The national standard elliptical pipe cap is a standard elliptical pipe cap, so it is selected δ N=8mm. According to the technical information of the specialized pipe cap manufacturing plant Di= δ The thinning amount of the n=8 pipe cap during processing is C3=1.5mm, and the thickness is excellent with a rounding value of △ 2=0.5. If the forming thickness of the pipe cap is required to not be less than the nominal thickness δ If the negative deviation C1 of the steel plate is reduced by n, then the feeding thickness is: δ S= δ N+C1+C3+△ 2=8+0+1.5+0.5=10mm, while the small thickness after forming is 8.5mm. If the forming thickness of the pipe cap is not less than the design thickness δ D (should be taken as δ E value), then the feeding thickness is: δ S= δ D（ δ e) +C3+△ 2=8mm, and the formed small thickness is 6.5mm, which is greater than the effective thickness δ e. Larger than the design thickness δ D and calculate thickness δ。 From the above, it can be seen that two different requirements result in a 2mm difference in the feeding thickness of the pipe cap, while the weight difference is as much as 300kg. The inner diameter of Hebei carbon steel pipe cap container is Di=4000mm, the calculated pressure is Pc=0.4MPa, the design temperature is t=50 ℃, the pipe cap is a standard elliptical pipe cap, the material is 16MnR (the allowable stress of the material is 170MPa only at the design temperature), the negative deviation of the steel is not more than 0.25mm and does not exceed 6% of the nominal thickness, the corrosion allowance is C2=1mm, and the welding joint coefficient of the pipe cap splicing welding= 1

Calculate the calculated thickness, design thickness, and nominal thickness of an elliptical pipe cap using a standard pipe cap. Hebei Carbon Steel Pipe Cap KpDi Cap Manufacturer Calculated Thickness δ=----------------= 4.73mm2[ σ] T Φ- 0.5pc Hebei Carbon Steel Pipe Hat Zehao Pipe Fitting Co., Ltd. Calculated Thickness δ D= δ+ C2=4.73+1=5.73mm pipe cap manufacturer considers standard elliptical pipe caps with excellent thickness effect δ E should not be less than 0.15% of the inner diameter Di of the pipe cap, with a thickness of excellent effect δ E=0.15% Di=6mm δ E& Gt; δ d. C1=C2=nominal thickness δ N= δ E+C1+C2=6+0+1=7mm. Considering the standard specification thickness of the steel, a thickness increase of 1mm was made, and the sales volume was good. The design roundness value △ 1=1 is therefore taken as δ N=8mm. According to the technical information of the specialized pipe cap manufacturing plant Di= δ The thinning amount of the n=8 pipe cap during processing is C3=1.5mm, and the thickness is excellent with a rounding value of △ 2=0.5

If the manufacturer of the pipe cap requires that the forming thickness of the pipe cap should not be less than the nominal thickness δ If the negative deviation C1 of the steel plate is reduced by n, the feeding thickness will be increased δ S= δ N+C1+C3+△ 2=8+0+1.5+0.5=10mm, while the small thickness after forming is 8.5mm. If the forming thickness of the pipe cap is not less than the design thickness δ D (should be taken as δ E value), then the feeding thickness is: δ S= δ D（ δ e) +C3+△ 2=8mm, and the formed small thickness is 6.5mm, which is greater than the effective thickness δ e. Larger than the design thickness δ D and calculate thickness δ。 As can be seen from the above, the manufacturer of the pipe cap has two different requirements, resulting in a 2mm difference in the feeding thickness of the pipe cap and a weight difference of up to 300kg. The thickness definition of pipe cap manufacturers GB150 and related pipe cap standards is not very reasonable, mainly reflected in the thickness requirements of containers and pipe caps after forming. The forming thickness requirements for convex pipe caps and hot rolls should not be less than the nominal thickness minus the negative deviation of the steel plate（ δ N-C1)