Edward Ingham, Mike Shepherd
Papers # 2014 Chicago
Exova has previously demonstrated that under normal operating conditions PE 100 pipes would be expected to have a lifetime of over 200 years, but in the UK concerns have been reported about relatively high failure rates within the water utilities of fusion joints, particularly for large diameter pipes. For some time, the principal concern has been electrofusion joints, but there have even been instances of failure of butt fusion joints in larger diameter, thicker sections. This is both surprising and unexpected because with good site practice, using the correct specifications and equipment, this situation should never arise. However, it would be wrong to turn a blind eye to the occurrence and the correct approach is to address the problems by eliminating the root cause, which is widely recognised as poor site practice that usually stems from issues with the training of welding personnel.
The long term integrity of both butt fusion and electrofusion welds in service is highly dependent on the competence of the personnel engaged in their installation and the UK water industry has realised that current systems for the training and certification of site operatives undertaking fusion welding operations are not adequate. Accordingly, the Water UK Standards Board has commissioned Exova to use its technical expertise to co-ordinate the preparation of a Water Industry Specification (WIS) to set out the requirements of a comprehensive training and certification scheme for site based fusion welding operatives. The document is being prepared by representatives from water utility companies, contractors, training providers and pipe and fitting suppliers, which demonstrates both the level of concern and the commitment to provide a solution. This paper provides the background and solution to the problem, giving the key elements of the first draft of the standard that will be developed by the steering committee of industry representatives to ensure that a step change improvement in site performance can take place and allow future installations of PE pipe in the UK to reach their full potential.
