What is the initial step in the procedure for shutting down a line?

The initial step in the procedure for shutting down a line involves throttling down. This action is critical as it allows for a gradual reduction of flow through the line, which helps to minimize shock to the system and prevents potential damage. Throttling down controls the rate at which the system pressure decreases, reducing the likelihood of creating a vacuum or causing other pressure-related issues.

Properly managing this initial step contributes to the safety and integrity of the entire system. It establishes a controlled environment as other shutdown procedures follow, such as closing gate valves or shutting down pumps. In contrast, simply shutting down a pump or gating down without first controlling the flow could lead to sudden changes in pressure and flow, which may be hazardous.