膨脹(zhang)節(jie)習慣(guan)上(shang)(shang)也叫補(bu)(bu)償器(qi)，或伸縮(suo)節(jie)。由構成其(qi)工作(zuo)主體(ti)的波(bo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(一種(zhong)彈性元件)和端管(guan)(guan)(guan)(guan)(guan)(guan)、支(zhi)架、法蘭、導管(guan)(guan)(guan)(guan)(guan)(guan)等附件組成。 膨脹(zhang)節(jie)是(shi)為了(le)補(bu)(bu)償因溫度差與機械振(zhen)動引起(qi)的附加(jia)應力，而設(she)置在容(rong)器(qi)殼體(ti)或管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)上(shang)(shang)的一種(zhong)撓性結構。利用(yong)(yong)其(qi)工作(zuo)主體(ti)波(bo)紋管(guan)(guan)(guan)(guan)(guan)(guan)的有效伸縮(suo)變(bian)(bian)形(xing)，以吸(xi)收管(guan)(guan)(guan)(guan)(guan)(guan)線、導管(guan)(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)等由熱(re)脹(zhang)冷縮(suo)等原因而產生的尺寸變(bian)(bian)化，或補(bu)(bu)償管(guan)(guan)(guan)(guan)(guan)(guan)線、導管(guan)(guan)(guan)(guan)(guan)(guan)、容(rong)器(qi)等的軸(zhou)向(xiang)、橫向(xiang)和角向(xiang)位移(yi)。也可(ke)用(yong)(yong)于(yu)降噪(zao)減(jian)振(zhen)。供熱(re)上(shang)(shang)，為了(le)防止供熱(re)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)升溫時，由于(yu)熱(re)伸長或溫度應力而引起(qi)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)變(bian)(bian)形(xing)或破(po)壞，需要在管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)上(shang)(shang)設(she)置補(bu)(bu)償器(qi)，以補(bu)(bu)償管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)(dao)的熱(re)伸長，從而減(jian)小管(guan)(guan)(guan)(guan)(guan)(guan)壁的應力和作(zuo)用(yong)(yong)在閥(fa)件或支(zhi)架結構上(shang)(shang)的作(zuo)用(yong)(yong)力。