Design of long-distance pipeline corridors and purging issues

Should it be air purging or steam purging? For steam purging, it is necessary to ensure that the pipelines are designed to withstand the purging temperature; otherwise, the pipelines may expand and shift when heated, leading to accidents. It is best to carry out purging from the factory area towards the dock, so that the gas supply can be utilized. Where there are sections that need to be crossed, it is advisable to install liquid separation tanks at the front end – these help to remove liquids from the pipes, and any debris can also settle there, making it easier to clean them. If possible, purging should be carried out in segments

This post was last edited by Liu Fengrui on 2015-11-25 20:25. Thank you for your reply! I think: 1. Due to the excessive length of the pipeline, as well as the elevation changes along its route, the flow in the pipeline is insufficient, making it difficult to achieve optimal results during purging. Is it possible to use the oil to be shipped next time to push the mixture in the direction of loading, i.e., using high-quality oil to replace lower-quality oil, so as to give the shipping party an advantage? Line depressurization is at the inlet of the on-site storage tank. 2. For oils with similar properties, sequential transportation should be employed, and the transfer must be continuous (taking into account the loading time as well as minimizing or avoiding mixing of oils). This saves space in the conduit shaft occupied by pipes, as well as reducing investment and maintenance costs. Is the above feasible? Are there any other methods?

1. Due to the excessive length of the pipeline, as well as the elevation changes along its route, the pipeline cannot flow at full capacity, making it difficult to achieve optimal results during purging. Is it possible to use the oil to be shipped next time to push the mixture in the direction of loading, i.e., using high-quality oil to replace lower-quality oil, so as to give the shipping party an advantage? Line depressurization is at the inlet of the on-site storage tank. The design takes into account measures for air defense at higher points and drainage at lower points, so that cleaning through purging is more effective. Purging should be carried out as much as possible; however, dealing with the oil that comes out at the top poses a problem, and there are other potential issues as well. 2. For oils with similar properties, sequential transportation in a continuous manner should be employed (taking into account the time required for loading onto ships, as well as minimizing or avoiding mixing of oils). This saves space in the conduit shaft occupied by pipes, as well as reducing investment and maintenance costs. Is the above feasible? Are there any other methods? I’m not familiar with this, but CNPC’s oil pipelines can transport both diesel and gasoline

The biggest characteristic of loading and unloading ships is that, unlike long-distance transportation which allows for continuous transfer, these processes are intermittent; in practice, it is not possible to handle one ship after another without interruption. 1. For cases with a large number of varieties, it is generally recommended to use dedicated pipelines for each variety, as factors such as the type of variety need to be taken into account. However, the investment required for 10 km of pipelines is not negligible; if the annual volume of goods is small, it is suggested that the client consider using road transport instead of ship transport ； 2. First, determine whether insulation or heat insulation is required based on the properties of the material. For 10km pipelines, if cleaning is considered every time, it is necessary to clean them onto the ship after each loading process (which is a prerequisite for shipping). This requires a large amount of nitrogen each time, resulting in cost expenses and delays at the dock. Moreover, the measurement accuracy is poor and the cleaning is not thorough. Under normal circumstances, pigging is not considered for terminal pipelines unless there are special situations. Inspection and cleaning of the pipeline can only be carried out from the dock to the storage tank.

1. For a pipeline corridor of 10 km in length, it is inevitable that it will pass through public areas. After pressure testing at the highest and lowest points of the pipelines, these areas must be sealed with welds; leaving a valve in place represents a serious safety hazard； 2. Sequential transportation is a concept suited for long-distance transport; it cannot be implemented at docks. Even when scheduled properly, it takes several hours for one ship to depart and another to arrive, including berthing and unberthing times.

Okay! This makes the thinking clearer. During the design phase, it was taken into account that for these 12 types of oils with low production volumes, transportation by road (within 500 kilometers) or rail is used; the remaining types are optimized further, and they are grouped together based on similar properties and annual production volumes (taking into account dock handling time and shipping schedules). Those for which strict quality requirements do not apply can share the same pipeline. This saves a lot of space in the utility tunnel, reducing investment costs. The pipeline only needs to be handled during maintenance and welding work; purging the pipeline is definitely not an option. Normally, after installing the pipeline on the ship, only high-quality materials can be used to replace lower-quality ones.

If the requirements are strict, should one hire a professional purging and cleaning company?

Additionally, for the 10km pipeline, it is necessary to carefully verify the head capacity of the loading pump. Building 10 km is not easy either; try to leave as much headroom in the pipe tunnels as possible to facilitate the addition of pipes in the future.

Currently, for pipeline purging, the purging medium is selected based on the different media used; it is recommended to design the system in such a way that balls can pass through it. You can message me privately. 769370124