ABSTRACT
Where large numbers of welds are involved in a project, or when a construction involves a large number of welds, a sample only is often proposed for inspection and acceptance purposes. If 100% inspection (or NDT) is specified it must be made clear whether this means 100% of each and every weld, or one inspection (e.g. one radiographic shot) of each weld. '100% inspection' is a dangerous expression and largely meaningless without specifying which method of inspection should be used (i.e. visual or NDT) and to what standard it should be taken (i.e. what are the criteria for acceptance?). Beware also of simple sampling statements such as ' 10% radiography;. Which 10% should it be? 10% of each working shift, or 10% of all welds per day, or of each welder's work, or on each component? Should butt welds, which are relatively easy to examine by NDT, be covered to the exclusion of fillet welds or does the percentage apply to both butts and fillets? What about the attachment welds? It is for such reasons that each construction needs inspection procedures as part of the quality /inspection plan.
