壓(ya)力(li)(li)(li)容(rong)器(qi)法蘭是(shi)壓(ya)力(li)(li)(li)容(rong)器(qi)的(de)(de)(de)常(chang)用部(bu)件，是(shi)連(lian)接各種壓(ya)力(li)(li)(li)容(rong)器(qi)部(bu)件的(de)(de)(de)基(ji)本(ben)元件，廣泛地用于(yu)(yu)石油、石化、電力(li)(li)(li)、原子(zi)能(neng)、輕工(gong)等領域(yu)。對(dui)于(yu)(yu)容(rong)器(qi)而言，應(ying)該是(shi)一個(ge)組件，包(bao)括法蘭、墊片(pian)和(he)連(lian)接螺栓(shuan)或(huo)螺柱以及(ji)(ji)螺母，其作用是(shi)使不同(tong)的(de)(de)(de)受壓(ya)元件組合在一起，同(tong)時保證連(lian)接部(bu)位不發(fa)生泄漏(lou)。法蘭連(lian)接的(de)(de)(de)主(zhu)要失效形式為接頭的(de)(de)(de)剛度失效，其外部(bu)表(biao)現型式為泄漏(lou)。壓(ya)力(li)(li)(li)容(rong)器(qi)內部(bu)的(de)(de)(de)介質具有高溫、高壓(ya)的(de)(de)(de)特點，同(tong)時具有易燃(ran)、易爆的(de)(de)(de)特性或(huo)毒性，一旦(dan)產生泄漏(lou)，將發(fa)生嚴重的(de)(de)(de)次(ci)生災害，嚴重威脅壓(ya)力(li)(li)(li)容(rong)器(qi)本(ben)體和(he)周圍設備以及(ji)(ji)人員的(de)(de)(de)安全(quan)。因此容(rong)器(qi)法蘭的(de)(de)(de)設計(ji)和(he)選用應(ying)優先考慮的(de)(de)(de)因素是(shi)整體密封性能(neng)。

  我國(guo)壓(ya)(ya)力容(rong)器法(fa)蘭標(biao)準(zhun)(zhun)自成體系(xi)。最早的(de)壓(ya)(ya)力容(rong)器法(fa)蘭標(biao)準(zhun)(zhun)可(ke)以追溯(su)到20世紀(ji)70年代，當時使用的(de)是由原一機部(bu)、石油部(bu)、化工部(bu)三部(bu)共(gong)同發布的(de)壓(ya)(ya)力容(rong)器法(fa)蘭行業標(biao)準(zhun)(zhun)JB 1157~1164-1973.經過長(chang)期(qi)的(de)試用及(ji)不斷的(de)修訂，目前最新的(de)標(biao)準(zhun)(zhun)為NB/T 47020~47027-2012《壓(ya)(ya)力容(rong)器法(fa)蘭》。

  就法蘭的結構型式和(he)工作原(yuan)理而(er)言，壓力(li)容器法蘭和(he)管(guan)(guan)(guan)(guan)法蘭沒有多(duo)大(da)差異。比較(jiao)明顯的區(qu)別是，壓力(li)容器法蘭規(gui)格較(jiao)大(da)，與(yu)(yu)各類壓力(li)容器連接(jie)使(shi)用；而(er)管(guan)(guan)(guan)(guan)法蘭常常與(yu)(yu)管(guan)(guan)(guan)(guan)子(zi)直(zhi)接(jie)連接(jie)或與(yu)(yu)泵、閥、機(ji)等管(guan)(guan)(guan)(guan)道設備的進出口管(guan)(guan)(guan)(guan)子(zi)連接(jie)使(shi)用。

  壓(ya)(ya)(ya)力(li)容器法(fa)(fa)蘭(lan)(lan)工(gong)作(zuo)原理為：當對法(fa)(fa)蘭(lan)(lan)螺栓(shuan)(shuan)(shuan)施加預緊(jin)力(li)時，螺栓(shuan)(shuan)(shuan)力(li)通過(guo)法(fa)(fa)蘭(lan)(lan)環把墊(dian)(dian)(dian)片(pian)(pian)壓(ya)(ya)(ya)緊(jin)，迫使法(fa)(fa)蘭(lan)(lan)墊(dian)(dian)(dian)片(pian)(pian)產(chan)生壓(ya)(ya)(ya)縮(suo)變(bian)形。當螺栓(shuan)(shuan)(shuan)力(li)達(da)到(dao)(dao)一定數值后，迫使法(fa)(fa)蘭(lan)(lan)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)和墊(dian)(dian)(dian)片(pian)(pian)上的(de)凹凸不(bu)平面(mian)(mian)借助墊(dian)(dian)(dian)片(pian)(pian)變(bian)形而填滿，這就為阻止流體介質泄漏創(chuang)造了初始密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)條件。此(ci)時墊(dian)(dian)(dian)片(pian)(pian)單位有(you)效密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)積上的(de)壓(ya)(ya)(ya)緊(jin)力(li)稱為墊(dian)(dian)(dian)片(pian)(pian)的(de)初始密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)。當設備或管道承受介質壓(ya)(ya)(ya)力(li)后，螺栓(shuan)(shuan)(shuan)受到(dao)(dao)拉伸應力(li)而伸長，法(fa)(fa)蘭(lan)(lan)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)沿著彼此(ci)分離的(de)方向移動，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)與墊(dian)(dian)(dian)片(pian)(pian)之間的(de)壓(ya)(ya)(ya)緊(jin)力(li)下(xia)降(jiang)，墊(dian)(dian)(dian)片(pian)(pian)的(de)壓(ya)(ya)(ya)縮(suo)量減少，預緊(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)下(xia)降(jiang)。如(ru)果這時密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)墊(dian)(dian)(dian)片(pian)(pian)具有(you)足夠的(de)回彈能力(li)，墊(dian)(dian)(dian)片(pian)(pian)的(de)變(bian)形能補償螺栓(shuan)(shuan)(shuan)和密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)的(de)分離值，而使預緊(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)只下(xia)降(jiang)到(dao)(dao)不(bu)小于工(gong)作(zuo)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)，則(ze)法(fa)(fa)蘭(lan)(lan)依然保持(chi)良好(hao)的(de)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)狀態。反之，如(ru)墊(dian)(dian)(dian)片(pian)(pian)的(de)回彈能力(li)不(bu)足，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)下(xia)降(jiang)到(dao)(dao)工(gong)作(zuo)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)比壓(ya)(ya)(ya)以下(xia)，甚至密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)口(kou)重新出現縫隙，則(ze)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)失效。