Minimum forming thickness
Thread Content
The design drawings for pressure vessels specify the minimum forming thickness of the pressure-bearing components (typically the cylinder and head). If the drawings require the inner surface to be polished, the amount of thinning resulting from polishing of hot-rolled steel is approximately 0.5 mm; then how should the minimum forming thickness specified in the drawings be determined? For example, the minimum forming thickness of the head is specified using one of the following methods: (1) nominal thickness – forming reduction – thickness negative deviation, or (2) nominal thickness – forming reduction – thickness negative deviation – polishing reduction. The question is: does the polishing thinning amount fall under the category of forming thinning amount?
If polishing is performed, the amount of thinning due to polishing should be considered part of the forming thinning.
Both polishing thinning and shaping thinning fall under the category of process-related thinning. In simple terms, it refers to all the thinning that occurs to that piece of material as it goes from its initial state to the point where it is ready for shipment
The minimum forming thickness of the head must be ensured to be greater than or equal to the design thickness of that head (calculated thickness + corrosion allowance). To determine this value, an amount is calculated by taking the nominal thickness minus the thickness negative deviation, minus the forming thinning amount, minus the polishing amount. If this resulting value is greater than the design thickness, it can be used as the minimum forming thickness; if it is less than the design thickness, a thicker sheet material must be used until the calculated value exceeds the design thickness.
It may not be possible to achieve good results using standard methods, as different manufacturers have varying technologies, and the sheets purchased can differ in thickness; you can ask the end-cap manufacturer to provide this information.
This post was last edited by INJQZ on 2020-3-30 at 11:16. In all three cases, it is the minimum forming thickness. From a self-protection perspective, it should be appropriate
The minimum forming thickness of the head must be ensured to be greater than or equal to the design thickness of that head (calculated thickness + corrosion allowance)