On-board high-pressure storage of hydrogen gas and compressed natural gas is critical to the widespread adoption of alternative gaseous fuel to reduce CO 2 emissions in transportation. Cylindrical pressure vessels are the traditional option for on-board gaseous fuel storage; however they possess domed heads that are prone to over-design and a source of manufacturing difficulties. Toroidal composite pressure vessels (CPV) have been recognised as a volumetrically efficient solution that could address these problems, thus reducing vessel mass, while improving storage efficiencies. Currently, there exist many gaps in toroidal CPV research which must be addressed to fully realise the potential of this technology. Herein we present a comprehensive and critical review of the design and optimisation of toroidal CPVs, focusing on damage tolerant design as a key requirement to meet safety standards and optimisation of toroidal cross-sectional profiles (shape, thickness variation and fibre winding pattern) to reduce or eliminate stress non-uniformity. An original analysis of toroidal radius ratio (R/r) influence on the thickness profiles of naturally-thickened and isotensoid circular toroidal CPVs is conducted. It is concluded that a focus on smaller radius ratios (1.25 < R/r < 3) is required to maximise the potential spacesaving and volumetric efficiencies of the torus. Leading international CPV standards are analysed in order to adapt three important design qualification requirements from cylindrical to toroidal structures. Building block approaches are also presented to aid the damage tolerant design of toroidal CPVs for the relevant design qualification tests.

Parametric formulae derived for offshore structural tubular joints have been assessed for potential use for estimating stress intensification factors for pipe stress analysis. The background to these equations is given and comparisons made for a range of typical geometries. Despite the absence of a "plug" of material in a pipe joint, the tubular joint equations appear suitable for the estimation of stress intensification factors for fabricated tees subjected to moment loading of the branch. It is considered that this approach should be investigated further by code developers.