法蘭接頭是由法蘭、密封墊片及連接螺栓三種元件組成的一個承壓管道連接件。在法蘭密封接頭中，墊片是最主要的密封元件。對于非金屬墊片來說，法蘭接頭的密封是通過擰緊螺栓，使法蘭與墊片接觸表面及其墊片內部造成較大的壓緊應力，從而一方面使墊片表面與法蘭表面緊密貼合以填滿法蘭表面的微間隙，另一方面減小墊片材料的孔隙率，即減小被密封流體的泄漏通道，從而實現法蘭接頭的密封。由于任何制造或加工方法都不可能形成絕對光滑的理想表面，也不可能實現密封面間的完全嵌合以及密封件本身孔隙的完全阻塞，所以在相互接觸的密封面間和密封墊片內部總是存在著微小的間隙或通道。因而，對墊片密封來說，泄漏總是不可避免的。當介質以一定的壓力通過螺栓法蘭連接時，總會在密封點處出現泄漏。

  法蘭(lan)接頭(tou)的(de)(de)(de)密(mi)封失效形式主要(yao)表現為泄(xie)漏。泄(xie)漏輕則造成能源(yuan)、原材料(liao)的(de)(de)(de)大量浪費，重則導致設備報廢、停工停產、人員傷亡和(he)嚴(yan)重的(de)(de)(de)環境污染。隨著現代石油、化工、原子(zi)能、航天及深(shen)海技術(shu)的(de)(de)(de)迅速發展，對管道及其裝置的(de)(de)(de)密(mi)封提出了更嚴(yan)格的(de)(de)(de)要(yao)求，因而密(mi)封墊(dian)片的(de)(de)(de)地位(wei)更加重要(yao)。

  在墊(dian)片密(mi)封(feng)(feng)的(de)法蘭(lan)接頭(tou)中，雖(sui)然泄(xie)漏無法避免，但可(ke)以控制在一定的(de)范圍內。墊(dian)片密(mi)封(feng)(feng)的(de)可(ke)靠(kao)性(xing)與連接結(jie)構的(de)形式、介質特性(xing)、工況條(tiao)件(jian)等諸多因(yin)素有關(guan)，而且最主要(yao)的(de)是與所采用的(de)密(mi)封(feng)(feng)墊(dian)片材料和其結(jie)構有關(guan)。影響墊(dian)片密(mi)封(feng)(feng)的(de)因(yin)素很多，至(zhi)今還是一個未能定量的(de)問題，因(yin)此研究墊(dian)片密(mi)封(feng)(feng)的(de)工作，至(zhi)今仍(reng)然是工業界普(pu)遍關(guan)注的(de)問題。

  本篇就墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)基礎知(zhi)識、墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)結構及(ji)其標準(zhun)進行描述，共4章組成，內(nei)容包括墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)的(de)一(yi)般結構型式、種類、參數和設(she)計選(xuan)用(yong)；非(fei)金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)平墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)（含(han)非(fei)金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)軟(ruan)墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)及(ji)聚四(si)氟乙烯包覆墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)）；金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)復(fu)合(he)墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)（含(han)纏繞式墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)、金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)包覆墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)、金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)沖齒板柔(rou)性石墨(mo)復(fu)合(he)墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)、柔(rou)性石墨(mo)金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)波(bo)齒復(fu)合(he)墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)）及(ji)金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)（含(han)金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)環形墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)、金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)齒形墊(dian)(dian)(dian)(dian)(dian)片(pian)(pian)(pian)(pian)(pian)及(ji)R型、RX型及(ji)BX型專(zhuan)用(yong)自緊密封金(jin)(jin)(jin)屬(shu)(shu)(shu)(shu)環墊(dian)(dian)(dian)(dian)(dian)）等。