Pipeline cleaning issues at docks
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Regarding the pipeline cleaning issue at the dock during loading (referring to ball cleaning before changing the medium), is it better to clean in the direction of the ship or in the direction of the tank farm? How should the medium in the pipeline from the flow meter to the dock be handled, and what issues need to be considered in the design?
It is recommended to use a tank scraper, and before cleaning the tank, set up drainage systems for recovery at the relevant locations.
It is recommended to use a tank purging method, with a bypass line installed for the flow meter, so that the flow meter is not passed through during purging
The flow that passes through the meter is directed onto the ship, which facilitates the measurement of volumes. The flow before the meter goes into the tank, making it easier to calculate the amount loaded onto the ship; this should be clearly specified in the operating procedures. The operation becomes very convenient, and a bypass system needs to be designed during the planning stage.
It must be directed at the oil tank; there’s no doubt about that. Generally, it’s designed to be directed at the oil tank!
When sweeping the vessel, be aware that the terminal procedures specify restrictions on using gas for purging.
We also face this problem at our terminal. When changing the type of fluid – for example, starting with 97# gasoline and then switching to chemical light oil – our approach is to use pipelines for circulation (there are two such pipelines). This is very complicated; we have also considered using ball-pushing devices, but the pipelines from our tank area to the terminal are too long, and there are also pipe supports and bends along the way. Is it possible to install ball-pushing devices, or are there any other good solutions? Additionally, our dock mass flow meters are equipped with bypasses, but to prevent leaks within these bypasses that could allow oil to reach the ship without passing through the flow meter, blind flanges have been installed.
For long-distance transportation, mass flow meters are usually installed as close as possible to the transport vessel (typically on the dock float), so as to prevent excessive discharge of the material. Based on our experience, mass flow meters cannot be equipped with bypasses; all materials must be metered before entering the ship. When sweeping, sweep from the dock in the direction of the tank area.