In order to determine the effective load of gas phase detonations on pipe walls (“static equivalent pressure”), comprehensive experiments have been conducted in 48.3×2.6 and 114.3×3.6 pipes (outer diameter [mm] × wall thickness [mm]), in which deflagrative explosions of stoichiometric C2H4/O2/N2-mixtures at 20 °C underwent the transition to detonation. Initial pressures were chosen high enough to produce detonation pressures that caused significant bulging of the pipe walls.
All 8 different pressure scenarios that can be distinguished for gas phase detonations in pipes were addressed by the experiments, even the extremely rare case of having the deflagration to detonation transition occurring within about 1 pipe diameter a head of blind flange which yields the largest static equivalent pressure of all scenarios.
By these tests it was possible to (1) validate the predictions of recently developed numerical models for predicting the structural response of the pipe wall and to (2) determine the static equivalent pressure of gas phase detonations in pipes even for those detonative pressure scenarios for which a reliable pressure/space/time profile required as input for the numerical models is at present not yet available. Once the static equivalent pressure is known, the well-established pressure vessel design guidelines, which can only cope with static loads, can be applied for detonation pressure proof pipe design in all those cases where the detonation speed is not close to the propagation speed of the flexural waves in the pipe.
Furthermore, preliminary information was obtained about which of the 8 detonative pressure scenarios only depends on the Chapman-Jouguet pressure ratio of the involved mixture and which scenarios will also depend on other characteristic parameters of the involved mixture (difference between initial temperature and auto ignition temperature, ignition delay time).
