Atmospheric pressure storage tank rupture discs and emergency relief manholes
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Dear sea friends, our company has installed rupture discs in front of the emergency relief manholes on some of its storage tanks. What was the reasoning behind this design choice? Are there any relevant standards specifying whether a rupture disc is required or not?
What medium is being stored, or are there severe pressure fluctuations?
It mainly depends on the medium in the storage tank; for safety reasons, emergency pressure relief is possible in case of overpressure
For atmospheric storage tanks of naphtha, there are emergency vent manholes on the outside in case of emergency pressure release; it’s not clear why blast discs are also needed
For emergency pressure relief, there is an emergency release manhole on the outside (of the gravity-type design); it’s not clear why a rupture disc is also needed
For naphtha atmospheric tanks, there is no need to install an additional rupture disc; the pressure relief manhole is used for pressure release in situations where the breather valve is not sufficient. A rupture disc adds yet another layer of pressure control, and it is only after this pressure level is reached that the pressure from the pressure relief manhole is released. The regulations do not require the installation of an additional rupture disc.