Questions regarding the design of the concentrated sulfuric acid tank area
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The design currently includes two 1000 M3 storage tanks for 98% sulfuric acid, with dimensions of Φ11X11m. In accordance with the Code for Fire Protection Design of Petrochemical Enterprises, the effective volume within the cofferdam shall be no less than the volume that could leak from the largest storage tank in the tank farm; therefore, a cofferdam with dimensions of 44*24*1.3 m (in height) has been designed. I would appreciate your advice: Can pumps such as feed pumps and discharge pumps for concentrated sulfuric acid be installed inside the cofferdam? Refer to the \"Code for Fire Protection Design of Petrochemical Enterprises\": 5.3.5 The dedicated pump area for tank assemblies should be located outside the fire dike, and the fire separation distance from the storage tanks shall comply with the following requirements: 1. It should be no less than 15 m from Class A storage tanks ； 2. The distance from such tanks should be no less than 12 m for Class A/B fixed-roof storage tanks, and no less than 10 m for Class A/B fixed-roof storage tanks with a capacity of 500 m3 or less ； 3. The distance from floating roof and internal floating roof storage tanks, as well as Class C-A fixed-roof storage tanks, should be no less than 10 m; the distance from internal floating roof storage tanks and Class C-A fixed-roof storage tanks with a capacity of 500 m3 or less should be no less than 8 m. 5.3.6 When the dedicated pump for combustible liquid storage tanks other than Class A, Group A is installed separately, it shall be placed outside the fire dike, with no requirement for a fire separation distance from the combustible liquid storage tanks. How should this be understood? Is concentrated sulfuric acid classified as Category B? Is it arranged at a distance of at least 12m from the storage tank according to 5.3.5? Should it still be according to 5.3.6, as long as it’s outside the cofferdam? Or since concentrated sulfuric acid is non-flammable, can it be placed inside the cofferdam?
Concentrated sulfuric acid belongs to Category D or E, while fuming sulfuric acid belongs to Category B. Therefore, a fire dike is not necessary in the tank area; a protective dike is sufficient. A cofferdam should be installed around the pump area itself.
After checking, this is quite controversial; one theory suggests that 98% sulfuric acid falls into Category B, on the grounds that it is a strong oxidizing agent that does not belong to Category A. Just because it is explicitly stipulated that nicotinic acid belongs to Category B, it does not mean that 98% concentrated sulfuric acid is not of Category B.
Pumps cannot be installed inside the cofferdam.
There are also requirements regarding the distance between the tank and the cofferdam; it depends on how high the foundation of your tank is built
The effective volume within the cofferdam must be no less than the volume that would leak from the largest single storage tank in the tank farm: it is half of that volume, and this is clearly specified in Japan’s fire safety laws. Domestic pumps are installed inside the cofferdam
Yes, according to the specifications, the horizontal distance from the foundation line on the inside of the fire dike to the outer wall of the vertical storage tank should not be less than half of the tank wall height. This design achieves that. Could you please explain the specific relationship regarding the height of the storage tank foundation?
Let me explain: The fire hazard category of concentrated sulfuric acid was indeed classified as Category B in the past, but designs in recent years have taken Category D or E into account. These projects also follow the \"three simultaneities\" procedure, so there is practical evidence to support this. Similarly, the installation of cofferdams in the pump area and protective dikes in the tank area is aimed at addressing minor leaks from flanges and valves, thereby preventing the spread of liquid.