Chapter 23

Steam Boilers

Safety Issues

All combustion equipment must be operated properly to prevent dangerous conditions or disasters from occurring, causing personal injury and property loss. The basic cause of boiler explosions is ignition of a combustible gas that has accumulated within the boiler. This situation can arise in a number of ways, for example fuel, air, or ignition is interrupted for some reason, the flame extinguishes, and combustible gas accumulates and is reignited. Another example is when a number of unsuccessful attempts at ignition occur without the appropriate purging of accumulated combustible gas. There is a tremendous amount of stored energy within a boiler. The state change of superheated water from a hot liquid to a vapor (steam) releases an enormous amount of energy. For example, 1 ft3 of water will expand to 1,600 ft3 when it turns to steam. Boilers must be inspected regularly based on manufacturer’s recommendations. Pressure vessel integrity, checking of safety relief valves, water cutoff devices and proper float operation, gauges and water level indicators should all be inspected. The boiler’s fuel and burner system require proper inspection and maintenance to ensure efficient operation, heat transfer and correct flame detection.

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