<跨度风格=“字体大小：12磅;”> <强>膨胀接头和环路 可以在其中包含与流体的任何管道系统需要温度高于正常室温升高。大多数管道中的商业系统是由金属的;公共管道材料包括铜，黑色铁，钢和不锈钢。当热量被施加到金属时，其经历的热膨胀。膨胀速率取决于金属和施加的热量。In piping, there are two directions in which thermally expansion can take place: circumferential and longitudinal. Circumferential lengthening is negligible and therefore is not a concern. But longitudinal expansion, depending on how long a pipe is run, can be several inches or more. Because piping is rigid, if the change in length is not provided for via expansion fittings or loops, the pipes can shear the connections and cause ruptures. Different metals expand at different rates, but all expand with the addition of heat. Expansion fittings and loops allow the piping to expand without failure.