"Line Displacement" at an oil terminal facility is conducted when there is a change of what?

The concept of "Line Displacement" during operations at an oil terminal is crucial for ensuring the integrity of product transfers and minimizing contamination. When there is a change of product during the final phase of loading, line displacement is necessary to ensure that the cargo lines and equipment are cleared of the previous product before the new product is introduced. This process helps prevent any mixing of incompatible products which could lead to degradation of quality or even hazardous situations.

The reason this option is especially valid is that as the loading operations progress, prompting a switch to a different product could create a risk of cross-contamination. Hence, utilizing line displacement allows for the effective removal of residual quantities of the previous product.

The other options refer to different stages of the loading process or types of changes that do not inherently demand the line displacement procedure. For instance, changing the product before loading may not require displacement if proper procedures are in place to ensure cleanliness, and cargo lines at the terminal before loading focus on preparation rather than displacement. Similarly, considering a product change after discharge involves different operational protocols concerning cleanup and maintenance rather than immediate product transfers. Thus, the emphasis on line displacement occurring during a change of product in the final phase of loading makes this option the most appropriate in the context of