In the event of an explosion through a high pressure gas pipe, is there a way to vent the pressure wave, in order to protect downstream objects? The mechanism must be faster than sound; pressure relief valves and even rupture discs are actually too slow and will not respond to such a "fast" pressure wave.
They are called blast valves. You need a delay loop in the pipe so the trigger can get ahead of the shock wave. Our interest was in closing off ventilation air conduits before the nuclear weapon's overpressure could penetrate the site.
See the pipe loops over the Launch Control Equipment Building? Those are the delay loops for ventilation air.
I will propose a possible answer here. If you have an optical sensor in the pipe which detects the flash of the explosion, it may be possible to use that flash signal to open a pressure dump valve or a series of such valves prior to the arrival of the pressure wave at the downstream location you wish to protect. this solution uses the idea that the electric signal can be transmitted to the valve faster than the sonic velocity inside the pipe but it also requires a dump valve which can be opened very quickly. Ratchet freak may be right; dissipating the energy of the explosion may be the better answer, especially since it does not require instrumentation and fast-acting valves.