管帽标准的厚度定义不甚合理，主要体现在容器和封头成形后的厚度要求上，对凸形封头和热卷筒的成形厚度要求不得小于名义厚度减钢板负偏差(δn-C1)，由此可能导致设计和制造两次在设计厚度的基础上增加厚度以保证成形厚度。这种厚度的定义和标注是目前国际压力容器界的流行方法，有其合理性，但在我国现行标准中有以下两个问题需解通常来说管帽尺寸比较小，封头尺寸比较大一点。
　　管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)一般(ban)用(yong)于管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)的端部，封(feng)(feng)头(tou)用(yong)于容(rong)器设备(bei)(bei)的上(shang)下(xia)(xia)(立(li)式设备(bei)(bei))部位(wei)或左右端部(卧(wo)式设备(bei)(bei))管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)一般(ban)都是(shi)外径尺寸,象219,273,325之类的。管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)也称为堵(du)头(tou)、盖头(tou)、管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)盖、闷头(tou),装在(zai)管(guan)(guan)(guan)(guan)(guan)(guan)端外螺(luo)纹上(shang)以盖堵(du)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)的管(guan)(guan)(guan)(guan)(guan)(guan)件。用(yong)来封(feng)(feng)闭管(guan)(guan)(guan)(guan)(guan)(guan)路，作用(yong)与管(guan)(guan)(guan)(guan)(guan)(guan)堵(du)相同，但管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)可直接旋在(zai)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)上(shang)，不须要其(qi)他管(guan)(guan)(guan)(guan)(guan)(guan)件。一般(ban)用(yong)于管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)未端取(qu)样口处，取(qu)样完成后，要拧上(shang)管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)，其(qi)二是(shi)在(zai)特(te)殊情(qing)况(kuang)下(xia)(xia)，拧掉(diao)管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)后，可以丝(si)口接上(shang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)，临时连(lian)续(xu)取(qu)料或抽料。用(yong)管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)一般(ban)在(zai)压力较低的情(qing)况(kuang)下(xia)(xia)，便于拆卸检修，高中压情(qing)况(kuang)下(xia)(xia)一般(ban)不用(yong)管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)。管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)包括凸形(xing)管(guan)(guan)(guan)(guan)(guan)(guan)帽(mao)(mao)、锥壳(qiao)、变径段、平盖及紧缩(suo)口的设计。