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)罐(guan)(guan)(guan)(guan)(guan)當罐(guan)(guan)(guan)(guan)(guan)頂(ding)隨油(you)(you)(you)面下(xia)降至(zhi)罐(guan)(guan)(guan)(guan)(guan)底時，油(you)(you)(you)罐(guan)(guan)(guan)(guan)(guan)就變為上(shang)部敞開的立(li)式(shi)圓(yuan)筒形(xing)容器，若(ruo)此時遇(yu)大(da)(da)風，罐(guan)(guan)(guan)(guan)(guan)內易形(xing)成真空(kong)(kong)，如真空(kong)(kong)度(du)過大(da)(da)罐(guan)(guan)(guan)(guan)(guan)壁有(you)可能被壓(ya)癟，為此在靠近頂(ding)部的外側設置(zhi)抗風圈。由(you)于罐(guan)(guan)(guan)(guan)(guan)頂(ding)在罐(guan)(guan)(guan)(guan)(guan)內上(shang)下(xia)浮(fu)動(dong)，故罐(guan)(guan)(guan)(guan)(guan)壁板只(zhi)能采(cai)用對(dui)(dui)接焊接并且內壁要(yao)取平(ping)。浮(fu)頂(ding)油(you)(you)(you)罐(guan)(guan)(guan)(guan)(guan)罐(guan)(guan)(guan)(guan)(guan)頂(ding)與油(you)(you)(you)面之間(jian)基(ji)本上(shang)沒有(you)氣(qi)相(xiang)空(kong)(kong)間(jian)，油(you)(you)(you)品沒有(you)蒸發的條件，因(yin)而沒有(you)因(yin)環(huan)境(jing)溫(wen)度(du)變化而產(chan)(chan)生(sheng)的油(you)(you)(you)品損耗，也(ye)基(ji)本上(shang)消除(chu)了因(yin)收(shou)、發油(you)(you)(you)而產(chan)(chan)生(sheng)的損耗，避免污染(ran)環(huan)境(jing)，減少發生(sheng)火災(zai)的危險性。所以盡(jin)管這(zhe)種油(you)(you)(you)罐(guan)(guan)(guan)(guan)(guan)鋼材耗量和安裝費用比拱頂(ding)油(you)(you)(you)罐(guan)(guan)(guan)(guan)(guan)大(da)(da)得多(duo)，但(dan)對(dui)(dui)收(shou)發油(you)(you)(you)頻繁的油(you)(you)(you)庫(ku)、煉油(you)(you)(you)廠(chang)原油(you)(you)(you)區等仍應(ying)優(you)先選用，用于儲存(cun)原油(you)(you)(you)、汽油(you)(you)(you)及其(qi)他(ta)揮(hui)發性油(you)(you)(you)品。

  浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)罐(guan)的(de)種(zhong)類很多，有(you)(you)單(dan)(dan)盤(pan)(pan)式(shi)(shi)、雙(shuang)(shuang)盤(pan)(pan)式(shi)(shi)、浮(fu)(fu)(fu)(fu)子(zi)式(shi)(shi)等。常用的(de)單(dan)(dan)盤(pan)(pan)式(shi)(shi)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)罐(guan)在(zai)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)周圍建(jian)(jian)造環(huan)形浮(fu)(fu)(fu)(fu)船(chuan)，用隔板將浮(fu)(fu)(fu)(fu)船(chuan)分隔成若干個不(bu)滲漏的(de)船(chuan)室，在(zai)環(huan)形浮(fu)(fu)(fu)(fu)船(chuan)范圍內的(de)面積以單(dan)(dan)層(ceng)金(jin)(jin)(jin)屬板覆(fu)蓋(gai)(gai)。而雙(shuang)(shuang)盤(pan)(pan)式(shi)(shi)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)罐(guan)的(de)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)則是上(shang)、下(xia)兩面分別以金(jin)(jin)(jin)屬板覆(fu)蓋(gai)(gai)。不(bu)論是單(dan)(dan)盤(pan)(pan)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)罐(guan)還(huan)是雙(shuang)(shuang)盤(pan)(pan)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)罐(guan)，浮(fu)(fu)(fu)(fu)盤(pan)(pan)上(shang)面都安裝有(you)(you)梯子(zi)、平臺和(he)欄桿(gan)。建(jian)(jian)造浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)的(de)金(jin)(jin)(jin)屬材(cai)料有(you)(you)碳鋼和(he)鋁合(he)金(jin)(jin)(jin)兩種(zhong)，目前，碳鋼材(cai)料的(de)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)已逐漸(jian)被鋁合(he)金(jin)(jin)(jin)浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)所替代。浮(fu)(fu)(fu)(fu)頂(ding)(ding)(ding)(ding)(ding)一般在(zai)專門的(de)制造廠建(jian)(jian)造，作為成品部件供貨。