EEMUA 180:2007

Under abnormal operating conditions, vertical fixed roof storage tanks may experience rapid increases in vapour pressure which overwhelm venting devices and lead to tank failure. EEMUA 180 gives guidance to designers and users of such tanks on the practical steps that can be taken in design, operation and maintenance to predispose the roof-to-shell joint to fail in preference to the shell-to-bottom joint, thereby ensuring retention of the tank's contents. Such relatively weak roof-to-shell joints are known as 'frangible roof joints'. Guidance is also provided on how to determine the actual frangibility of tanks built before 1985 (the date where frangibility became known as a design requirement).