7.2　Cavern Tank

7.2.1　Each cavern tank shall be provided with one or more shafts.If composed of two or more caverns，the cavern tank shall have at least two shafts.The shafts should be directly connected to the surface.Their tops may be set up to be open-air，shedded，or in a house，depending on the ambient conditions.If restricted by the topography，they may be set up in the operation tunnels.

7.2.2　Cavern tank shafts shall meet the installation and maintenance requirements of relevant pipelines，pumps，instruments，and cables.

7.2.3　Measures to fix and eliminate liquid impacts shall be taken for pipelines and casings in shafts.

7.2.4　Oil should be stored in the cavern tank in the fixed water table way.

7.2.5　A pump pit shall be set up in the corresponding shaft at the bottom of a cavern，and an at least 0.5m high concrete cofferdam shall be set up around the pump pit.

7.2.6　The loading coefficient of the cavern tank should not be higher than 0.95.

7.2.7　The escaped vapor from the cavern tank shall be disposed of.The emitted gas shall be treated to comply with the standard Emission Standard for Air Pollutants from Oil Storages（GB 20950）.When the cavern tank discharges oil，measures should be taken to prevent any explosive gas from being developed within cavern tank.

7.2.8　Each cavern tank shall be provided with a ventilation pipe with a fire barrier at the outlet.

7.2.9　The operation tunnel shall be provided with at least two passages to the surface.

7.2.10　The space within the operation tunnel shall be sufficient for operation and maintenance.

7.2.11　The pipelines and equipments within the tunnel shall be given a moisture-proof measure.