壓力(li)容(rong)(rong)器法蘭是(shi)(shi)壓力(li)容(rong)(rong)器的(de)常(chang)用(yong)部(bu)(bu)(bu)(bu)件(jian)，是(shi)(shi)連(lian)接各種壓力(li)容(rong)(rong)器部(bu)(bu)(bu)(bu)件(jian)的(de)基(ji)本元(yuan)件(jian)，廣泛地用(yong)于石(shi)(shi)油、石(shi)(shi)化、電力(li)、原子能、輕(qing)工等領域。對于容(rong)(rong)器而言，應該(gai)是(shi)(shi)一(yi)個組(zu)件(jian)，包括法蘭、墊(dian)片和連(lian)接螺(luo)(luo)栓或(huo)(huo)螺(luo)(luo)柱以(yi)(yi)及(ji)螺(luo)(luo)母，其作用(yong)是(shi)(shi)使不同的(de)受壓元(yuan)件(jian)組(zu)合在(zai)一(yi)起，同時保證連(lian)接部(bu)(bu)(bu)(bu)位不發生(sheng)泄(xie)漏(lou)。法蘭連(lian)接的(de)主要失(shi)效(xiao)形式為接頭的(de)剛度失(shi)效(xiao)，其外部(bu)(bu)(bu)(bu)表現型式為泄(xie)漏(lou)。壓力(li)容(rong)(rong)器內部(bu)(bu)(bu)(bu)的(de)介質(zhi)具有(you)高溫、高壓的(de)特點，同時具有(you)易燃、易爆的(de)特性(xing)或(huo)(huo)毒性(xing)，一(yi)旦產生(sheng)泄(xie)漏(lou)，將發生(sheng)嚴(yan)重的(de)次生(sheng)災害，嚴(yan)重威脅壓力(li)容(rong)(rong)器本體和周圍設(she)備以(yi)(yi)及(ji)人員的(de)安全。因(yin)此容(rong)(rong)器法蘭的(de)設(she)計和選用(yong)應優(you)先(xian)考(kao)慮的(de)因(yin)素是(shi)(shi)整體密封(feng)性(xing)能。

  我國壓力(li)容(rong)器(qi)法(fa)蘭標(biao)(biao)準(zhun)(zhun)自成體系。最早(zao)的壓力(li)容(rong)器(qi)法(fa)蘭標(biao)(biao)準(zhun)(zhun)可以(yi)追溯到20世紀70年代，當時使用(yong)的是由原一機(ji)部(bu)(bu)、石(shi)油部(bu)(bu)、化工部(bu)(bu)三部(bu)(bu)共同(tong)發布的壓力(li)容(rong)器(qi)法(fa)蘭行(xing)業標(biao)(biao)準(zhun)(zhun)JB 1157~1164-1973.經過長期(qi)的試用(yong)及(ji)不斷的修訂(ding)，目前(qian)最新的標(biao)(biao)準(zhun)(zhun)為NB/T 47020~47027-2012《壓力(li)容(rong)器(qi)法(fa)蘭》。

  就(jiu)法蘭(lan)的(de)結構(gou)型式和(he)工(gong)作(zuo)原理(li)而言(yan)，壓(ya)(ya)力容(rong)器(qi)法蘭(lan)和(he)管(guan)(guan)法蘭(lan)沒有多大差異。比較明(ming)顯的(de)區別是，壓(ya)(ya)力容(rong)器(qi)法蘭(lan)規格較大，與各類壓(ya)(ya)力容(rong)器(qi)連接(jie)使用(yong)；而管(guan)(guan)法蘭(lan)常常與管(guan)(guan)子(zi)直接(jie)連接(jie)或(huo)與泵(beng)、閥、機等管(guan)(guan)道設備(bei)的(de)進出(chu)口管(guan)(guan)子(zi)連接(jie)使用(yong)。

  壓(ya)(ya)(ya)(ya)力(li)(li)容器法蘭工(gong)作(zuo)(zuo)原理為：當(dang)對(dui)法蘭螺(luo)(luo)栓(shuan)(shuan)施加預緊(jin)力(li)(li)時，螺(luo)(luo)栓(shuan)(shuan)力(li)(li)通過(guo)法蘭環把墊片(pian)壓(ya)(ya)(ya)(ya)緊(jin)，迫使(shi)(shi)法蘭墊片(pian)產生壓(ya)(ya)(ya)(ya)縮(suo)變形。當(dang)螺(luo)(luo)栓(shuan)(shuan)力(li)(li)達到一定(ding)數值(zhi)后，迫使(shi)(shi)法蘭密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)和墊片(pian)上(shang)的(de)(de)(de)凹凸(tu)不平面(mian)(mian)借助(zhu)墊片(pian)變形而(er)填滿，這就為阻止流體介(jie)質(zhi)(zhi)泄漏創造了初(chu)始密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)條件。此(ci)時墊片(pian)單位(wei)有效密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)積上(shang)的(de)(de)(de)壓(ya)(ya)(ya)(ya)緊(jin)力(li)(li)稱為墊片(pian)的(de)(de)(de)初(chu)始密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)。當(dang)設(she)備或管道(dao)承(cheng)受介(jie)質(zhi)(zhi)壓(ya)(ya)(ya)(ya)力(li)(li)后，螺(luo)(luo)栓(shuan)(shuan)受到拉(la)伸應力(li)(li)而(er)伸長(chang)，法蘭密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)沿(yan)著彼(bi)此(ci)分離(li)的(de)(de)(de)方向移動，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)與墊片(pian)之間的(de)(de)(de)壓(ya)(ya)(ya)(ya)緊(jin)力(li)(li)下降，墊片(pian)的(de)(de)(de)壓(ya)(ya)(ya)(ya)縮(suo)量減少，預緊(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)下降。如(ru)果(guo)這時密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)墊片(pian)具有足(zu)夠(gou)的(de)(de)(de)回彈能(neng)力(li)(li)，墊片(pian)的(de)(de)(de)變形能(neng)補償螺(luo)(luo)栓(shuan)(shuan)和密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)的(de)(de)(de)分離(li)值(zhi)，而(er)使(shi)(shi)預緊(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)只(zhi)下降到不小于工(gong)作(zuo)(zuo)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)，則法蘭依然(ran)保持良好(hao)的(de)(de)(de)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)狀態。反(fan)之，如(ru)墊片(pian)的(de)(de)(de)回彈能(neng)力(li)(li)不足(zu)，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)下降到工(gong)作(zuo)(zuo)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)(ya)以下，甚至密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)口重(zhong)新出(chu)現縫隙，則密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)失效。