What is the necessity of using an internal floating roof combined with a vent valve?

Above the floating liquid surface of the internal floating roof, it rises and falls with the liquid level; thus, a relatively enclosed moving gas phase space is formed between the liquid surface and the floating roof, effectively preventing losses caused by large and small breathing effects. Furthermore, it significantly reduces the oil and gas concentration in the space between the floating roof and the tank top; the concentration of gases above the floating trays of tanks with internal floating roofs for various materials is within completely acceptable ranges. Therefore, it is unnecessary to install a breather valve on an internal floating roof tank.

A breathing valve is similar to a one-way check valve; it allows air to be exhaled outward but not inhaled inward. When the pressure inside the system rises, gas is released outward through the breathing valve, thereby maintaining a constant pressure in the system. It is generally used on storage tanks at normal or low pressure. “The correctness of this view needs further verification. --qwer123” This post was last edited by qwer123 on 2008-5-2 23:35 ]

As the name implies, a breathing valve allows both exhalation and inhalation; it is not a one-way valve for preventing flow in only one direction, so please don’t be misled

On the 3rd floor, the emergency relief valve might have been mistaken for a breather valve

The information on floor 3 is highly misleading! In my opinion, internal floating roof tanks do not require breather valves; it seems I have never seen any need for them.

The title is a bit large; it needs to be chosen based on the actual situation, and in some cases it is necessary to select it. But it was added; one can’t be wrong about that. In principle, internal floating roof tanks do not require breather valves.

In the future, environmental regulations will require the use of internal floating roofs combined with breather valves; this can effectively reduce the evaporation of materials and also help protect the environment.

A floating roof tank is not a fixed-roof tank; it requires neither a breather valve nor a safety valve.

Have you seen floating roof tanks upstairs? How is it possible that an external floating roof doesn’t have a breathing valve? Yet another attempt to mislead people. The correctness of this view needs further verification. Personally, I think whether a floating roof tank needs a vent valve depends on the circumstances; some tanks require one while others do not. The key is to understand the purpose and function of installing a vent valve. The function of breathing is to maintain pressure balance in the tank and reduce oil and gas losses to a certain extent (mainly through minor breathing). If the requirements regarding oil and gas losses are not very strict, it is not necessary to install such a system when using an external floating roof; otherwise, it is necessary to install it. --qwer123” This post was last edited by qwer123 on 2008-5-3 00:02 ]

For a floating roof tank with a nitrogen seal, a vent valve should be installed; otherwise, what is used to balance the pressure inside and outside the oil tank? In the case of a simple floating roof tank, an air vent is usually provided at the top of the tank wall, so there is no need to install a vent valve

Seeing the intense discussions, I want to join in too. Have you all seen internal floating roof tanks with breather valves? Is it sufficient to make a few openings around the floating roof?

I’ve never seen a floating roof tank equipped with a vent valve Isn’t the function of a breather valve to regulate the pressure in the oil-gas space? Why is it such a complicated discussion? The floating roof of a floating roof tank comes into direct contact with the oil surface; therefore, there is no space for oil to accumulate. So what’s the need for it? Except for nitrogen sealing!

Breath valves can help protect the environment; please explain their principle! Personally, I think a breathing valve cannot serve this purpose. “Comment: The function of a breathing valve is to keep the large tank operating under a slight positive or negative pressure, which helps to reduce oil and gas losses from the tank to some extent. Generally, a smaller breathing valve results in less loss, while a larger one has less of an impact; in this sense, it can play a role in environmental protection – mainly by reducing losses through a smaller breathing valve – but the effect is not significant. At present, what can truly help protect the environment is operating large tanks under pressure (slightly positive pressure) to recover and reuse oil and gas, a practice that is used in the large tanks at oilfield combined stations. --qwer123” This post was last edited by qwer123 on 2008-5-2 23:45 ]

Internal floating roof tanks all have openings above the tank wall (or on the roof of the tank), so there is no need to install a vent valve.

Our factory uses external floating roof tanks with capacities of 50,000 cubic meters and 100,000 cubic meters. Perhaps I didn’t observe carefully enough, but I certainly have no intention of arguing with you. Learning from you*. :handshake

Another point is that our company’s external floating roofs do not have safety valves; if the floating disk gets stuck, the vent valve should be able to provide some level of protection. I’m not sure if this aspect is also taken into account in the design. I’ll need to ask the original designers about it another time.

Should answers that contain fundamental errors be deleted by the moderators or clearly marked? Otherwise, could it mislead newcomers?

For detailed information, refer to \"Crude Oil Pipeline Transportation Technology\", published by Sinopec Press and compiled by Huang Chunfang from the China Petroleum Pipeline Institute. Here is a quote. It seems like the image can’t be attached. IV. Special Accessories for Internal Floating Roof Tanks
The accessories that distinguish internal floating roof tanks from ordinary dome-shaped tanks are as follows: (1) Vent holes. Figure 14-3-28 shows the vent valve on the tank top, while Figure 14-3-29 shows the vent holes on the tank wall. 1 – Welded flange; 2 – Connection pipe; 3 – Cover; 1 – Stainless steel mesh and clamping strip; 2, 4 – Tank wall; 4 – Stainless steel mesh; 3 – Opening in the tank wall; 5 – Tank top; 6 – Cover plate. In internal floating roof tanks, the oil level is completely covered by the internal floating disk, so there is no need to install mechanical breather valves or hydraulic safety valves on the tank top. However, in practice, if the seals at various connections become slightly loose, oil and gas can still leak out. When the floating disk descends, oil vapor can accumulate in the space between the floating disk and the dome, due to factors such as the evaporation of the oil film adhering to the tank wall. To dilute and disperse these oil and gas gases in a timely manner and prevent the concentration of oil vapors from reaching the flammable or explosive limits, ventilation holes are provided on the top of the tank and around its walls. The vent hole on the tank top is shown in Figure 14-3-28. Installed in the middle of the vault, with a diameter of not less than 250 mm, and covered with wire mesh and a rain cover around it and on top. Vessel wall vent holes, installed around the top of the vessel wall. The circumferential spacing between each orifice should not exceed 10 m, and at least 4 orifices should be provided per oil tank. The total opening area is required to be at least 0.06% of the tank diameter. Metal wire guards are installed at the inlet and outlet of the ventilation holes. Figure 14-3-29 shows a schematic diagram of the installation location of the tank wall vent holes. The vent holes on the tank wall also serve as an overflow function when the oil level is too high and the automatic alarm system fails. The ventilation holes in the tank wall should be arranged in a symmetrical pair to ensure adequate air circulation, thereby minimizing the concentration of oil vapors in the space between the tank’s floating deck and the roof.