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)(ding)(ding)油(you)(you)(you)罐(guan)(guan)當(dang)罐(guan)(guan)頂(ding)(ding)(ding)(ding)隨油(you)(you)(you)面下降至罐(guan)(guan)底(di)時(shi)，油(you)(you)(you)罐(guan)(guan)就變為(wei)上(shang)部(bu)敞開的立式圓筒形(xing)容(rong)器，若此時(shi)遇大風，罐(guan)(guan)內(nei)(nei)易(yi)形(xing)成真(zhen)空(kong)，如真(zhen)空(kong)度(du)過大罐(guan)(guan)壁有(you)可能被壓癟，為(wei)此在靠近頂(ding)(ding)(ding)(ding)部(bu)的外(wai)側設置(zhi)抗(kang)風圈。由于罐(guan)(guan)頂(ding)(ding)(ding)(ding)在罐(guan)(guan)內(nei)(nei)上(shang)下浮(fu)動，故罐(guan)(guan)壁板只能采用(yong)對(dui)(dui)接焊接并(bing)且(qie)內(nei)(nei)壁要取(qu)平。浮(fu)頂(ding)(ding)(ding)(ding)油(you)(you)(you)罐(guan)(guan)罐(guan)(guan)頂(ding)(ding)(ding)(ding)與(yu)油(you)(you)(you)面之(zhi)間基(ji)本上(shang)沒有(you)氣(qi)相空(kong)間，油(you)(you)(you)品沒有(you)蒸發(fa)(fa)的條件，因而(er)(er)沒有(you)因環(huan)境(jing)溫度(du)變化而(er)(er)產生的油(you)(you)(you)品損耗(hao)(hao)，也基(ji)本上(shang)消(xiao)除了(le)因收、發(fa)(fa)油(you)(you)(you)而(er)(er)產生的損耗(hao)(hao)，避免(mian)污(wu)染環(huan)境(jing)，減(jian)少發(fa)(fa)生火災的危險(xian)性。所以盡管這種(zhong)油(you)(you)(you)罐(guan)(guan)鋼材耗(hao)(hao)量和安裝費用(yong)比拱(gong)頂(ding)(ding)(ding)(ding)油(you)(you)(you)罐(guan)(guan)大得多，但對(dui)(dui)收發(fa)(fa)油(you)(you)(you)頻繁的油(you)(you)(you)庫、煉油(you)(you)(you)廠原(yuan)油(you)(you)(you)區等仍應(ying)優先選用(yong)，用(yong)于儲存原(yuan)油(you)(you)(you)、汽油(you)(you)(you)及其(qi)他揮發(fa)(fa)性油(you)(you)(you)品。

  浮(fu)(fu)頂(ding)(ding)罐(guan)(guan)的(de)(de)種類(lei)很(hen)多，有單(dan)盤(pan)式(shi)、雙(shuang)(shuang)盤(pan)式(shi)、浮(fu)(fu)子式(shi)等(deng)。常用的(de)(de)單(dan)盤(pan)式(shi)浮(fu)(fu)頂(ding)(ding)罐(guan)(guan)在浮(fu)(fu)頂(ding)(ding)周圍(wei)建(jian)造(zao)環形浮(fu)(fu)船，用隔板(ban)將浮(fu)(fu)船分(fen)隔成若干個不滲漏的(de)(de)船室(shi)，在環形浮(fu)(fu)船范圍(wei)內的(de)(de)面積以單(dan)層(ceng)金(jin)屬(shu)(shu)板(ban)覆蓋(gai)。而雙(shuang)(shuang)盤(pan)式(shi)浮(fu)(fu)頂(ding)(ding)罐(guan)(guan)的(de)(de)浮(fu)(fu)頂(ding)(ding)則是(shi)上、下兩面分(fen)別以金(jin)屬(shu)(shu)板(ban)覆蓋(gai)。不論是(shi)單(dan)盤(pan)浮(fu)(fu)頂(ding)(ding)罐(guan)(guan)還是(shi)雙(shuang)(shuang)盤(pan)浮(fu)(fu)頂(ding)(ding)罐(guan)(guan)，浮(fu)(fu)盤(pan)上面都(dou)安裝有梯子、平(ping)臺和欄桿。建(jian)造(zao)浮(fu)(fu)頂(ding)(ding)的(de)(de)金(jin)屬(shu)(shu)材料有碳鋼和鋁(lv)合(he)金(jin)兩種，目前(qian)，碳鋼材料的(de)(de)浮(fu)(fu)頂(ding)(ding)已逐(zhu)漸(jian)被(bei)鋁(lv)合(he)金(jin)浮(fu)(fu)頂(ding)(ding)所替代。浮(fu)(fu)頂(ding)(ding)一(yi)般在專門的(de)(de)制(zhi)造(zao)廠建(jian)造(zao)，作為成品部件供貨。