Storage tank, Category D and E, liquid caustic soda
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I would like to ask the experienced colleagues here: I’m working on a technical renovation project for a tank farm. To meet the requirement of maintaining a 7-meter-wide fire lane between tank groups, we also need to ensure an appropriate distance between the storage tanks and the fire dike. May I ask whether, for Class D and E storage tanks—such as those used for liquid caustic soda—the distance from the tank base to the inner edge of the fire dike should also be greater than half the height of the tank? I’d appreciate any guidance on this matter
There is no such requirement for storage tanks classified under Category D and E. GB50016 hardly mentions anything about storage tanks of these categories at all. According to Article 4.2.5 of GB50016, for above-ground or semi-underground storage tanks or groups of storage tanks used for storing liquids of Categories A, B, and C, non-combustible fire dikes must be constructed around them. The installation of fire dikes shall comply with the following provisions: 3 The horizontal distance from the inner base line of the fire dike to the outer wall of a vertical storage tank shall not be less than half the height of the tank wall. The horizontal distance from the inner toe of the fire dike to the horizontal storage tank shall not be less than 3 m ； This requirement primarily applies to storage tanks of categories A, B, and C; no requirements are stipulated for those in categories D and E. Additionally, the Design Code for Fire Dikes in Storage Tank Areas (GB50351-2014) mainly outlines design requirements for fire dikes surrounding oil tanks and natural gas tanks. Therefore, the fire dikes for category D and E tanks can be designed based on actual circumstances—it is sufficient that they can contain and manage any liquid that might leak out following a tank rupture. Since category D and E tanks operate under normal pressure, the distance between the fire dike wall and the tank wall must be such that any leaked liquid will be propelled outward due to the pressure exerted by the liquid above it; this distance can be calculated using Bernoulli’s equation. In practice, however, this level of complexity isn’t necessary. In several tank farm renovation projects I’ve worked on, we simply utilized semi-underground tanks to address this issue; given their underground location, even if a leak occurs, the liquid won’t be able to escape beyond the fire dike.
Take a look at standards related to general layout, such as GB 50984; don’t just focus on fire protection codes all the time