Hidden dangers of fire dike in the hottest storage

2022-08-14
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Hidden dangers and Countermeasures of fire dike in storage tank area in the process of preventing the diffusion of dangerous liquids

I. hidden dangers of fire dike

(I) it is difficult to prevent serious oil leakage accidents. Article 3.2.4 of the Code stipulates that the effective capacity in the fire dike shall meet the following requirements: 1. The fixed roof oil tank shall not be less than the capacity of the largest oil tank in the oil tank group; 2. The floating roof oil tank or inner floating roof oil tank shall not be less than half of the maximum oil tank capacity in the oil tank group; 3 when the fixed roof oil tank and the floating roof oil tank or the inner floating roof oil tank are arranged in the same group, the larger of the calculated values specified in paragraphs 1 and 2 of this article shall be taken; 4. The effective volume in the fire dike of the earth covered oil tank is the same as that in paragraphs 1, 2 and 3 of this article, but the capacity of the oil tank adjusted through the structural components shall be calculated according to the capacity of its part above the ground. In this case, when the oil tank suffers serious damage (such as tearing of the tank bottom), a large number of oil products 4 The tensile test (strength indicators include: spring modulus, specified non proportional elongation stress, tensile strength, maximum force, etc.) leaks into the fire dike and may be accompanied by combustion. At this time, the dike will lose its function, and the oil tank in the same tank group is very easy to explode due to direct baking, which will further increase the leakage; At the same time, for the floating roof tank group, since the effective volume of the fire dike is only half of the largest tank capacity in the tank group, it is impossible to prevent the worst accidents such as the tearing of the bottom of the largest tank

(II) because the oil tank fire is difficult to extinguish, resulting in long combustion duration; Moreover, there are precedents of tank damage, oil leakage and combustion. Therefore, in order to put out oil tank fires, it is often necessary to invest extraordinary fire-fighting forces, resulting in the fire-fighting water consumption exceeding several times or even dozens of times the design consumption. If these water is stored in the fire dike, it will inevitably cause the oil level in the dike to rise, which is likely to cause the oil fire to spread outside the fire dike

(III) when there is a fire in the storage tank area, the temperature of the fire site can reach more than 1000 ℃. Brick, block fire dike and rubble fire dike are subject to this high-temperature flame baking and burning, which is very prone to distortion, cracking and damage; The concrete fire dike is also unable to resist the baking of this high temperature. At the same time, when the fire water is sprayed on the fire dike, it is also easy to cause the fire dike rupture accident

II. Corresponding measures to eliminate hidden dangers

(I) we are ashamed to pay attention to the role of fire dike, and build fire dike in strict accordance with the relevant provisions of the code. The existing fire dike should be analyzed whether it can meet the requirements, and the non-compliance should be corrected immediately

(II) increase the effective volume of the fire dike

1. Appropriately increase the height of the fire dike without violating relevant regulations. The reason why the specification restricts the outer height of the fire dike is that too high a fire dike will affect the observation of the fire and make it difficult to extinguish the fire. Properly raising the height of the fire dike without violating the relevant regulations is one of the methods to solve the problem of insufficient effective volume of the fire dike

2. When terrain conditions permit, the effective volume of the fire dike should be increased by using the way that the floor in the storage tank group is lower than the floor or road outside the dike. This can not only ensure that the inner height of the fire dike meets the relevant requirements, but also be consistent with article 3.2.9 of the code, "the design ground inside the fire dike of the oil tank group should be lower than the fire road pavement or ground outside the dike". If the designed floor in the fire dike is higher than the fire road pavement or ground outside the dike, the outer dike height of the fire dike will be increased, so that the design section of the fire dike will be increased

the above two methods of expanding the effective volume of fire dike are interrelated with our strategic focus on the development of high-quality plastic products. They should be analyzed according to the specific situation, taking into account the safety and economic requirements, and should be comprehensively considered and used when necessary