Discussion on the floating roof sealing types and nitrogen sealing in storage tanks
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For large internal floating roof storage tanks used to store highly toxic substances such as acrylonitrile: 1. Is a secondary seal necessary for the internal floating roof when a nitrogen blanket is in place? Are there any specific standards to guide this? 2. According to the latest draft of the \"Standards for Controlling Unorganized Emissions of Volatile Organic Compounds\" solicited by the Ministry of Environmental Protection: 6.2 Storage tanks for volatile organic liquids 6.2.1 For storage tanks holding organic liquids whose actual vapor pressure is ≥76.6 kPa, and where the volume of a single tank is ≥50 m3, or where the total volume of all tanks storing the same substance in the same location is ≥500 m3, one of the following measures must be adopted: a) Use pressure tanks; b) If non-pressure tanks are used, an exhaust gas collection system must be installed to direct the exhaust gases to VOCs treatment facilities; c) Other equivalent measures. 6.2.2 For stored materials with a true vapor pressure ≥ 2.8 kPa but
Can liquid inlay be understood as a pouch-type seal?
I’ll share what I’ve downloaded from the internet; it’s up to you to determine whether it’s accurate
This post was last edited by Star of Safety on 2017-9-16 at 16:19; it seems that a nitrogen seal is better.
The internal floating roof sealing method and nitrogen sealing are based on different principles: the former is intended to prevent volatile leaks, while the latter focuses on ensuring safety; moreover, the latter requires an oil and gas recovery system.
When the standards were first established, many people thought that the liquid embedding method referred to the type using a fluid filling tube. If that was the case, then higher requirements would apply to the internal floating disk design. Later, I consulted the Ministry of Environmental Protection regarding whether the term \"liquid embedding\" in the \"Standards for Controlling Unorganized Emissions of Volatile Organic Compounds\" actually referred only to the method using a fluid filling tube. According to the experts responsible for interpreting these standards, it might be a translation issue from the time the standards were drafted; as long as there is effective sealing, it’s sufficient. However, there was no place where an definition of efficient sealing was provided; therefore, we found the corresponding American standard, and from that standard we returned to API650. From this, it can be inferred that the liquid-filled sealing type mentioned here corresponds to the fluid-contact peripheral sealing described in API650. The original bladder-type sealing is also acceptable, as long as the lower part of the seal makes contact with the fluid. Later, I met the editor-in-chief of GB50341 and asked the expert about this issue, and the expert gave the same answer; they handle it in this way in their actual practice as well. Moreover, according to experts, it is possible that steel discs will be used for all internal floating discs in the future.
I have a question for you. Currently, the company is carrying out VOCs control measures and needs to upgrade the sealing of its storage tanks to make them more efficient. However, all of the company’s existing storage tanks use bladder seals (with sponge filled inside rubber). Do these constitute liquid-filled seals? Is it possible to avoid modifications, since no relevant standards are available indicating that the pouch seal belongs to the liquid-infiltration type?
At present, when dealing with some refineries, I follow the principle that \"as long as the sealed lower part is in contact with the liquid storage, it’s sufficient.\" If a liquid-filled sealing method is used, the cost is too high
Whether the Environmental Protection Agency approves it is another matter