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)(fu)頂(ding)油(you)(you)(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)當罐(guan)(guan)(guan)(guan)頂(ding)隨油(you)(you)(you)(you)(you)(you)(you)面下降至罐(guan)(guan)(guan)(guan)底時，油(you)(you)(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)就(jiu)變為上(shang)部(bu)敞開的(de)(de)立式圓筒形容器，若此時遇(yu)大(da)風，罐(guan)(guan)(guan)(guan)內(nei)(nei)易形成(cheng)真(zhen)(zhen)空，如真(zhen)(zhen)空度(du)過大(da)罐(guan)(guan)(guan)(guan)壁(bi)有可能(neng)被壓癟(bie)，為此在靠近頂(ding)部(bu)的(de)(de)外(wai)側(ce)設置抗風圈。由于罐(guan)(guan)(guan)(guan)頂(ding)在罐(guan)(guan)(guan)(guan)內(nei)(nei)上(shang)下浮(fu)(fu)動，故罐(guan)(guan)(guan)(guan)壁(bi)板只能(neng)采用(yong)對(dui)接焊(han)接并且內(nei)(nei)壁(bi)要取平。浮(fu)(fu)頂(ding)油(you)(you)(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)罐(guan)(guan)(guan)(guan)頂(ding)與油(you)(you)(you)(you)(you)(you)(you)面之(zhi)間基本(ben)上(shang)沒有氣相(xiang)空間，油(you)(you)(you)(you)(you)(you)(you)品(pin)沒有蒸(zheng)發(fa)(fa)的(de)(de)條件(jian)，因而沒有因環境溫度(du)變化而產生的(de)(de)油(you)(you)(you)(you)(you)(you)(you)品(pin)損耗(hao)，也基本(ben)上(shang)消除了因收、發(fa)(fa)油(you)(you)(you)(you)(you)(you)(you)而產生的(de)(de)損耗(hao)，避(bi)免(mian)污(wu)染(ran)環境，減少(shao)發(fa)(fa)生火災的(de)(de)危險性(xing)。所以盡管(guan)這種油(you)(you)(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)鋼材耗(hao)量和(he)安裝費用(yong)比拱頂(ding)油(you)(you)(you)(you)(you)(you)(you)罐(guan)(guan)(guan)(guan)大(da)得多，但對(dui)收發(fa)(fa)油(you)(you)(you)(you)(you)(you)(you)頻(pin)繁的(de)(de)油(you)(you)(you)(you)(you)(you)(you)庫(ku)、煉油(you)(you)(you)(you)(you)(you)(you)廠原(yuan)(yuan)油(you)(you)(you)(you)(you)(you)(you)區等(deng)仍應優先選(xuan)用(yong)，用(yong)于儲存原(yuan)(yuan)油(you)(you)(you)(you)(you)(you)(you)、汽油(you)(you)(you)(you)(you)(you)(you)及其他揮(hui)發(fa)(fa)性(xing)油(you)(you)(you)(you)(you)(you)(you)品(pin)。

  浮(fu)(fu)頂(ding)罐(guan)(guan)(guan)的(de)種類很多，有單盤(pan)(pan)(pan)式(shi)、雙(shuang)(shuang)盤(pan)(pan)(pan)式(shi)、浮(fu)(fu)子式(shi)等。常用的(de)單盤(pan)(pan)(pan)式(shi)浮(fu)(fu)頂(ding)罐(guan)(guan)(guan)在浮(fu)(fu)頂(ding)周圍建(jian)造環形(xing)浮(fu)(fu)船(chuan)，用隔(ge)板(ban)(ban)將浮(fu)(fu)船(chuan)分隔(ge)成(cheng)若干個不(bu)滲(shen)漏的(de)船(chuan)室，在環形(xing)浮(fu)(fu)船(chuan)范圍內的(de)面(mian)積以單層金(jin)(jin)屬(shu)板(ban)(ban)覆蓋。而雙(shuang)(shuang)盤(pan)(pan)(pan)式(shi)浮(fu)(fu)頂(ding)罐(guan)(guan)(guan)的(de)浮(fu)(fu)頂(ding)則是(shi)上、下兩面(mian)分別(bie)以金(jin)(jin)屬(shu)板(ban)(ban)覆蓋。不(bu)論(lun)是(shi)單盤(pan)(pan)(pan)浮(fu)(fu)頂(ding)罐(guan)(guan)(guan)還是(shi)雙(shuang)(shuang)盤(pan)(pan)(pan)浮(fu)(fu)頂(ding)罐(guan)(guan)(guan)，浮(fu)(fu)盤(pan)(pan)(pan)上面(mian)都安裝(zhuang)有梯子、平臺(tai)和(he)欄桿。建(jian)造浮(fu)(fu)頂(ding)的(de)金(jin)(jin)屬(shu)材料(liao)有碳(tan)鋼和(he)鋁合金(jin)(jin)兩種，目前，碳(tan)鋼材料(liao)的(de)浮(fu)(fu)頂(ding)已逐漸(jian)被(bei)鋁合金(jin)(jin)浮(fu)(fu)頂(ding)所替代。浮(fu)(fu)頂(ding)一般(ban)在專(zhuan)門的(de)制造廠(chang)建(jian)造，作(zuo)為成(cheng)品部件供貨(huo)。