Did you know that liquids pipelines can transport different types and grades of liquid petroleum products in the same pipeline? Called “batching”, this process makes efficient use of existing pipeline capacity, which lowers the price consumers pay for oil and its by-products.
Crude oil comes in a number of grades and varieties, with vast differences in colour, weight and viscosity. These are some of the important specifications used to separate the products when they’re shipped in batches along energy transmission pipeline systems.
Batching involves using the same pipeline to ship different types and/or grades of liquid products, such as light crude, heavy crude, or diluted bitumen.
Pipeline companies have set specifications for each product that’s batched for shipping. Specifications include viscosity (the degree to which the crude oil resists flow), density (heavy crude versus light crude), temperature, volatility, sulphur content (sweet crude is low in sulphur and sour crude is high in sulphur), and sediment-and-water content. Trans Mountain is the only pipeline in North America that batches both refined products and crude oil for shipping. Examples of refined products are diesel, gasoline and jet fuels.
Here’s a simple outline of how it works. The pipeline operator sends a batch of light crude along the line for a few hours. Once that light crude batch moves through the pipe, the operator can then switch to a batch of heavy crude, and a few hours later another shift can occur… to diluted bitumen. The best way to think of it is as a “batch train” or a series of rail cars, with one product following another through the pipeline over a specific stretch of time.
The pipeline operator uses scheduling to track batches of customers’ products. Here are three important steps involved in transporting batched products:
One of the key factors in batching is limiting the amount of product that’s mixed in with other products. Any mixed products must be placed in a separate tank and reprocessed to separate. Some pipeline systems use a batch mechanism, called a ‘pipeline pig’, to separate individual parcels, but the usual approach is to mix together ‘like crudes’ in a common stream. (RBN Energy Inc., S. Fielden. 2013.).
CEPA members monitor and strictly enforce all standards and specifications for the batched products transported on their pipelines. Although some of the product coming out of the pipeline may be mixed with other customers’ products, the batch still has to meet the same product specifications, e.g., heavy crude, light crude, or diluted bitumen. Some pipelines specialize in the batching and transporting of liquid petroleum gas products, such as propane and butane.