Publications
| Title | | Authors |
|---|---|
| Collapse behaviour of seamless pipe for offshore applications « back |
U Marewski, Y Tkach, G Cumino, J-P Jansen, G Mannucci, S Zimmermann and M Zarea |
| 16th Joint Technical Meeting, Canberra, Australia, April 2007 | |
| Offshore pipelines are now being installed in ever increasing water depths. The design of such deepwater pipelines requires the acquisition of additional data on mechanical properties and determination of possible geometrical variations within the pipe. These properties have a major influence on the collapse strength of the pipe, and subsequently govern the maximum water depth at which the pipe can be used. Cold deformation introduced during pipe laying operations (e.g reel-lay) induces changes in the material properties important to design of the pipe. This paper presents a programme of work investigating the dimensional and mechanical properties of seamless pipe in three conditions: as-received (with simulated coating), simulated reeled & straightened and simulated reeled & straightened with subsequent ageing heat treatment according to DNV rules. Collapse tests with seamless pipe in both its as-received, reeled & straightened and heat-treated condition have been performed within the scope of this project. The results from both the small-scale and collapse tests confirm that heat treatment is effective in restoring and improving the collapse resistance of seamless pipe. As a part of the work, the collapse tests were analysed using both the standard and a modified DNV equation. The modified equation takes into account the use of end caps in the collapse tests and their effect of increasing biaxiality of the stress state in thick-walled pipes and hence the apparent increase in collapse resistance. The data obtained indicate that the use of end caps in the collapse tests could lead to non-conservative results due to the presence of the axial load from the end cap. | |
| Paper request | |