Regarding end caps
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I calculated that for a tank operating at a design pressure of 10 MPa, the wall thickness of the tank body is 90 mm. Should the head also have a thickness of 90 mm? What should I do if this isn’t specified in the standards?
The formula for calculating the thickness of the head is given in 7.1.2 on elliptical heads in GB150-98; if the actual thickness is 90 mm, it is possible to use plates with a thickness of 100 mm for fabrication. The head and the cylinder are welded together using transition zones with different thicknesses.
The exact thickness of the head must be calculated. The calculated thickness should represent the minimum thickness after the head is formed; the effective thickness is then determined by deducting a certain reduction rate from this formed thickness, and C1+C2 is added to it
If standard elliptical ones are not available, a spherical seal can be used; it just needs to have the same thickness as the housing.
For caps of this thickness, there are no standards, but manufacturing companies can certainly produce them. For such high pressure levels, it is usually difficult to find caps that meet the requirements; it is advisable to consult several manufacturing firms； The thickness of the end cap can only be determined through calculation.
For vessels designed for a pressure of 10 MPa, spherical end caps are generally used, as the calculated thickness of a spherical end cap is half that of the cylinder’s thickness; the design thickness of the end cap is obtained by adding the amount of thinning that occurs during its fabrication, and this value is then rounded to give the nominal thickness of the spherical end cap. Since it is similar to the nominal thickness of the equipment cylinder, materials of the same specification can be used in the design to simplify the weld joints and ensure welding quality
High-pressure vessels generally use spherical end caps, as the calculated thickness of a spherical end cap is half that of the cylinder wall; therefore, the nominal thickness of the spherical end cap is similar to that of the vessel’s cylinder wall.
Flat lids are more commonly used for the end caps of small-diameter high-pressure equipment; they may be thicker, but they are easier to process, and the overall cost might be lower.