Scale considerations for fire testing of pressure vessels used for dangerous goods transportation

Fire protection of pressure vessels for transport and storage of dangerous goods is an active topic of research around the world. In many cases, organizations are conducting theoretical analysis followed by fire testing of thermal protection systems to determine how long they delay thermally induced failure, or if they eliminate failure. In most recent cases the organizations chose to do small scale fire testing because of the obvious cost savings.The question then is – are small scale experiments representative of highway tank truck and rail tank car scales? This paper discusses the scale issues involved. It goes on to show how identical fire heating conditions can give dramatically different failure times and modes of failure for small and large scale tanks if the conditions are not truly similar.

► fire testing of thermal protection systems for dangerous goods pressure vessels is usually done in small scale to save cost.
► there are considerable scale issues due to nonlinear effects.
► differences in fire heat transfer, high temperature stress rupture and PRV behaviour can dramatically change time to failure.
► example is presented to show these scale effects.
► it is suggested that final proof testing should be done in full scale