two together in the quality file. A current certificate for the wrong range is not evidence of anything.

Validity, and why it lapses quietly

An ISO 9606 qualification is time limited, and the mechanism for keeping it alive is different from an Australian welding ticket. Continuing validity depends on the welder actually working with the process, confirmed at intervals, and the standard offers more than one route to demonstrate that: periodic confirmation by the employer or the welding coordinator that the welder has been working within the range of the qualification, or testing.

The practical failure mode is administrative rather than technical. A welder who has been welding the same joints for years loses a qualification because nobody signed the confirmation at the required interval. Put the confirmation dates in the same diary as the calibration dates.

ISO 9606 or AS 1796?

Both qualify welders. They are not the same document and one does not automatically satisfy the other.

• AS 1796 is an Australian certification scheme built around numbered certificate categories aimed at high quality welded applications, delivered through training and examination and endorsed by a certifying body. It is what Australian pressure and structural specifications usually name.
• ISO 9606 is a qualification test standard used worldwide, without a numbered certificate scheme, where the certificate records the essential variables and the resulting range.

If your specification names one, hold that one. If a project has both an Australian client and an international engineering contractor, expect to be asked for both, and plan the test pieces so that one welding session produces the evidence for each where the ranges allow.

Related standards

• ISO 15614, welding procedure qualification by test. The companion standard, and the other half of the evidence.
• AS 1796, certification of welders and welding supervisors.
• AS/NZS ISO 3834, which requires welders to be qualified and requires records proving it.
• AS 3992, the Australian pressure equipment welding qualification standard.
• Welder qualification is not procedure qualification, if the distinction is new.

Getting a copy of the standard

ISO 9606 is published by ISO and is available in Australia through Standards Australia. It is not free. Buy the part that matches the material you weld.