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Elliptical heads consist of a half-ellipsoidal surface and a cylindrical straight segment. They combine the advantages of hemispherical heads, which have good stress distribution, with those of dished heads, which have shallow depths. Due to the smooth and continuous curvature of the elliptical part's meridians, the stress distribution within the head is relatively uniform. The depth (h) of an elliptical head depends on the ratio of its major and minor axes, i.e., the ratio of the internal diameter (Di) of the head to twice its depth (Di/2h). A smaller ratio results in a deeper head with more uniform stress and thinner walls but makes manufacturing difficult; a larger ratio leads to a shallower head that is easier to manufacture but has poorer stress distribution and thicker walls. Therefore, it is generally advisable for Di/2h to be no greater than 2.6. When Di/2h equals 2, it is considered as a standard elliptical head,namely semi elliptical tank head, which is commonly used in pressure vessels.
|
Type |
Elliptical Head |
|
Manufacture Standard |
As per ASME Ⅷ-1,2023 UG79, &UG81 |
|
Inner Diameter |
1676.4mm |
|
Min Thk. A/F |
18 |
|
Cutting Method |
Plasma Cutting |
|
Forming Method |
Spinning |
|
Heat Treatment |
No Required |
|
Material Designation |
SA 516 Gr.70N |
|
Material Standard |
/ |
|
Surface Treatment |
Sand Blasting |
|
NDT Method & Acceptance Cretiria |
No Required |
Carbon steel semi elliptical tank heads are widely used in petroleum, chemical equipment, transportation, power, and nuclear industries. Learning about the 9 types of corrosion of carbon steel semi elliptical heads would be better to avoid or reduce the improper operation leading to various types of corrosion for related workers. The rest 5 types of corrosion will be mentioned as below, and you could read the others at.
1. Crevice Corrosion: Crevice corrosion occurs in the crevices and covered areas on the surface of the carbon steel head, leading to intense localized corrosion.
2. Erosion Corrosion: Erosion corrosion is accelerated due to the relative movement between the medium and the metal surface, causing the corrosion process to speed up.
3. Intergranular Corrosion: Intergranular corrosion primarily affects the grain boundaries and nearby regions of the metal or alloy, while the grains themselves corrode less.
4. Stress Corrosion Cracking (SCC): SCC is caused by the combined effect of corrosion and tensile stress within a specific metal-medium system, leading to material fracture.
5. Hydrogen Embrittlement: In electrolyte solutions, metals can suffer damage due to hydrogen penetration during corrosion, acid washing, cathodic protection, or electroplating.
Despite strict delivery time for each purchase order, we fabricate the dished ends as per forming procedure approved by client step by step as the principal of " Never Apologize for Quality".
http://www.dish-head.com/