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Acceptance Testing

What is Acceptance Testing?

• "Acceptance Testing" is a term commonly used to describe the independant inspection of the quality of metal finishes such as anodizing and powder coating.
• The desirability of such testing became apparent during the 1980s when it was realised that the failure of the metal finish of a curtain walling system, for example, could necessitate the replacement of the complete system even though the cost of the metal finishing had been a very small percentage of the original cost of the works.
• The purpose of acceptance testing is solely to confirm that the products supplied comply with the specification. It goes without saying that the specification must be appropriate in the first instance.

Why is Acceptance Testing necessary?

• Powder coating : Although the technology of the powder themselves has improved considerably over the last decade, the quality of the finished product is still totally dependant on the quality of the application, and this is still highly variable. The most common failures of powder coating are inadequate cure and adhesion, poor colour-matching and surface finish, and incorrect film thickness.
• Anodizing : It is impossible to confirm compliance with the British Standard by visual inspection alone and some form of testing is highly desirable. The most common failures of anodizing are inadequate surface hardness and incorrect film thickness.

How is Acceptance Testing carried out?

• Independant testing is normally carried out at the applicator's plant before the finished products, most commonly aluminium extrusions, are dispatched to the fabricator for assembly.
• Non-destructive tests may also be carried out on site, on the installed system, although the consequences are clearly greater if the product is then found to be defective.
• The specification of acceptance testing is covered by NBS clauses Z31/235 and 241, and Z33/250 and 260.

Who carries out Acceptance Testing?

• Acceptance testing is a highly specialised field which supports only a very small number of practitioners. The AASC publishes a list (Technical Information Sheet 8) of independant test authorities but of these, as far as we are aware, only Clive Plant has a website [www.cliveplant.co.uk].
• Specifiers should be aware that some of the independant test authorities will only issue their reports to their "client" - normally the specialist cladding contractor - and not to the design team. This has the potential to disguise problems at the applicator's plant - the design team only see the tests which pass, not those that fail - although this is, thankfully, a rare occurrence.

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