What are the hazards of overheating during boiler operation for pipeline use?

Various soda water pipes and boiler heating surface tubes have their service life designed based on certain operating temperatures and stresses. If the operating temperature exceeds the design temperature, even if overheating does not occur, it will reduce the stability of the metal structure, increase the creep rate, and ultimately shorten its service life. According to experimental studies, the time it takes for the material to reach failure is inversely proportional to the creep rate, and it decreases exponentially as the temperature rises. Based on this principle, under the same stress conditions, the service life at different temperatures can be estimated using the Larson-Miller approximation equation.

This post was last edited by ray1513 on 2011-7-8 at 13:26. When the steam temperature exceeds the rated value during operation, it is referred to as overtemperature. When the wall temperature of a heating surface tube or steam pipeline exceeds the maximum allowable temperature for that type of steel, it is referred to as overheating. 　　All types of steel have specified temperature ranges for use, or in other words, an allowable maximum operating temperature. It can operate safely for its service life within the permitted operating temperature range. 　　Over-temperature during operation. It may cause overheating of the tube wall sometimes, but not necessarily. If the rated operating temperature is much lower than the allowable maximum temperature of the steel, overheating will not necessarily occur even if the temperature rises above that limit. For example, the maximum allowable operating temperature for 12Cr1MoV steel is 580°C, while the rated steam temperature is 540°C; if the temperature reaches 550°C during operation, this is generally considered to be an over-temperature condition, but it does not represent overheating for the main steam pipes. 　　When the actual wall temperature exceeds the maximum operating temperature of the steel, the mechanical properties and microstructure of the metal change, the creep rate increases, and ultimately the pipeline ruptures. To this end, during operation, it is necessary to keep records of over-temperature conditions in the main steam pipes, superheater and reheater pipes, as well as the corresponding steam guide pipes. By tracking the duration and extent of such over-temperatures, it is possible to analyze the lifespan of these pipes, enhance supervision over them, and prevent overheating and sudden damage.