浮頂油罐上部是敞開的，罐頂只是漂浮在罐內油面上隨油面的升降而升降的浮盤，浮盤外徑比罐壁內徑小400～600mm，用以裝設密封裝置，以防止這一環狀間隙中的油品產生蒸發損壞，同時防止風沙雨雪等污染油品。密封裝置形式很多，常用的有彈性填料密封或管式密封。

  浮(fu)頂(ding)(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)當罐(guan)(guan)(guan)(guan)頂(ding)(ding)隨(sui)油(you)(you)(you)(you)(you)面下降至(zhi)罐(guan)(guan)(guan)(guan)底時，油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)就變為上部敞開(kai)的(de)立式圓筒形容器，若此(ci)時遇大風(feng)，罐(guan)(guan)(guan)(guan)內易形成(cheng)真空(kong)，如真空(kong)度過大罐(guan)(guan)(guan)(guan)壁有可能被壓癟，為此(ci)在(zai)靠近頂(ding)(ding)部的(de)外側(ce)設置(zhi)抗風(feng)圈。由于(yu)罐(guan)(guan)(guan)(guan)頂(ding)(ding)在(zai)罐(guan)(guan)(guan)(guan)內上下浮(fu)動(dong)，故罐(guan)(guan)(guan)(guan)壁板只能采用(yong)對接(jie)焊接(jie)并且內壁要(yao)取(qu)平。浮(fu)頂(ding)(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)罐(guan)(guan)(guan)(guan)頂(ding)(ding)與油(you)(you)(you)(you)(you)面之間基(ji)本上沒(mei)有氣(qi)相空(kong)間，油(you)(you)(you)(you)(you)品沒(mei)有蒸發的(de)條件，因而(er)(er)沒(mei)有因環(huan)境溫度變化而(er)(er)產(chan)生(sheng)的(de)油(you)(you)(you)(you)(you)品損(sun)耗(hao)(hao)，也(ye)基(ji)本上消除了因收、發油(you)(you)(you)(you)(you)而(er)(er)產(chan)生(sheng)的(de)損(sun)耗(hao)(hao)，避免污(wu)染環(huan)境，減少(shao)發生(sheng)火災(zai)的(de)危險性(xing)。所以盡管這種油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)鋼材耗(hao)(hao)量和安裝費用(yong)比拱頂(ding)(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)大得多，但對收發油(you)(you)(you)(you)(you)頻(pin)繁的(de)油(you)(you)(you)(you)(you)庫、煉(lian)油(you)(you)(you)(you)(you)廠原油(you)(you)(you)(you)(you)區(qu)等仍應(ying)優先選用(yong)，用(yong)于(yu)儲存原油(you)(you)(you)(you)(you)、汽油(you)(you)(you)(you)(you)及其他揮發性(xing)油(you)(you)(you)(you)(you)品。

  浮(fu)頂罐(guan)的(de)種(zhong)類很多，有單盤(pan)(pan)式(shi)(shi)、雙(shuang)盤(pan)(pan)式(shi)(shi)、浮(fu)子式(shi)(shi)等。常用的(de)單盤(pan)(pan)式(shi)(shi)浮(fu)頂罐(guan)在(zai)浮(fu)頂周圍建(jian)造(zao)環形(xing)浮(fu)船，用隔板將浮(fu)船分隔成若干(gan)個(ge)不滲漏的(de)船室，在(zai)環形(xing)浮(fu)船范(fan)圍內的(de)面(mian)(mian)積以單層金(jin)屬板覆蓋。而雙(shuang)盤(pan)(pan)式(shi)(shi)浮(fu)頂罐(guan)的(de)浮(fu)頂則是(shi)(shi)上、下兩面(mian)(mian)分別以金(jin)屬板覆蓋。不論是(shi)(shi)單盤(pan)(pan)浮(fu)頂罐(guan)還是(shi)(shi)雙(shuang)盤(pan)(pan)浮(fu)頂罐(guan)，浮(fu)盤(pan)(pan)上面(mian)(mian)都(dou)安裝有梯子、平臺和欄桿。建(jian)造(zao)浮(fu)頂的(de)金(jin)屬材料有碳(tan)鋼(gang)和鋁合金(jin)兩種(zhong)，目(mu)前，碳(tan)鋼(gang)材料的(de)浮(fu)頂已逐漸被鋁合金(jin)浮(fu)頂所替代。浮(fu)頂一般在(zai)專門的(de)制造(zao)廠建(jian)造(zao)，作為成品部件供貨。