What are the structural features of external floating roof tanks?

Sep 22, 2025

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Structural features of the external floating roof tank

 

The upper part of the external floating roof tank is open, and the top cover is not arranged on the other. The roof of floating roof is in direct contact with the atmosphere. From the point of view of the structure design of the oil tank, the external floating roof tank is different from the other tanks. It is a problem that how to solve the problem of the stability of the tank wall under the action of wind load. In order to increase the stiffness of tank wall, in addition to the panel on the edge of a wrapping angle, away from the plate margin of about 1m and a wind ring. Wind ring is assembled by steel plate and steel combined section structure, its shape is round, can also be a polygon. For large oil tank, set one or more laps to ring in wind ring below, to prevent the tank wall wind ring following instability.

 

Accessory features of the external floating roof tank

 

In order to make it convenient for the management and maintenance of floating roof tank, the following is some accessories that are different from the attachment of the fixed roof tank.

 

Central drainage pipe. Floating roof of external floating roof tank directly exposure to the atmosphere, fall in the floating on top of rain and snow was not removed timely may cause floating roof sank. The central drainage pipe is arranged in order to discharge the rainwater collected on the floating roof in time. The upper is connected with central sump, the lower is connected to the outside of the tank drain valve. Floating on the top of the water is concentrated in the central sump, exhaust to the outside of a tank without oil pollution through the drainage tube. The central drainage pipe is composed of several sections of D IV 100mm which is immersed in the oil. Between the pipe and the pipe section is connected with a movable joint, with floating roof height of straight and bending, so called drainage folding tube. According to the size of the tank diameter, each tank can be provided with l~3 root drainage folding pipe.

 

Top of turn escalator is hanged on platform, so that it can be rotated around the hinge installed in the vicinity of the platform. The lower end of the float can be moved along the track on the floating roof with the floating roof lifting. The operator can work from the floating ladder to the floating roof. When the floating roof falls to the lowest position, the elevation of the rotating staircase shall be no more than 600.

 

There are 18 isolation of choking hole floating manhole, and 1 single disc manhole. The staff can get into the cabin to check for leaks through the manhole floating, or get into the tank by single disc manhole.

 

The valve is arranged on the floating roof, path diameter is 300mm. The effect is that the air in the tank is discharged when the floating roof is not floating to advance oil, or when the floating roof is supported on the oil tank to continue oil, the air is filled to the tank to prevent the vacuum from the top of the tank.

 

Emergency drain port is a backup safety device of drainage pipe. If the drainage fold tube failure, or when the floating roof rainwater accumulated in the upper, drainage tube cannot discharge in time, when the stockpile rainwater exceeds a certain height, can from emergency drainage tube row within the tank, lest floating boat sank.

 

The floating roof pillar is provided with 53 pipe support, and the circumferential distribution is arranged on the lower part of the floating roof, and the height of the floating roof upright column is generally adjustable in the range of 1.2~1.8m. On the one hand, this is to avoid the lower surface of the floating ship and the tank of the heating coil and other accessories collision. On the other hand is to maintenance support floating roof supporting height adjusted to 18m), in order to make the floating roof down to the lowest position with plenty of room for maintenance and cleaning.

 

There are totally two disc edges and the edge vent, which are respectively located on the edge of the single plate and the floating boat. The effect is to discharge the excess oil and gas from the bottom of the tank and the air filled with oil. Opening pressure is 12mm water column.

The operator measure the oil in the top of tank, at the same time, the floating roof plays a guiding role.

 

Contact for Tank Specs

 

In addition to storage tanks, GNEE also offers more high-quality products, such as shell-and-tube heat exchangers, copper heat exchangers, titanium heat exchangers, heaters, chlorine coolers, high-pressure reactors, LPG storage tanks, cryogenic storage tanks, VPSA oxygen generators, etc. If you are interested in the above products or other products, please feel free to send an email to global@gneesteels.com, and our professional team will be happy to answer your questions.

 

GNEE CRYOGENIC LIQUID OXYGEN STORAGE TANK

TYPE

VOLUME
(M3)

SPECIFICATION

DESIGN CODE

Inside shell

Outside Shell

Vertical

5

φ1400X3672X6

φ1900X5115X8

ASME/PED

Vertical

φ1400X3672X8

φ1900X5115X8

ASME/PED

Vertical

10

φ1700X4705X6

φ2200X6035X8

ASME/PED

Vertical

φ1700X4705X10

φ2200X6035X8

ASME/PED

Vertical

15

φ1800X6214X6

φ2300X7730X8

ASME/PED

Vertical

φ1800X6214X11

φ2300X7730X8

ASME/PED

Vertical

20

φ2100X6146X7

φ2600X7655X8

ASME/PED

Vertical

φ2100X6146X12

φ2600X7655X8

ASME/PED

Vertical

30

φ2100X9046X8

φ2600X10605X8

ASME/PED

Vertical

φ2100X9046X14

φ2600X10605X8

ASME/PED

Vertical

50

φ2600X9885X9

φ3200X11670X10

ASME/PED

Vertical

φ2600X9885X16

φ3200X11670X10

ASME/PED

Vertical

100

φ3000X14670X11

φ3600X16550X14

ASME/PED

Vertical

φ3000X14670X20

φ3600X16550X14

ASME/PED

Vertical

150

φ3200X19308X12

φ3800X22000X14

ASME/PED

Vertical

200

φ3400X22624X14

φ4000X25300X14

ASME/PED

 

GNEE CRYOGENIC LIQUID OXYGEN STORAGE TANK

TYPE

VOLUME
(M3)

SPECIFICATION

DESIGN CODE

Inside shell

Outside Shell

Horizontal

5

φ1400X3672X6

φ1900X4802X8

ASME/PED

Horizontal

φ1400X3672X8

φ1900X4802X8

ASME/PED

Horizontal

10

φ1700X4705X6

φ2200X5980X8

ASME/PED

Horizontal

φ1700X4705X10

φ2200X7210X8

ASME/PED

Horizontal

15

φ1900X5626X6

φ2400X7210X8

ASME/PED

Horizontal

φ1900X5626X11

φ2400X7210X8

ASME/PED

Horizontal

20

φ2100X6146X7

φ2600X7310X8

ASME/PED

Horizontal

φ2100X6146X12

φ2600X7310X8

ASME/PED

Horizontal

30

φ2100X9046X8

φ2600X10200X8

ASME/PED

Horizontal

φ2100X9046X12

φ2600X10300X8

ASME/PED

Horizontal

50

φ2600X9885X8

φ3200X11400X10

ASME/PED

Horizontal

φ2600X9885X14

φ3200X11275X10

ASME/PED

Horizontal

100

φ3000X14670X10

φ3600X16350X12

ASME/PED

Horizontal

φ3000X14670X16

φ3600X16900X12

ASME/PED

Horizontal

150

φ3200X19308X10

φ3800X20700X12

ASME/PED

Horizontal

200

φ3400X22624X11

φ4000X24500X12

ASME/PED

 

external floating roof tank

external floating roof tank

external floating roof tank

external floating roof tank