ABSTRACT

Design of pipes in the offshore industry implies use of design equations with appropriate safety factors to predict the resistance against failure modes such as burst and excessive plastic deformation. Analytical based equations for prediction of pipe burst and yielding deformation mode of failure is compared with finite element analysis and tests in this paper. Review and comparison are made of burst and excessive yielding design limitations in various design codes. The comparison can provide knowledge to engineers about design possibilities based more upon the properties of the materials than has been done in the past. This can in future result in wall thickness and cost savings.

INTRODUCTION

From the standpoint of the pipe designer it is important to have design equations against structural failure which gives consistent factors of safety against burst from gross over-pressure or against gross plastic deformation from extreme combined load conditions. In choosing design equations for design codes, consideration must be given to simplicity, availability of material data and accuracy. If, due to unavailable variations in materials, the accuracy cannot be high, it must be known what the accuracy is so that adequate safety factors can be applied. The traditional hoop design and yon Mises based component stress formulations in many design codes may be conservative compared to test and elastic plastic finite element results. There is thus a motivation to develop more rational design equations for burst and plastic deformation modes of failure. The purpose of this article is to compare candidate straight pipe design equations, see Kirkemo (2001), to be used for design against burst and gross (excessive) plastic deformation with tests and finite element analysis. In light of these comparisons, design criteria from various design codes are compared for these failure modes.

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