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)油(you)(you)(you)(you)罐(guan)當(dang)罐(guan)頂(ding)隨油(you)(you)(you)(you)面下(xia)降(jiang)至罐(guan)底時(shi)，油(you)(you)(you)(you)罐(guan)就(jiu)變為(wei)上(shang)部(bu)敞開的(de)立(li)式圓筒形容器，若此時(shi)遇大風，罐(guan)內易(yi)形成真(zhen)空(kong)，如(ru)真(zhen)空(kong)度過大罐(guan)壁有(you)可能被壓(ya)癟，為(wei)此在(zai)靠近頂(ding)部(bu)的(de)外(wai)側(ce)設(she)置抗風圈。由于罐(guan)頂(ding)在(zai)罐(guan)內上(shang)下(xia)浮(fu)動，故(gu)罐(guan)壁板只能采用(yong)對(dui)接焊(han)接并且內壁要取平。浮(fu)頂(ding)油(you)(you)(you)(you)罐(guan)罐(guan)頂(ding)與油(you)(you)(you)(you)面之間(jian)基本上(shang)沒有(you)氣相空(kong)間(jian)，油(you)(you)(you)(you)品沒有(you)蒸(zheng)發(fa)的(de)條件，因(yin)而沒有(you)因(yin)環境溫度變化而產生(sheng)的(de)油(you)(you)(you)(you)品損(sun)耗(hao)，也基本上(shang)消除(chu)了因(yin)收、發(fa)油(you)(you)(you)(you)而產生(sheng)的(de)損(sun)耗(hao)，避免污染環境，減少發(fa)生(sheng)火災的(de)危險性。所(suo)以盡管這種油(you)(you)(you)(you)罐(guan)鋼材耗(hao)量和安裝費用(yong)比拱頂(ding)油(you)(you)(you)(you)罐(guan)大得(de)多(duo)，但對(dui)收發(fa)油(you)(you)(you)(you)頻繁的(de)油(you)(you)(you)(you)庫、煉油(you)(you)(you)(you)廠原油(you)(you)(you)(you)區等(deng)仍應優先選用(yong)，用(yong)于儲(chu)存原油(you)(you)(you)(you)、汽油(you)(you)(you)(you)及其他揮發(fa)性油(you)(you)(you)(you)品。

  浮(fu)(fu)頂(ding)(ding)(ding)(ding)罐(guan)(guan)的(de)(de)(de)種(zhong)類很多，有(you)單(dan)盤(pan)(pan)式、雙(shuang)盤(pan)(pan)式、浮(fu)(fu)子式等。常用的(de)(de)(de)單(dan)盤(pan)(pan)式浮(fu)(fu)頂(ding)(ding)(ding)(ding)罐(guan)(guan)在浮(fu)(fu)頂(ding)(ding)(ding)(ding)周圍建(jian)造(zao)環(huan)(huan)形浮(fu)(fu)船(chuan)，用隔(ge)板將浮(fu)(fu)船(chuan)分隔(ge)成若干個不滲漏的(de)(de)(de)船(chuan)室(shi)，在環(huan)(huan)形浮(fu)(fu)船(chuan)范圍內的(de)(de)(de)面積以單(dan)層金(jin)屬(shu)板覆(fu)蓋。而雙(shuang)盤(pan)(pan)式浮(fu)(fu)頂(ding)(ding)(ding)(ding)罐(guan)(guan)的(de)(de)(de)浮(fu)(fu)頂(ding)(ding)(ding)(ding)則(ze)是上、下兩(liang)面分別以金(jin)屬(shu)板覆(fu)蓋。不論是單(dan)盤(pan)(pan)浮(fu)(fu)頂(ding)(ding)(ding)(ding)罐(guan)(guan)還(huan)是雙(shuang)盤(pan)(pan)浮(fu)(fu)頂(ding)(ding)(ding)(ding)罐(guan)(guan)，浮(fu)(fu)盤(pan)(pan)上面都(dou)安裝有(you)梯子、平臺和(he)欄桿。建(jian)造(zao)浮(fu)(fu)頂(ding)(ding)(ding)(ding)的(de)(de)(de)金(jin)屬(shu)材(cai)料(liao)(liao)有(you)碳(tan)鋼和(he)鋁合(he)金(jin)兩(liang)種(zhong)，目前，碳(tan)鋼材(cai)料(liao)(liao)的(de)(de)(de)浮(fu)(fu)頂(ding)(ding)(ding)(ding)已逐漸被鋁合(he)金(jin)浮(fu)(fu)頂(ding)(ding)(ding)(ding)所替代。浮(fu)(fu)頂(ding)(ding)(ding)(ding)一般(ban)在專門(men)的(de)(de)(de)制造(zao)廠建(jian)造(zao)，作為成品部件(jian)供貨。