Steel boilers are generally classified as which type?

Steel boilers are primarily classified as water tube boilers due to their design and operation. In a water tube boiler, water circulates within tubes that are heated externally by combustion gases. This design allows for higher pressures and temperatures compared to fire tube boilers, where hot gases pass through tubes surrounded by water.

Water tube boilers are advantageous in various applications for several reasons, including their ability to quickly respond to fluctuations in steam demand and their high efficiency in heat transfer. The construction and layout allow for better control over the heating process, making these boilers suitable for industrial and commercial settings where high-performance and reliability are critical.

Other types mentioned, such as vapour tube, square sectional, and oval sectional boilers, do not represent widely recognized classifications in the standard boiler industry. Thus, the classification of steel boilers as water tube boilers is accurate and reflects their common use and functional attributes in the field of steam generation and heating systems.