What key feature does a by-pass valve provide in high-pressure systems?

The correct choice emphasizes that a by-pass valve is used in high-pressure systems primarily to maintain and manage the flow of fluid while also performing critical functions such as pressure regulation and temperature control. In particular, the mention of ensuring that the main valve warms the downstream pipe relates to temperature management, facilitating smooth operations and reducing thermal shock when fluid flows through the system.

The by-pass valve operates by allowing a controlled amount of flow to bypass the main valve, which can help maintain a certain temperature or pressure balance in the system. This feature is crucial in preventing the downstream pipes and components from experiencing extreme conditions that could lead to damage or inefficiency.

This understanding clarifies the function of a by-pass valve and highlights its importance in maintaining the integrity and performance of high-pressure systems.