The damage of steam pipes in ship engine rooms is a common fault. The use of thermal imagers is of important value to steam pipe breakage monitoring. The judgment, the monitoring process, the influence of inner environment on monitoring and the corresponding measures when using infrared imagers to monitor steam pipes in daily work are presented. In our daily work, the qualitative judgment is mainly implemented by using a direct-comparison method. During monitoring, the distance between the thermal imager and the target to be measured, the angle of the thermal imager and the ambient temperature in engine compartments have less influences on measurement result judgment. Instead, the emissivity of other heat sources and objects has a great influence on measurement result judgment.