What type of refractory is preferred for small repairs in a boiler?

Castable fireclay is preferred for small repairs in a boiler due to its specific characteristics that make it suitable for high-temperature applications. It is a type of refractory material that can be easily mixed and poured into molds or used to patch damaged areas, allowing for a seamless application over existing surfaces. This material provides good resistance to thermal cycling and chemical attack, which are common in boiler environments.

In addition, castable fireclay can be set up at a relatively low temperature compared to other refractory types, making it ideal for on-site repairs. Its ability to self-support and bond well with existing structures ensures durability and longevity of the repair work, which is crucial in maintaining the efficiency and safety of boiler operations. This makes castable fireclay the preferred choice for those instances requiring quick and effective refractory repairs.