Problem of float disc damage during ball passing operations in gasoline pipelines
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This post was last edited by mryu on 2019-1-23 at 10:35. Seeking help from forum friends and experts: As a third-party tank storage company, in order to prevent mixing of fluids of different qualities, it is necessary to use pigging operations – that is, to send balls through the pipeline – starting from the launcher at the port after each ship operation. A three-bowl pig is used; the storage tank is a 10,000-liter floating roof tank. The pipeline length is approximately 1,200 meters, with a diameter of DN500. Nitrogen is used to push the balls through the pipeline, with the pressure kept at less than 0.25 Mpa. The liquid level in the tank is not fixed – it should not be lower than 3 meters nor higher than a certain maximum level. The tank features a double-sealing system. The problem is that when the dock sends balls to the storage area, it occasionally causes damage to the floating pads. Analysis determined that excessive air (nitrogen) intake into the tank caused damage to the floating disk. Help: In this operation method, how can air from the outside be prevented from entering the storage tank, or how can damage to the floating disk be avoided? Thank you
We rely on diffusers, and we also need to carefully control the pressure; so far, there are no problems. It is best to have a dedicated wire-cleaning tank. . . Having to face this hurdle is indeed a major risk that one encounters frequently. . .
Well, we have them too, but they weren’t used in this assignment; other imported ones were used instead. In fact, the diffuser inside the tank should serve a certain purpose, right? But it’s still necessary to control the flow of gas into the tank in order to avoid damage to the floating disk. How can this be controlled? It seems that everyone has to rely on their experience to handle this
It should be fine to stop breathing immediately when the ball arrives; after all, the float disk has a certain degree of strength and flexibility, unless its quality is poor. . .
Friend, you’re right. The problem is that it’s not possible to guarantee that there’s no air in the pipelines during this process; oil and gas will always end up entering the tank. What can be done about this?
This problem is likely quite common; it is recommended to replace your receiver drum with a pigging valve, which will prevent gas from entering the tank. Before making the replacement, it is essential to control the amount of nitrogen entering the tank. Once the ball is in place, the valve behind the ball collection cylinder must be closed promptly. Additionally, care must be taken to ensure that the speed at which the ball is moved is not too fast, as this could lead to air leakage; rapid movement would cause the leaked air to enter the tank quickly, and the rising gas would stir the liquid, resulting in excessive movement of the floating disk on the surface of the liquid and potential damage to it. It is particularly important to note that the anti-rotation wire rope of the floating disk must be strong, and the spring underneath must not come unhooked; otherwise, when the liquid moves, the floating disk will move freely without any restraint, which could lead to its tearing. These are just my personal opinions, for reference only.
Everyone upstairs has said great things; I’d like to offer a different perspective. If the frequency of ball passing and line sweeping is high, one can start by using a float disc of higher strength, such as one made of stainless steel. Even floating pads made of the same material can have significant differences in strength depending on their structure. Personal opinion, for reference only.
Thank you for the very professional guidance. I’ve also communicated with the manufacturers of floating trays. What was mentioned regarding on-site construction is quite representative: in the absence of a buffer tank or a tank without a floating tray specifically designed for ball passing, introducing air into such a tank to pass balls through it will eventually lead to damage to the floating tray. Although this might be an extreme case, it seems to be a common problem. The sealing of the balls is also crucial. In my opinion, it’s important to control the amount of air entering the storage tank as well. Previously, the pigging valves also got damaged; after installing diffusers, the time between failures increased somewhat. I think it’s really important to figure out how to properly control the amount of air that enters the tank
I’ve talked to companies in the surrounding area; one foreign company uses stainless steel products. After communicating with them, I found that damage to the floating discs occurs frequently, which is also a major problem for them
Another factor is that the receiving chamber should be as far away from the receiving tank as possible. This will make the air intake much smoother
It’s certainly good that the receiving chamber is far from the reception tank; however, it’s also a problem that the material in the remaining sections of the pipeline cannot reach the storage tank