A comparison is made between the pressure distributions in identical brass and nylon pipe-lines conveying polystyrene powder, showing that electrostatic charging of the solid particles has a negligible effect on highspeed, gas-solids pipe flow. A theory is presented for the prediction of the electrostatic charging rate of the solid particles. It is predicted and confirmed experimentally that the current to earth from electrically isolated sections of the brass pipe and from aluminium foil wrapped on a length of the nylon pipe varies linearly with the solids loading.

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In the event of an accident, an industrial plant must be capable of being shut down in a safe, controlled manner. Thus, when a plant containing high-pressure fluids is being designed, the potential damage to essential shut-down equipment resulting from rupture of the pressure envelope must be assessed and, where necessary, protection provided. For example, pressure vessel rupture may generate missiles; i.e., sections of the pressure envelope become detached and are accelerated to significant velocities by the expanding fluid contents. An assessment of the consequences of pressure vessel rupture must therefore include estimates of the likely extent of the missile impact zone and the potential damage to equipment within that zone, which are both functions of the missile velocity. This paper describes preliminary guidelines for defining the velocity of the various types of missile which can be generated by pressure vessel failure. The recommended velocities are based on experimental evidence, including a large body of previously unpublished BNL (Berkeley Nuclear Laboratories) data. The extent of the hazard zone is also considered.