Which of the following is NOT a type of pipeline system valve?

The correct response is that a hydraulic valve is not traditionally categorized as a type of pipeline system valve in the same manner as the others listed. A check valve, thermal relief valve, and ball valve are all specifically designed for managing flow and pressure within pipeline systems.

A check valve allows fluid to flow in one direction while preventing backflow, which is essential for maintaining system integrity. A thermal relief valve operates to relieve pressure buildup due to thermal expansion, thereby protecting the system from potential damage. A ball valve is widely used for on/off control of flow, effectively sealing or allowing fluid movement as needed.

In contrast, while "hydraulic valve" can refer to various types of valves within the hydraulic systems used to control fluid power and operate machinery, it does not represent a specific category of pipeline valves aimed specifically at flow or pressure management in the same distinct way as check, thermal relief, or ball valves do.