Individual site operations can vary from a single small repair involving one welder, to large multicontractor
projects costing millions of pounds. Quality and reliability is equally important in both cases, as
lapses in control can jeopardise the security of the whole plant. There are numerous examples of small
apparently insignificant faults, arising from malpractice, causing major failures. For example, the crane
gantry illustrated in Fig. 1 failed by brittle fracture which initiated from a poorly repaired drilled hole in the
web of the gantry girder. No reason could be given for the drilled hole being in the web. It had probably
arisen as an error during the fabrication stage and was repaired without any approval. It is doubtful whether
any competent person was consulted regarding its significance. However, it was the prime factor in the
collapse of the gantry with the loss of three overhead cranes and incalculable disruption to production. It is
doubtful if any control system could completely eliminate such negligence. Clearly, the work must conform
to the designer’s requirements. If the design does not show a poorly repaired hole then it should not be there
and, in the absence of authority from the designer, the very minimum requirement must be that an effective
repair is confirmed by 100% inspection using either radiographic or ultrasonic techniques as appropriate.
A system for quality control is therefore of paramount importance and the customer should protect his
interests, for which he has a statutory responsibility in certain high-risk areas such as offshore oil
development. It is doubtful in the case of the collapsed crane gantry whether identification of the culprit and
successful prosecution of claims for damages or insurance cover would recover the total costs of the
damage, but for a fraction of that cost, properly invested in quality control at the manufacturing and
construction stages, the problem may well have been avoided.