壓力(li)(li)(li)容(rong)器(qi)(qi)法(fa)蘭是壓力(li)(li)(li)容(rong)器(qi)(qi)的(de)常用(yong)部件(jian)，是連接(jie)各(ge)種壓力(li)(li)(li)容(rong)器(qi)(qi)部件(jian)的(de)基本元(yuan)件(jian)，廣泛地用(yong)于石油、石化、電力(li)(li)(li)、原子能(neng)(neng)、輕工等領域。對于容(rong)器(qi)(qi)而(er)言，應該是一個組件(jian)，包括法(fa)蘭、墊片和連接(jie)螺(luo)栓或(huo)螺(luo)柱以及螺(luo)母(mu)，其作用(yong)是使(shi)不同(tong)(tong)的(de)受壓元(yuan)件(jian)組合(he)在(zai)一起，同(tong)(tong)時保證連接(jie)部位不發生泄(xie)漏(lou)(lou)。法(fa)蘭連接(jie)的(de)主要失(shi)效(xiao)(xiao)形式為接(jie)頭的(de)剛(gang)度失(shi)效(xiao)(xiao)，其外部表現型式為泄(xie)漏(lou)(lou)。壓力(li)(li)(li)容(rong)器(qi)(qi)內部的(de)介質具有高(gao)溫(wen)、高(gao)壓的(de)特(te)點，同(tong)(tong)時具有易燃、易爆的(de)特(te)性或(huo)毒性，一旦產生泄(xie)漏(lou)(lou)，將發生嚴(yan)重(zhong)的(de)次生災(zai)害，嚴(yan)重(zhong)威脅壓力(li)(li)(li)容(rong)器(qi)(qi)本體和周(zhou)圍設(she)(she)備以及人員的(de)安全。因(yin)此容(rong)器(qi)(qi)法(fa)蘭的(de)設(she)(she)計和選用(yong)應優先考慮的(de)因(yin)素是整(zheng)體密封性能(neng)(neng)。

  我國壓力(li)容器(qi)法(fa)蘭標準(zhun)自成體系。最(zui)早(zao)的(de)壓力(li)容器(qi)法(fa)蘭標準(zhun)可以追(zhui)溯(su)到20世(shi)紀70年代(dai)，當時使用(yong)的(de)是由(you)原一機部、石油(you)部、化工(gong)部三部共同發布的(de)壓力(li)容器(qi)法(fa)蘭行業標準(zhun)JB 1157~1164-1973.經過長期(qi)的(de)試用(yong)及不斷的(de)修訂，目前最(zui)新的(de)標準(zhun)為(wei)NB/T 47020~47027-2012《壓力(li)容器(qi)法(fa)蘭》。

  就法蘭的結構型式和(he)工作原理而(er)言，壓力(li)容(rong)器法蘭和(he)管法蘭沒有(you)多大差異(yi)。比較(jiao)明顯的區別是，壓力(li)容(rong)器法蘭規(gui)格較(jiao)大，與各類壓力(li)容(rong)器連(lian)接使(shi)用；而(er)管法蘭常常與管子(zi)直(zhi)接連(lian)接或(huo)與泵、閥、機等管道設備的進出口管子(zi)連(lian)接使(shi)用。

  壓(ya)(ya)(ya)力(li)(li)(li)容器法(fa)蘭(lan)工作原理為(wei)：當(dang)對法(fa)蘭(lan)螺(luo)栓施加預(yu)(yu)緊(jin)(jin)(jin)力(li)(li)(li)時(shi)，螺(luo)栓力(li)(li)(li)通過法(fa)蘭(lan)環把墊(dian)(dian)(dian)片(pian)(pian)壓(ya)(ya)(ya)緊(jin)(jin)(jin)，迫使法(fa)蘭(lan)墊(dian)(dian)(dian)片(pian)(pian)產生(sheng)壓(ya)(ya)(ya)縮變形。當(dang)螺(luo)栓力(li)(li)(li)達到(dao)一定數值后，迫使法(fa)蘭(lan)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)面(mian)(mian)和墊(dian)(dian)(dian)片(pian)(pian)上(shang)的(de)凹凸不(bu)平(ping)面(mian)(mian)借助墊(dian)(dian)(dian)片(pian)(pian)變形而填(tian)滿，這就為(wei)阻止流體介(jie)質泄(xie)漏創(chuang)造了初(chu)(chu)始(shi)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)條件。此時(shi)墊(dian)(dian)(dian)片(pian)(pian)單位有效(xiao)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)面(mian)(mian)積上(shang)的(de)壓(ya)(ya)(ya)緊(jin)(jin)(jin)力(li)(li)(li)稱(cheng)為(wei)墊(dian)(dian)(dian)片(pian)(pian)的(de)初(chu)(chu)始(shi)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)。當(dang)設備(bei)或(huo)管道承受介(jie)質壓(ya)(ya)(ya)力(li)(li)(li)后，螺(luo)栓受到(dao)拉伸應力(li)(li)(li)而伸長(chang)，法(fa)蘭(lan)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)面(mian)(mian)沿著(zhu)彼此分(fen)離(li)的(de)方向(xiang)移(yi)動，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)面(mian)(mian)與(yu)墊(dian)(dian)(dian)片(pian)(pian)之間的(de)壓(ya)(ya)(ya)緊(jin)(jin)(jin)力(li)(li)(li)下(xia)(xia)降，墊(dian)(dian)(dian)片(pian)(pian)的(de)壓(ya)(ya)(ya)縮量減(jian)少，預(yu)(yu)緊(jin)(jin)(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)下(xia)(xia)降。如果這時(shi)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)墊(dian)(dian)(dian)片(pian)(pian)具有足夠的(de)回(hui)彈(dan)能(neng)力(li)(li)(li)，墊(dian)(dian)(dian)片(pian)(pian)的(de)變形能(neng)補償(chang)螺(luo)栓和密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)面(mian)(mian)的(de)分(fen)離(li)值，而使預(yu)(yu)緊(jin)(jin)(jin)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)只下(xia)(xia)降到(dao)不(bu)小于工作密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)，則法(fa)蘭(lan)依然保持良(liang)好的(de)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)狀(zhuang)態。反(fan)之，如墊(dian)(dian)(dian)片(pian)(pian)的(de)回(hui)彈(dan)能(neng)力(li)(li)(li)不(bu)足，密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)下(xia)(xia)降到(dao)工作密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)比(bi)(bi)壓(ya)(ya)(ya)以下(xia)(xia)，甚至(zhi)密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)口(kou)重新出現縫(feng)隙(xi)，則密(mi)(mi)(mi)(mi)(mi)封(feng)(feng)失(shi)效(xiao)。