The vapor tight tanks are all designed to hold a pressure of 16 oz/sq.in pressure which is considered a positive pressure atmospheric tank. The pressure relief systems supplied by DHI is typically set at 10 oz/sq.in venting to atmosphere. The tanks are to be normally vented via a 4” line to a larger diameter flare header flowing to a combustion flare/burner or atmospheric diffuser, in some case vapor recovery equipment may be employed to further reduce emissions.
This vent flowline needs to be be equipped with devices to prevent any flame blowback into the tanks caused by any pressure under balance (flame arrest device) by tank fluid evacuation or any other activity.
The tanks are equipped with access man ways that must be kept closed at all times when in use. The “Green Completion” tanks provide ways to minimize on site emissions to the lowest possible level.