補(bu)(bu)償器(qi)習慣上也叫膨脹節(jie)(jie)，或伸縮節(jie)(jie)。由構成(cheng)其(qi)工(gong)作(zuo)主體的(de)(de)波紋管(guan)(guan)(guan)(guan)(guan)（一(yi)種彈(dan)性元(yuan)件）和(he)端(duan)管(guan)(guan)(guan)(guan)(guan)、支架(jia)、法蘭、導管(guan)(guan)(guan)(guan)(guan)等(deng)附件組成(cheng)。 屬于(yu)一(yi)種補(bu)(bu)償元(yuan)件。利用(yong)(yong)其(qi)工(gong)作(zuo)主體波紋管(guan)(guan)(guan)(guan)(guan)的(de)(de)有效伸縮變(bian)形，以吸(xi)收管(guan)(guan)(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)(guan)(guan)、容器(qi)等(deng)由熱脹冷(leng)縮等(deng)原(yuan)因而(er)產生(sheng)的(de)(de)尺(chi)寸變(bian)化，或補(bu)(bu)償管(guan)(guan)(guan)(guan)(guan)線(xian)、導管(guan)(guan)(guan)(guan)(guan)、容器(qi)等(deng)的(de)(de)軸(zhou)向(xiang)、橫向(xiang)和(he)角向(xiang)位移。也可(ke)用(yong)(yong)于(yu)降噪減振。在現代工(gong)業中用(yong)(yong)途廣泛。供熱上，為(wei)了防止供熱管(guan)(guan)(guan)(guan)(guan)道(dao)升(sheng)溫時，由于(yu)熱伸長或溫度應力(li)而(er)引(yin)起管(guan)(guan)(guan)(guan)(guan)道(dao)變(bian)形或破壞(huai)，需要(yao)在管(guan)(guan)(guan)(guan)(guan)道(dao)上設置補(bu)(bu)償器(qi)，以補(bu)(bu)償管(guan)(guan)(guan)(guan)(guan)道(dao)的(de)(de)熱伸長，從而(er)減小管(guan)(guan)(guan)(guan)(guan)壁的(de)(de)應力(li)和(he)作(zuo)用(yong)(yong)在閥件或支架(jia)結構上的(de)(de)作(zuo)用(yong)(yong)力(li)。