壓(ya)力(li)容(rong)(rong)器法蘭(lan)(lan)是(shi)(shi)壓(ya)力(li)容(rong)(rong)器的(de)(de)(de)常用(yong)部(bu)(bu)件(jian)(jian)，是(shi)(shi)連接(jie)(jie)各種(zhong)壓(ya)力(li)容(rong)(rong)器部(bu)(bu)件(jian)(jian)的(de)(de)(de)基本元(yuan)件(jian)(jian)，廣泛地用(yong)于石(shi)油、石(shi)化(hua)、電力(li)、原子(zi)能、輕工等領域。對(dui)于容(rong)(rong)器而(er)言，應該是(shi)(shi)一個組(zu)件(jian)(jian)，包括(kuo)法蘭(lan)(lan)、墊(dian)片和連接(jie)(jie)螺(luo)(luo)(luo)栓或(huo)螺(luo)(luo)(luo)柱以(yi)及螺(luo)(luo)(luo)母，其(qi)作(zuo)用(yong)是(shi)(shi)使(shi)不(bu)同(tong)(tong)的(de)(de)(de)受壓(ya)元(yuan)件(jian)(jian)組(zu)合在一起(qi)，同(tong)(tong)時(shi)保證連接(jie)(jie)部(bu)(bu)位不(bu)發(fa)生泄(xie)(xie)漏(lou)。法蘭(lan)(lan)連接(jie)(jie)的(de)(de)(de)主要失(shi)效(xiao)形(xing)式為(wei)接(jie)(jie)頭的(de)(de)(de)剛度(du)失(shi)效(xiao)，其(qi)外部(bu)(bu)表現型式為(wei)泄(xie)(xie)漏(lou)。壓(ya)力(li)容(rong)(rong)器內部(bu)(bu)的(de)(de)(de)介質具(ju)有(you)高溫、高壓(ya)的(de)(de)(de)特(te)點，同(tong)(tong)時(shi)具(ju)有(you)易燃、易爆的(de)(de)(de)特(te)性或(huo)毒性，一旦產(chan)生泄(xie)(xie)漏(lou)，將發(fa)生嚴(yan)重(zhong)的(de)(de)(de)次生災害，嚴(yan)重(zhong)威脅壓(ya)力(li)容(rong)(rong)器本體和周圍設(she)備以(yi)及人員的(de)(de)(de)安全。因此容(rong)(rong)器法蘭(lan)(lan)的(de)(de)(de)設(she)計和選用(yong)應優先考慮的(de)(de)(de)因素是(shi)(shi)整體密封(feng)性能。

  我國(guo)壓力(li)容(rong)器(qi)法(fa)蘭(lan)(lan)標(biao)準自成體系。最(zui)早的(de)壓力(li)容(rong)器(qi)法(fa)蘭(lan)(lan)標(biao)準可以追溯(su)到(dao)20世(shi)紀70年代，當時使用的(de)是由原一機部(bu)、石油部(bu)、化工(gong)部(bu)三部(bu)共(gong)同發布(bu)的(de)壓力(li)容(rong)器(qi)法(fa)蘭(lan)(lan)行業標(biao)準JB 1157~1164-1973.經過長期的(de)試用及(ji)不斷的(de)修訂，目前最(zui)新的(de)標(biao)準為NB/T 47020~47027-2012《壓力(li)容(rong)器(qi)法(fa)蘭(lan)(lan)》。

  就法蘭的結(jie)構型式和(he)工作原理(li)而言(yan)，壓力容(rong)器(qi)法蘭和(he)管(guan)法蘭沒有多大差異。比較明顯的區別(bie)是(shi)，壓力容(rong)器(qi)法蘭規格較大，與各類壓力容(rong)器(qi)連接(jie)(jie)使用；而管(guan)法蘭常(chang)常(chang)與管(guan)子直接(jie)(jie)連接(jie)(jie)或與泵(beng)、閥、機等(deng)管(guan)道(dao)設(she)備的進出口管(guan)子連接(jie)(jie)使用。

  壓(ya)(ya)(ya)(ya)力(li)(li)(li)容器法蘭工(gong)作(zuo)(zuo)原理為：當對法蘭螺栓(shuan)(shuan)施加預緊力(li)(li)(li)時(shi)，螺栓(shuan)(shuan)力(li)(li)(li)通過(guo)法蘭環(huan)把墊片(pian)(pian)壓(ya)(ya)(ya)(ya)緊，迫使(shi)(shi)法蘭墊片(pian)(pian)產生壓(ya)(ya)(ya)(ya)縮(suo)變(bian)形(xing)。當螺栓(shuan)(shuan)力(li)(li)(li)達到(dao)一定數值后(hou)，迫使(shi)(shi)法蘭密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面和墊片(pian)(pian)上(shang)的(de)(de)(de)(de)凹(ao)凸不平(ping)面借助墊片(pian)(pian)變(bian)形(xing)而(er)填滿，這(zhe)就為阻止流體介(jie)質泄漏創(chuang)造了初始(shi)(shi)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)條件。此時(shi)墊片(pian)(pian)單位有效(xiao)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面積上(shang)的(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)緊力(li)(li)(li)稱為墊片(pian)(pian)的(de)(de)(de)(de)初始(shi)(shi)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)。當設備(bei)或管道(dao)承受介(jie)質壓(ya)(ya)(ya)(ya)力(li)(li)(li)后(hou)，螺栓(shuan)(shuan)受到(dao)拉伸應(ying)力(li)(li)(li)而(er)伸長，法蘭密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面沿著彼此分離的(de)(de)(de)(de)方向移動，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面與墊片(pian)(pian)之間(jian)的(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)緊力(li)(li)(li)下降，墊片(pian)(pian)的(de)(de)(de)(de)壓(ya)(ya)(ya)(ya)縮(suo)量減少，預緊密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)下降。如(ru)果這(zhe)時(shi)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)墊片(pian)(pian)具有足夠的(de)(de)(de)(de)回(hui)彈能力(li)(li)(li)，墊片(pian)(pian)的(de)(de)(de)(de)變(bian)形(xing)能補償螺栓(shuan)(shuan)和密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)面的(de)(de)(de)(de)分離值，而(er)使(shi)(shi)預緊密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)只下降到(dao)不小于(yu)工(gong)作(zuo)(zuo)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)，則(ze)法蘭依(yi)然保持(chi)良好的(de)(de)(de)(de)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)狀態。反之，如(ru)墊片(pian)(pian)的(de)(de)(de)(de)回(hui)彈能力(li)(li)(li)不足，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)下降到(dao)工(gong)作(zuo)(zuo)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)(ya)以下，甚至密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)口(kou)重新出現(xian)縫(feng)隙，則(ze)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)(feng)失效(xiao)。