Vapor Tight Storage & Flowback Tanks
Vapor Tight Flow-Back
The vapor tight tanks are all designed to hold a pressure of 32 oz/sq.in pressure which is considered a positive pressure atmospheric tank. The pressure relief systems supplied by DHI is typically set at 16 oz/sq.in venting to atmosphere.
The tanks are to be normally vented via dual 6” line to a larger diameter flare header (10” recommended) flowing to a combustion flare/burner or for atmospheric dispersion, in some case vapor recovery equipment may be employed to further reduce emissions.
The DHI flare system designed specifically for use with these tanks in the Vapor Tight configuration is designed to minimize back pressure on the tank providing large ID throat to incinerate vented gas safely. The flare is equipped with adequately sized flame arresting devices. The vent flow-line must be equipped with blow back prevention devices if DHI flares are not used.
The tanks come in 2 configurations with and without gas diffusion devices. The units with diffusion equipment are designed to be the receiving tanks, these tanks have additional dead-weight relief devices to prevent any surge from causing risk to tank integrity.
H2S Service Operations
The DHI Vapor Tight System can be configured for H2S (Sour) Service. The tank liners are resistant to H2S and the component upgrades to H2S resistant coated or 316 stainless steel components permits the Vapor Tight configuration to operate without risk of accelerated deterioration and prevent the release of H2S bearing gasses on site and pipe to the flare system for combustion and residual dispersion to atmosphere safely.
Pressure & Vacuum Relief
The purpose of the thief hatch is to work in tandem with the vent valve to minimize the escape of light
ends of crude in the storage tanks by maintaining a blanket pressure in the tanks. A vacuum relief function is also
standard to prevent a suction or draw down event from collapsing the tank. The thief hatch permits access
to the contents of the tank for sampling and level gauging.