膨脹(zhang)節習慣上也叫補償(chang)(chang)器(qi)，或伸縮(suo)(suo)節。由構成其(qi)工作主(zhu)體的波(bo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(一種(zhong)彈性(xing)元件)和端管(guan)(guan)(guan)(guan)(guan)(guan)、支架(jia)、法(fa)蘭、導管(guan)(guan)(guan)(guan)(guan)(guan)等(deng)(deng)(deng)附(fu)件組成。 膨脹(zhang)節是為了補償(chang)(chang)因溫度(du)差(cha)與機械振動引起的附(fu)加(jia)應力(li)，而設置在容器(qi)殼體或管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)上的一種(zhong)撓性(xing)結構。利用(yong)(yong)其(qi)工作主(zhu)體波(bo)紋管(guan)(guan)(guan)(guan)(guan)(guan)的有效伸縮(suo)(suo)變(bian)形，以(yi)吸(xi)收(shou)管(guan)(guan)(guan)(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)(guan)(guan)(guan)、容器(qi)等(deng)(deng)(deng)由熱脹(zhang)冷縮(suo)(suo)等(deng)(deng)(deng)原因而產(chan)生的尺寸變(bian)化，或補償(chang)(chang)管(guan)(guan)(guan)(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)(guan)(guan)(guan)、容器(qi)等(deng)(deng)(deng)的軸向、橫向和角向位移。也可用(yong)(yong)于(yu)降噪(zao)減振。供(gong)熱上，為了防止供(gong)熱管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)升溫時，由于(yu)熱伸長或溫度(du)應力(li)而引起管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)變(bian)形或破壞，需要在管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)上設置補償(chang)(chang)器(qi)，以(yi)補償(chang)(chang)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)的熱伸長，從而減小管(guan)(guan)(guan)(guan)(guan)(guan)壁的應力(li)和作用(yong)(yong)在閥(fa)件或支架(jia)結構上的作用(yong)(yong)力(li)。