膨脹節習慣上(shang)(shang)也叫補償(chang)(chang)器，或(huo)伸(shen)(shen)縮節。由(you)構成其(qi)工(gong)作(zuo)(zuo)主體(ti)(ti)的(de)波(bo)紋(wen)管(guan)(guan)(guan)(一種彈性(xing)元件(jian)(jian))和(he)(he)端管(guan)(guan)(guan)、支架、法(fa)蘭、導管(guan)(guan)(guan)等附(fu)件(jian)(jian)組(zu)成。 膨脹節是為(wei)了補償(chang)(chang)因(yin)溫(wen)度差與機械振動引(yin)起的(de)附(fu)加應力，而設置在(zai)(zai)容(rong)器殼體(ti)(ti)或(huo)管(guan)(guan)(guan)道(dao)(dao)上(shang)(shang)的(de)一種撓(nao)性(xing)結構。利用(yong)其(qi)工(gong)作(zuo)(zuo)主體(ti)(ti)波(bo)紋(wen)管(guan)(guan)(guan)的(de)有效伸(shen)(shen)縮變(bian)(bian)形(xing)，以吸收管(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)、容(rong)器等由(you)熱(re)(re)脹冷縮等原(yuan)因(yin)而產生的(de)尺寸(cun)變(bian)(bian)化(hua)，或(huo)補償(chang)(chang)管(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)、容(rong)器等的(de)軸向、橫向和(he)(he)角(jiao)向位移。也可(ke)用(yong)于(yu)降噪(zao)減振。供(gong)熱(re)(re)上(shang)(shang)，為(wei)了防止供(gong)熱(re)(re)管(guan)(guan)(guan)道(dao)(dao)升溫(wen)時，由(you)于(yu)熱(re)(re)伸(shen)(shen)長(chang)或(huo)溫(wen)度應力而引(yin)起管(guan)(guan)(guan)道(dao)(dao)變(bian)(bian)形(xing)或(huo)破壞，需要在(zai)(zai)管(guan)(guan)(guan)道(dao)(dao)上(shang)(shang)設置補償(chang)(chang)器，以補償(chang)(chang)管(guan)(guan)(guan)道(dao)(dao)的(de)熱(re)(re)伸(shen)(shen)長(chang)，從(cong)而減小管(guan)(guan)(guan)壁(bi)的(de)應力和(he)(he)作(zuo)(zuo)用(yong)在(zai)(zai)閥(fa)件(jian)(jian)或(huo)支架結構上(shang)(shang)的(de)作(zuo)(zuo)用(yong)力。