膨脹節習慣上(shang)也(ye)叫(jiao)補償(chang)(chang)器(qi)，或(huo)(huo)伸縮(suo)節。由構成(cheng)其工作主體(ti)(ti)的波(bo)紋管(guan)(guan)(guan)(guan)(guan)(一(yi)種彈性元件(jian)(jian))和(he)(he)端管(guan)(guan)(guan)(guan)(guan)、支架、法蘭、導管(guan)(guan)(guan)(guan)(guan)等附件(jian)(jian)組成(cheng)。 膨脹節是為(wei)了補償(chang)(chang)因溫度(du)差與機械振動引(yin)起(qi)的附加應(ying)力(li)，而(er)設置(zhi)在容(rong)器(qi)殼體(ti)(ti)或(huo)(huo)管(guan)(guan)(guan)(guan)(guan)道(dao)上(shang)的一(yi)種撓性結(jie)構。利用(yong)其工作主體(ti)(ti)波(bo)紋管(guan)(guan)(guan)(guan)(guan)的有效伸縮(suo)變形(xing)(xing)，以(yi)吸收管(guan)(guan)(guan)(guan)(guan)線、導管(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)等由熱(re)(re)脹冷縮(suo)等原因而(er)產生的尺寸變化(hua)，或(huo)(huo)補償(chang)(chang)管(guan)(guan)(guan)(guan)(guan)線、導管(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)等的軸向(xiang)、橫向(xiang)和(he)(he)角(jiao)向(xiang)位(wei)移。也(ye)可用(yong)于降噪減振。供熱(re)(re)上(shang)，為(wei)了防止(zhi)供熱(re)(re)管(guan)(guan)(guan)(guan)(guan)道(dao)升溫時(shi)，由于熱(re)(re)伸長或(huo)(huo)溫度(du)應(ying)力(li)而(er)引(yin)起(qi)管(guan)(guan)(guan)(guan)(guan)道(dao)變形(xing)(xing)或(huo)(huo)破壞，需要在管(guan)(guan)(guan)(guan)(guan)道(dao)上(shang)設置(zhi)補償(chang)(chang)器(qi)，以(yi)補償(chang)(chang)管(guan)(guan)(guan)(guan)(guan)道(dao)的熱(re)(re)伸長，從而(er)減小管(guan)(guan)(guan)(guan)(guan)壁的應(ying)力(li)和(he)(he)作用(yong)在閥件(jian)(jian)或(huo)(huo)支架結(jie)構上(shang)的作用(yong)力(li)。