Cone shell structure design

When designing the structure of the conical head, first determine the size of the half apex angle of the required conical head, and then judge whether the cone head adopts the flange design according to the size of the half apex angle. If the half apex angle α ≤ 30°, the large end and the small end of the cone head can use unfolded cone shells; if the half apex angle is 30° ≤ α ≤ 45°, the big end of the cone head should be folded For the setting of the edges, the small end may not be folded if the strength calculation is satisfied; if the half apex angle is 45°≤α≤60°, both the big end and the small end of the cone shell should be set with hemming; if the half apex angle For α>60°, flat heads should be used instead, or calculations should be made by means of stress analysis.

1 eccentric cone shell

Due to the special function requirements of some equipment, such as reboilers, pig receivers, etc., eccentric cone shells are required. Eccentric cone shell refers to a special cone shell connecting two cylinders with parallel axes but different diameters. For this type of equipment subject to internal pressure, the included angle between the eccentric cone shell and the cylinder should not exceed 30°, and at the same time It should also be noted that the difference between the axis of the two cylinders should not be more than half of the difference between the diameters of the two cylinders.

2 Calculation of tapered head

Due to the particularity of the conical head, there is a change in geometric shape where it is connected with the cylinder, and its radius of curvature changes. Therefore, a certain lateral thrust will be generated at the joint, which will cause greater edge stress and bend easily. Therefore, in the design process of the cone head, in addition to the calculation of the thickness of the cone head, the large and small ends of the cone head should also be checked to determine whether the connection part between the cone head and the cylinder body is required. strengthen.

3 Reinforced design of cone shell

When designing the connection between the cone shell and the cylinder, it should first be judged whether it needs to be strengthened. In GB150, a reinforcement diagram for determining the connection of the cone shell is given. You can check the diagram to determine whether the connection needs to be reinforced. Through the analysis of the reinforcement diagram, the main factors that affect the determination result are the half apex angle of the cone shell, the calculated pressure and the allowable stress of the material used for the cone shell at the design temperature.

In the actual design process, the strengthening method of the cone shell can be changed by changing the half apex angle of the cone shell and the selected material to meet different design requirements. It can be seen from the drawing that if the thickness of the cone shell needs to be increased to meet the strengthening effect, a reinforcement section should be added at the junction of the cone shell and the cylinder. The thickness of the reinforcement section of the cone shell should be the same as the thickness of the cylinder reinforcement section. .

Calculation of Conical Shell in SW6

Through SW6, the relevant data of the conical head can be calculated conveniently and quickly. In SW6, input the basic data of the cone shell and cylinder, including design pressure, design temperature, cylinder diameter, material selection, etc., and check the design of the cone shell part, you can directly judge whether the cone shell needs to be strengthened, and Give the thickness and length required for reinforcement. Therefore, in an actual project, it is very important to strengthen the design of the large and small ends of the cone of a reboiler cone. In general, the required length of the small end reinforcement section of the cone shell is 39.23 mm, the required length of the cylindrical reinforcement section is 36.71 mm, and its calculated thickness is 2.70 mm; the required length of the large end reinforcement section of the cone shell is 84.39 mm, the cylinder The required length of the reinforcement section is 78.96 mm, and its calculated thickness is 3.1 mm.

4 Manufacturing of cone head

Due to the special structure of the tapered head, its manufacturing method is also different from other types of heads. For tapered heads without folding edges, in general, direct rolling is adopted to complete welding and stamping. For tapered heads with folded edges, due to certain difficulties in direct rolling, generally the direct blanking is a fan-shaped steel plate, which is then rounded by a plate rolling machine, and then welded.

As an important pressure component of the container, the conical head is particularly important for its structural design and verification calculation. In the design process, the thickness of the conical shell and the design of the reinforcement section are determined through the auxiliary calculation of SW6.

- 06 Dec 2019 -

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