The demand for pipe materials that can withstand increasing hydrostatic pressures continues to grow as oil and gas exploration takes us into deeper and deeper waters. As water depth increases, failure by hydrostatic collapse becomes more likelyas the limiting failure mode for pipeline design. In general, pipes for deepwater applications possess a diameter to thickness ratio in a region where failure is dominated by both instability and plastic collapse. This implies that, prior to failure, the compressive yield strength of the material must be exceeded, followed by ovalisation and further local yielding.To enable effective design work to be performed, and proven during service, it is necessary to ensure that the mechanical and dimensional properties of the pipe material are controlled within very strict boundaries and reliable and accurate formulae are required to take into account these factors. However, mechanical equations for this simple failure mode have not been satisfactory established. Current existing formulations use basic mechanical expressions that are calibrated to some limited test data. However none of these expressions examine the actual mechanics of the failure mechanism. This paper presents an investigation into the mechanics of this specific problem and permits a simple assessment of the effects of geometrical and material data on the collapse pressure of moderately thick tubes. An analytical expression has been generated and correlated to extensive test data and finite element models, proving the accuracy of the expression. The resulting formula also allows a deeper understanding of the effect pipe shape has on collapse and opens to the door for manufacturers to further enhance pipe material performance. Despite the complexity of the collapse mechanisms this work presents a concise yet rigorous and effective analytical approach.The work presented in this paper will form the basis of future investigations that will enhance the understanding of this failure mode in pipelines. This will lead to increased pipeline safety while allowing the boundaries of pipeline application to be challenged, enabling hydrocarbon recovery in deeper and deeper waters.