Floating Roof Tank Vent Design

The roof rises and falls with the liquid level in the tank.

Floating roof tank vent design.

An external floating roof tank is a storage tank commonly used to store large quantities of petroleum products such as crude oil or condensate. 2 16 failure mode due to seismic effects on floating roof tank 34 2 17 fitting design and requirement 36 2 18 typical fitting and accessories for floating roof 37. Today controlled gas venting in to the atmosphere is becoming more and more important due to environmental regulations. Floating roof tank allow the explosive gases in petroleum tanks to vent to atmosphere in a safe way.

For normal venting api 650 g 8 3 and h 6 2 specifies vents in the fixed roof tank shell and internal floating roof. The vents in the floating roof protect the roof and rim seal and accommodate liquid movement and thermal breathing. The floating roofs can be either external i e with open top tanks or internal i e inside fixed roof tanks. For a tank with a fixed roof and internal floating roof but without a gas blanket.

Instead the cfrt is equipped with a pressure vacuum pv vent and may even include a gas blanketing system such as that used with fixed roof tanks these tanks are designed as in appendix c of the api standard 650. It consists of an open topped cylindrical steel shell equipped with a roof that floats on the surface of the stored liquid. Vii 2 18 1 roof seal system 37 2 18 2 support leg 38 2 18 3 roof drain system 39 2 18 4 vent bleeder vents 43 2 18 5 centering and anti rotation device 44. Floating roofs have been designed and used for more than a century.