Which type of valve body can be used on water service up to temperatures of about 250°C?

The correct type of valve body for water service up to temperatures of about 250°C is cast iron. Cast iron is known for its good thermal conductivity, resistance to deformation under high temperatures, and durability, making it suitable for various industrial applications, including water services at elevated temperatures.

While stainless steel can withstand higher temperatures than cast iron and has excellent corrosion resistance, it is also more costly and may not be necessary for all water service applications. This makes cast iron a more practical and economical choice for situations where temperatures do not exceed 250°C.

Plastic valves generally have much lower temperature tolerance and are not suitable for high-temperature applications because they can warp or melt, directly ruling them out for this specific temperature requirement. Copper, while a good conductor of heat and often used for plumbing systems, also has limited temperature resistance compared to cast iron and can degrade over time when exposed to high temperatures and certain chemicals. Thus, the application of cast iron in this scenario is the most appropriate, offering a good balance between temperature resistance, strength, and cost-effectiveness.