A modular subsea fluid storage unit has a variable-volume inner tank having a rigid top panel and a peripheral wall that is flexible by virtue of concertina formation. The peripheral wall is extensible and retractable vertically while the horizontal width of the tank remains substantially unchanged. A side wall of a lower housing part surrounds and is spaced horizontally from the peripheral wall of the inner tank to define a floodable gap between the peripheral wall and the side wall that surrounds the tank. An upper housing part extends over and is vertically spaced from the top panel of the inner tank and overlaps the side wall to enclose the inner tank. The floodable gap and the upper housing part enhance thermal insulation and trap any fluids that may leak from the inner tank.

Systems, methods and apparatuses for inspecting a tank containing a flammable fluid are provided. A vehicle configured to inspect the tank can include a propeller, a battery, a control unit, an inspection device, and a ranging device. The battery provides power to the propeller, the control unit, the inspection device, and the ranging device. The control unit generates a map of the tank. The control unit determines a first position of the vehicle on the map of the tank. The propeller moves the vehicle through the flammable fluid in the tank. The inspection device determines a quality metric of a portion of the tank. The control unit causes the propeller to move the vehicle from the first position to a second position within the tank. The control unit determines the quality metric for the portion of the tank at the second position within the tank, and stores the quality metric.

Systems, methods and apparatuses for inspecting a tank containing a flammable fluid are provided. A vehicle configured to inspect the tank can include a propeller, a battery, a control unit, an inspection device, and a ranging device. The battery provides power to the propeller, the control unit, the inspection device, and the ranging device. The control unit generates a map of the tank. The control unit determines a first position of the vehicle on the map of the tank. The propeller moves the vehicle through the flammable fluid in the tank. The inspection device determines a quality metric of a portion of the tank. The control unit causes the propeller to move the vehicle from the first position to a second position within the tank. The control unit determines the quality metric for the portion of the tank at the second position within the tank, and stores the quality metric.

A composite structure of a cargo body and a method of making the same are disclosed. The composite structure includes at least one electrical grid embedded within fiber-reinforced polymer (FRP) layers. The embedded electrical grid includes a plurality of conductive fibers and a plurality of insulating fibers integrated into a polymer matrix of the FRP layers. The embedded electrical grid may be used for power distribution, structural strengthening and stiffness, and/or puncture detection.

A high-performance seafloor flexible oil storage system, solving the existing problems of high storage cost and difficult maintenance of crude oil in offshore oilfields, comprises, sequentially connected, an oil-water separator, a pressure pump, and an input riser extending downward below the sealevel; and a pipeline and multiple flexible oil storage tanks having the same structure with each communicated therewith through a control valve are arranged below the sealevel. One end of the pipeline is communicated with the input riser through a blocking valve and an input valve, and the other end further sequentially connected with an outlet booster pump, an output valve, and an output riser extending upwards above the sealevel and connected to a tanker through a cooler and an output pump. The flexible oil storage tank has a concrete counterweight connected thereunder for fixing it to a seabed. The system has simple structure, convenient maintenance and good practicability.

A tightness-gauging device and a meter for gauging a pressure's sustainability pt for a pressure vessel or system are provided. A pressure is produced against the test fluid inside a piston cylinder communicated with the tested vessel or system by a fixed-pressure supplying assembly including a weight, a piston, and a piston cylinder successively arranged coaxially and vertically. An equation R.sub.L=pt/C is used to represent the tightness of the pressure vessel or system. The equation pt=p(p−0.5Δp)Δt/Δp is used in the meter for gauging the pressure's sustainability pt to express the pressure's sustainability, where p is the fixed test pressure, t is the elapsed time for the fluid to leak completely, C is the cubage of the pressure vessel or system, Δp is the drop value of the pressure, and Δt is the elapsed time for the pressure to descend from p to (p−Δp) caused by the leakage.

A tightness-gauging device and a meter for gauging a pressure's sustainability pt for a pressure vessel or system are provided. A pressure is produced against the test fluid inside a piston cylinder communicated with the tested vessel or system by a fixed-pressure supplying assembly including a weight, a piston, and a piston cylinder successively arranged coaxially and vertically. An equation R.sub.L=pt/C is used to represent the tightness of the pressure vessel or system. The equation pt=p(p−0.5Δp)Δt/Δp is used in the meter for gauging the pressure's sustainability pt to express the pressure's sustainability, where p is the fixed test pressure, t is the elapsed time for the fluid to leak completely, C is the cubage of the pressure vessel or system, Δp is the drop value of the pressure, and Δt is the elapsed time for the pressure to descend from p to (p−Δp) caused by the leakage.

A method for sorting unsystematic environment risk of underground storage tank systems includes: generating an unsystematic environmental site assessment priority list for the underground storage tank systems using a risk weight assessment module based on facility level factor data and operational status factor data of each underground storage tank system; obtaining an actual soil gas detection data for each underground storage tank system after conducting an environmental site assessment on the priority list; and generating an investigation list according to the contamination potential assessment result of each underground storage tank system using a contamination potential assessment module based on the actual soil gas detection data as a basis for subsequent investigation and regulation on the underground storage tank systems.

A method for sorting unsystematic environment risk of underground storage tank systems includes: generating an unsystematic environmental site assessment priority list for the underground storage tank systems using a risk weight assessment module based on facility level factor data and operational status factor data of each underground storage tank system; obtaining an actual soil gas detection data for each underground storage tank system after conducting an environmental site assessment on the priority list; and generating an investigation list according to the contamination potential assessment result of each underground storage tank system using a contamination potential assessment module based on the actual soil gas detection data as a basis for subsequent investigation and regulation on the underground storage tank systems.

Systems, methods and apparatuses for inspecting a tank containing a flammable fluid are provided. The method includes opening a lid of a tank containing the flammable fluid. The method includes connecting a cable to a vehicle that includes a battery and a control unit. The method includes lowering, via the cable and through an opening of the tank, the vehicle through a vapor barrier within the tank and on top of the flammable fluid. The method includes disengaging the cable from the vehicle subsequent to the vehicle contacting a floor of the tank. The method includes removing the cable from the tank. The method includes performing, via the control unit of the vehicle, a tank inspection process under battery power, the tank inspection process comprising generating a map of the tank and determining a quality metric for a portion of the tank corresponding to a location on the generated map.