Elliptical Head

The elliptical head is the most commonly used end closure component for pressure vessels. It generally consists of an elliptical curved surface integrated with a straight flange. It is mainly applied to seal vessel openings, withstand internal medium pressure, and maintain the structural and pressure integrity of pressure vessels.

Compared with other vessel head types, elliptical heads feature superior mechanical performance. Their maximum stress is positively correlated with the ratio of the major axis to the minor axis. When the ratio reaches 2:1, the maximum stress is nearly equivalent to the circumferential stress of the cylinder, enabling uniform and smooth stress distribution. This creates an optimal balance between pressure resistance and manufacturing feasibility. In addition, the straight flange effectively avoids stress concentration at the welding joint between the head and cylinder, reduces structural cracking risks, and strengthens the overall load-bearing capacity of the connecting section.

With a compact structure, reasonable stress distribution and excellent formability, elliptical heads are widely applied in pressure-bearing storage tanks, reaction vessels and heat exchange equipment across petrochemical, energy and power, biopharmaceutical, and food processing industries. We provide elliptical heads in various thicknesses and material specifications, which can be customized according to actual pressure requirements, fluid characteristics and vessel dimensions to match diverse operating conditions.

In accordance with the GB/T 25198 standard, elliptical heads are divided into two main types: EHA and EHB. EHA heads adopt standard elliptical curves for more uniform stress distribution, while EHB heads feature optimized curvature radii to achieve higher pressure resistance at the same wall thickness.

Straight edge height is a key dimensional parameter. As specified in GB/T 25198-2010, the straight edge height is 25 mm for elliptical heads with a nominal diameter (D) ≤ 2000 mm, and 40 mm for those with a nominal diameter (D) > 2000 mm.

Thickness specifications cover four core dimensions: calculated thickness, design thickness, nominal thickness, and minimum forming thickness. Taking the DN4000 specification as an example: the calculated thickness is 4.73 mm (theoretical minimum) plus a 1 mm corrosion allowance, bringing the design thickness to 5.73 mm. After deducting the negative tolerance of steel plates, the nominal thickness is rounded up to 7 mm or 8 mm, with the minimum forming thickness guaranteed to be no less than 6 mm.