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。

  浮頂(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)當罐(guan)(guan)(guan)頂(ding)隨油(you)(you)(you)(you)(you)面下降至罐(guan)(guan)(guan)底時，油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)就變(bian)為上(shang)部敞開(kai)的立式(shi)圓筒形容器，若(ruo)此時遇大(da)風，罐(guan)(guan)(guan)內易(yi)形成真(zhen)空(kong)，如真(zhen)空(kong)度(du)過大(da)罐(guan)(guan)(guan)壁有(you)(you)(you)可能被壓癟，為此在靠近頂(ding)部的外側(ce)設(she)置抗風圈。由(you)于(yu)罐(guan)(guan)(guan)頂(ding)在罐(guan)(guan)(guan)內上(shang)下浮動，故(gu)罐(guan)(guan)(guan)壁板只能采用(yong)對(dui)接(jie)焊接(jie)并且內壁要(yao)取平(ping)。浮頂(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)罐(guan)(guan)(guan)頂(ding)與油(you)(you)(you)(you)(you)面之間(jian)(jian)基本上(shang)沒有(you)(you)(you)氣相空(kong)間(jian)(jian)，油(you)(you)(you)(you)(you)品沒有(you)(you)(you)蒸(zheng)發的條件，因而(er)沒有(you)(you)(you)因環境溫(wen)度(du)變(bian)化而(er)產生的油(you)(you)(you)(you)(you)品損(sun)(sun)耗，也基本上(shang)消除了因收、發油(you)(you)(you)(you)(you)而(er)產生的損(sun)(sun)耗，避免(mian)污(wu)染環境，減少發生火災的危險性。所以盡管(guan)這種油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)鋼材耗量(liang)和安裝費用(yong)比拱頂(ding)油(you)(you)(you)(you)(you)罐(guan)(guan)(guan)大(da)得多(duo)，但對(dui)收發油(you)(you)(you)(you)(you)頻繁的油(you)(you)(you)(you)(you)庫(ku)、煉油(you)(you)(you)(you)(you)廠原(yuan)油(you)(you)(you)(you)(you)區等仍應優先選用(yong)，用(yong)于(yu)儲存原(yuan)油(you)(you)(you)(you)(you)、汽油(you)(you)(you)(you)(you)及其他(ta)揮發性油(you)(you)(you)(you)(you)品。

  浮(fu)(fu)(fu)頂(ding)罐(guan)(guan)的(de)(de)種類很多，有(you)單盤式(shi)、雙盤式(shi)、浮(fu)(fu)(fu)子(zi)式(shi)等。常用的(de)(de)單盤式(shi)浮(fu)(fu)(fu)頂(ding)罐(guan)(guan)在浮(fu)(fu)(fu)頂(ding)周(zhou)圍建(jian)造環(huan)形浮(fu)(fu)(fu)船(chuan)，用隔(ge)板將(jiang)浮(fu)(fu)(fu)船(chuan)分(fen)隔(ge)成(cheng)若干個不滲(shen)漏的(de)(de)船(chuan)室，在環(huan)形浮(fu)(fu)(fu)船(chuan)范圍內的(de)(de)面積以(yi)單層金(jin)(jin)屬板覆蓋。而雙盤式(shi)浮(fu)(fu)(fu)頂(ding)罐(guan)(guan)的(de)(de)浮(fu)(fu)(fu)頂(ding)則是(shi)上、下(xia)兩(liang)面分(fen)別以(yi)金(jin)(jin)屬板覆蓋。不論是(shi)單盤浮(fu)(fu)(fu)頂(ding)罐(guan)(guan)還是(shi)雙盤浮(fu)(fu)(fu)頂(ding)罐(guan)(guan)，浮(fu)(fu)(fu)盤上面都(dou)安裝有(you)梯子(zi)、平臺和(he)欄桿。建(jian)造浮(fu)(fu)(fu)頂(ding)的(de)(de)金(jin)(jin)屬材料有(you)碳鋼和(he)鋁合(he)金(jin)(jin)兩(liang)種，目前，碳鋼材料的(de)(de)浮(fu)(fu)(fu)頂(ding)已(yi)逐漸(jian)被(bei)鋁合(he)金(jin)(jin)浮(fu)(fu)(fu)頂(ding)所替代。浮(fu)(fu)(fu)頂(ding)一般在專門的(de)(de)制造廠建(jian)造，作為成(cheng)品(pin)部件供(gong)貨。