膨脹節習慣上也(ye)叫補(bu)償器(qi)(qi)，或(huo)伸縮(suo)(suo)節。由構成其工作主體(ti)(ti)(ti)的(de)(de)波紋管(guan)(guan)(guan)(guan)(guan)(guan)(一(yi)種(zhong)彈(dan)性元(yuan)件(jian))和端管(guan)(guan)(guan)(guan)(guan)(guan)、支架(jia)、法蘭、導(dao)管(guan)(guan)(guan)(guan)(guan)(guan)等(deng)(deng)附件(jian)組成。 膨脹節是為了(le)補(bu)償因溫(wen)度差與機械振(zhen)動(dong)引起(qi)的(de)(de)附加(jia)應力，而(er)(er)設置在(zai)容(rong)器(qi)(qi)殼體(ti)(ti)(ti)或(huo)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)上的(de)(de)一(yi)種(zhong)撓性結(jie)構。利用(yong)其工作主體(ti)(ti)(ti)波紋管(guan)(guan)(guan)(guan)(guan)(guan)的(de)(de)有效伸縮(suo)(suo)變形(xing)，以吸收管(guan)(guan)(guan)(guan)(guan)(guan)線、導(dao)管(guan)(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)(qi)等(deng)(deng)由熱(re)(re)脹冷縮(suo)(suo)等(deng)(deng)原因而(er)(er)產生的(de)(de)尺(chi)寸(cun)變化，或(huo)補(bu)償管(guan)(guan)(guan)(guan)(guan)(guan)線、導(dao)管(guan)(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)(qi)等(deng)(deng)的(de)(de)軸(zhou)向(xiang)、橫(heng)向(xiang)和角(jiao)向(xiang)位移。也(ye)可(ke)用(yong)于(yu)降噪減(jian)振(zhen)。供熱(re)(re)上，為了(le)防止供熱(re)(re)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)升溫(wen)時，由于(yu)熱(re)(re)伸長或(huo)溫(wen)度應力而(er)(er)引起(qi)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)變形(xing)或(huo)破(po)壞，需(xu)要在(zai)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)上設置補(bu)償器(qi)(qi)，以補(bu)償管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)的(de)(de)熱(re)(re)伸長，從而(er)(er)減(jian)小(xiao)管(guan)(guan)(guan)(guan)(guan)(guan)壁的(de)(de)應力和作用(yong)在(zai)閥件(jian)或(huo)支架(jia)結(jie)構上的(de)(de)作用(yong)力。