不銹鋼(gang)法蘭墊片的主要(yao)參(can)數(shu)包(bao)括墊片的有效密封寬度、墊片的性能參(can)數(shu)、墊片公稱(cheng)通徑或(huo)公稱(cheng)尺寸及(ji)墊片公稱(cheng)壓力。


一、不銹(xiu)鋼(gang)法蘭墊片的(de)有效密封(feng)寬度


  法蘭密封接頭中,墊片的有效密封寬度是作為計算法蘭螺栓載荷必不可少的一個特性參數,通常用符號b表示,其單位以mm計。不銹鋼法蘭墊片的有效密封寬度與墊片基本密封寬度有關。墊片基本密封寬度用符號b0表示,其單位以mm計。


 當選定墊片尺寸后,可按表11-1確定墊片接觸面寬度和墊片基本密封寬度b0。墊片接觸面寬度以符號N表示,其單位以mm計。墊片基本密封寬度b0見表11-1。




二(er)、不(bu)銹鋼法蘭墊片性能參數(shu)


 不(bu)銹鋼法(fa)(fa)(fa)蘭墊(dian)片的(de)(de)性能參數(shu)是指規(gui)(gui)范(fan)設計(ji)法(fa)(fa)(fa)(即ASME《鍋爐和壓力容器規(gui)(gui)范(fan)》中(zhong)所推薦(jian)的(de)(de)螺栓法(fa)(fa)(fa)蘭連接的(de)(de)規(gui)(gui)范(fan)設計(ji)法(fa)(fa)(fa))中(zhong)所涉(she)及的(de)(de)“y”及“m”兩個(ge)密封(feng)系(xi)數(shu)。


 1. 不銹鋼法(fa)蘭墊片(pian)最小預緊比壓 


   在(zai)法蘭(lan)密封接頭中,壓(ya)(ya)緊(jin)墊(dian)(dian)片(pian)(pian)所需(xu)的(de)(de)力使墊(dian)(dian)片(pian)(pian)材料產(chan)生變(bian)形從而填滿法蘭(lan)密封面間的(de)(de)微間隙。壓(ya)(ya)緊(jin)墊(dian)(dian)片(pian)(pian)所需(xu)的(de)(de)最(zui)小應(ying)力稱為墊(dian)(dian)片(pian)(pian)最(zui)小預緊(jin)比壓(ya)(ya),通常(chang)以(yi)符號y表示。墊(dian)(dian)片(pian)(pian)最(zui)小預緊(jin)比壓(ya)(ya)是指在(zai)安裝過程(cheng)中沒有內壓(ya)(ya)的(de)(de)情況下,墊(dian)(dian)片(pian)(pian)接觸(chu)面積上的(de)(de)壓(ya)(ya)應(ying)力,其表達式為:


式 1.jpg



 2. 不銹鋼法蘭墊片系(xi)數(shu) 


   壓(ya)緊墊(dian)片時(shi),螺栓伸(shen)長,當介(jie)質(zhi)壓(ya)力作用后,螺栓由于(yu)受(shou)介(jie)質(zhi)壓(ya)力作用產生的載荷(he)而更加(jia)伸(shen)長,致使兩密封法蘭(lan)面之間(jian)的間(jian)隙增大,使墊(dian)片的應力降低(di),產生泄漏。


   為(wei)了保(bao)證工(gong)作狀(zhuang)態(tai)下的(de)密封性能(neng),墊片上應(ying)有一定的(de)比壓(ya),即工(gong)作狀(zhuang)態(tai)下的(de)壓(ya)緊比壓(ya),或(huo)稱殘余壓(ya)緊應(ying)力(li),以符號(hao)y1表(biao)示。墊片系數定義為(wei)工(gong)作狀(zhuang)態(tai)下墊片上的(de)殘余壓(ya)緊應(ying)力(li)與介質壓(ya)力(li)之比值,其表(biao)達(da)式為(wei):


式 2.jpg


  不銹鋼法(fa)蘭墊(dian)(dian)片(pian)最小預緊比壓和(he)墊(dian)(dian)片(pian)系數(shu)由實驗確定,它們是僅與墊(dian)(dian)片(pian)材(cai)料及(ji)法(fa)蘭密封面形式有關的特性(xing)參數(shu)。規范墊(dian)(dian)片(pian)特性(xing)參數(shu)或(huo)墊(dian)(dian)片(pian)性(xing)能(neng)參數(shu)m及(ji)y值見表(biao)11-2。



三、不銹鋼法(fa)蘭墊片(pian)公(gong)稱通(tong)徑(jing)及公(gong)稱壓力(li)


  公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)及(ji)公(gong)(gong)稱(cheng)(cheng)壓力(li)是(shi)(shi)(shi)(shi)(shi)墊片(pian)的配套(tao)參(can)數(shu)。公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)或公(gong)(gong)稱(cheng)(cheng)尺(chi)寸(cun)(見(jian)GB/T 1047-2005)是(shi)(shi)(shi)(shi)(shi)管(guan)路(lu)(lu)附件的一(yi)個基(ji)本參(can)數(shu),它并不是(shi)(shi)(shi)(shi)(shi)某(mou)一(yi)個實(shi)際結(jie)構尺(chi)寸(cun),而僅(jin)(jin)僅(jin)(jin)是(shi)(shi)(shi)(shi)(shi)與(yu)制造(zao)尺(chi)寸(cun)密切相(xiang)關的經過(guo)圓整后(hou)的一(yi)個名義尺(chi)寸(cun),僅(jin)(jin)作為一(yi)種(zhong)(zhong)標(biao)志,其標(biao)記方法(fa)是(shi)(shi)(shi)(shi)(shi)在(zai)代(dai)號(hao)“DN”后(hou)緊跟(gen)著(zhu)一(yi)個適當(dang)的數(shu)字。墊片(pian)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)與(yu)法(fa)蘭(lan)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)相(xiang)同;公(gong)(gong)稱(cheng)(cheng)壓力(li)(見(jian)GB/T 1048-2005)是(shi)(shi)(shi)(shi)(shi)指與(yu)管(guan)路(lu)(lu)附件(如法(fa)蘭(lan)、管(guan)件、閥門(men)等)機械強度有關的設計給(gei)定壓力(li),是(shi)(shi)(shi)(shi)(shi)一(yi)個經過(guo)圓整后(hou)的名義值,也是(shi)(shi)(shi)(shi)(shi)僅(jin)(jin)作為一(yi)種(zhong)(zhong)標(biao)志,其標(biao)記方法(fa)是(shi)(shi)(shi)(shi)(shi)在(zai)代(dai)號(hao)“PN”后(hou)緊跟(gen)一(yi)個適當(dang)的數(shu)字。墊片(pian)公(gong)(gong)稱(cheng)(cheng)壓力(li)亦與(yu)法(fa)蘭(lan)公(gong)(gong)稱(cheng)(cheng)壓力(li)相(xiang)同。