What type of valve must be provided in the feed-pipe near the boiler?

The type of valve that must be provided in the feed-pipe near the boiler is a check valve. This valve is critical for ensuring that water only flows in one direction into the boiler from the feed source. Its primary function is to prevent backflow, which can occur if there's a loss of pressure in the system or if the boiler begins to drain. Backflow can potentially lead to serious issues such as boiler contamination or damage, so using a check valve is essential for maintaining operational safety and integrity.

Other types of valves, such as globe, ball, or butterfly valves, serve different purposes in a piping system. While they can control the flow of liquids, they do not provide the required backflow prevention that a check valve does. Therefore, choosing a check valve for the feed-pipe fulfills a specific safety requirement that supports the overall performance and safety of the boiler system.