管帽標準的厚度定義不甚合理，主要體現在容器和封頭成形后的厚度要求上，對凸形封頭和熱卷筒的成形厚度要求不得小于名義厚度減鋼板負偏差(δn-C1)，由此可能導致設計和制造兩次在設計厚度的基礎上增加厚度以保證成形厚度。這種厚度的定義和標注是目前國際壓力容器界的流行方法，有其合理性，但在我國現行標準中有以下兩個問題需解通常來說管帽尺寸比較小，封頭尺寸比較大一點。
　　管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)一般(ban)(ban)用于(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)的(de)(de)端部，封頭(tou)用于(yu)容器(qi)設(she)備的(de)(de)上下(立式設(she)備)部位(wei)或左右端部(臥式設(she)備)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)一般(ban)(ban)都是外徑(jing)尺寸,象219,273,325之類的(de)(de)。管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)也稱為堵頭(tou)、蓋(gai)頭(tou)、管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)蓋(gai)、悶頭(tou),裝在管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)端外螺紋上以蓋(gai)堵管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件。用來封閉管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)路，作用與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)堵相同，但管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)可直接(jie)旋在管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)上，不(bu)(bu)須要其(qi)他管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件。一般(ban)(ban)用于(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)未端取樣(yang)口處(chu)，取樣(yang)完(wan)成后(hou)，要擰上管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)，其(qi)二是在特殊情(qing)(qing)況(kuang)下，擰掉管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)后(hou)，可以絲口接(jie)上管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)，臨時連續取料或抽料。用管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)一般(ban)(ban)在壓力(li)較低的(de)(de)情(qing)(qing)況(kuang)下，便(bian)于(yu)拆卸(xie)檢(jian)修，高中壓情(qing)(qing)況(kuang)下一般(ban)(ban)不(bu)(bu)用管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)。管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)包括凸形(xing)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)、錐殼、變徑(jing)段(duan)、平(ping)蓋(gai)及緊(jin)縮口的(de)(de)設(she)計(ji)。