Ovality in Pipes Research Papers (original) (raw)
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Pipelines are one of the most important elements of offshore oil and gas production system. Subsea pipelines can be instable so mattresses are put on them to avoid this problem. These mattresses are made of concrete and their interaction... more
Pipelines are one of the most important elements of offshore oil and gas production system. Subsea pipelines can be instable so mattresses are put on them to avoid this problem. These mattresses are made of concrete and their interaction with the pipeline is studied in this dissertation
A pipe section is designed using DNV rules and a Finite Element Model is created in ANSYS to analyze the effect of the mattress’ load on the pipe. Different responses are extract from the Finite Element
Analysis, in particular the frequency response and the mechanical behavior of pipes with different mattresses lengths and loads. Also, the ovalization of the pipe is evaluated.
The study concludes that the mattress load do not change the eigenvalue buckling of the pipeline structure. However, there is around 0.2% ovalization due to the effect of the mattress. This value should
be added to other uncertainties in the design process to reduce the risk of pipeline failure. For the designed pipe this ovalization corresponds to 3% reduction in the collapse pressure of the pipe.
Moreover, the location of maximum ovalization is defined around nine meters from the mattress edge and therefore this location should be the focus in inspection operations.
Ovality generally known as ‘Out of Roundness’ is one of the most common defects in pipe manufacturing. Ovality in early stages makes manufacturing process time consuming and less efficient. After dispatching, because of improper handling,... more
Ovality generally known as ‘Out of Roundness’ is one of the most common defects in pipe manufacturing. Ovality in early stages makes manufacturing process time consuming and less efficient. After dispatching, because of improper handling, ovality turns into barrier of proper welding of two pipes on site. In this paper, there is inclusion of causes of ovality, stages of ovality, drawbacks of oval pipes, manufacturing difficulties due to ovality and how to control it is included.