The above was the situation for HHNK (see also project ‘Beoordelingsmodel AC persleidingen‘ – in Dutch). The DN900 pipeline Hoorn was moved and provided the ideal opportunity to inspect and test the pipeline.
HHNK put in a lot of effort to get the necessary information. Besides, external knowledge sources were consulted to collect as much comparable research as possible. This was combined with Thymolphthalein tests, results of destructive testing and field tests. We developed a mathematical assessment model, in which the original design was compared to the current acceptable standards.
On the basis of this approach it was possible to develop a generic assessment model for HHNK. With this model we are able to do an substantiated check of the remaining AC fields.
The model provides HHNK the necessary insight into:
- Remaining safety in the pipeline;
- Influence of individual factors (e.g. What will vacuum pressure cause in this pipeline?).
This model includes i.a. the essential behaviour of the material, environmental factors and (future) usage, and shows the impact of specific changes in a comprehensible manner.