Definition Of Head Thickness

The thickness definition of GB150 and related head standards is not very reasonable, mainly reflected in the thickness requirements of the container and head after forming. The forming thickness requirements for convex heads and hot rolls should not be less than the nominal thickness minus the negative deviation of the steel plate（ δ N-C1), which may result in design and manufacturing increasing the thickness based on the design thickness twice to ensure the forming thickness. For this reason, the concept of minimum forming thickness was once proposed: "The thickness that needs to be ensured after the hot rolled cylinder or convex head is processed and formed, and its value is not less than the design thickness. That is to say, the designer should indicate the nominal thickness and minimum forming thickness (i.e. design thickness) on the drawing δ d) This allows the manufacturing unit to decide whether to add manufacturing thinning based on the manufacturing process and the original design roundness. The definition and labeling of this thickness is a popular method in the international pressure vessel industry as of 2013, which has its rationality. However, there are two issues that need to be addressed in China's current standards.