Difference Between Elliptical Heads vs Torispherical Heads: Henan Guojiang Precision Formed Heads Co., Ltd.

Elliptical Heads (2:1 Elliptical Heads)

Elliptical Heads are one of the most widely used Pressure Vessel Heads, Especially the 2:1 Elliptical Heads, Which is Widely Used in High-Pressure Vessels, Reactors, Heat Exchangers, and other Process Equipments.

A standard 2:1 elliptical head has a depth approximately equal to one-quarter of the outside diameter, where:

Major Axis = Outside Diameter (OD).

Minor Axis = 0.5 × Outside Diameter (OD).

The head consists of: An elliptical curved section & A straight flange (SF) section for butt welding to the vessel shell. 

Advantages of Elliptical Heads:

(1). Higher pressure resistance compared with shallow heads.

(2). Lower stress concentration due to its smooth elliptical transition.

(3). More uniform stress distribution.

(4). Suitable for pressure vessels requiring higher mechanical performance.

(5). Offers improved fatigue resistance when subjected to cyclic pressure loading.

Disadvantages of Elliptical Heads:

(1). Deeper forming depth

(2). Requires more forming work

(3). Slightly higher manufacturing cost compared with torispherical heads under similar specifications

(4). Larger forming equipment may be required for large diameters.

Torispherical Heads (Klöpper Heads / DIN 28011)

Torispherical Heads are also commonly called Dished Heads or Klöpper Heads according to DIN 28011.

Unlike elliptical heads, torispherical heads are not a continuous elliptical curve. They are composed of three geometric sections:

(1).Central spherical crown.

(2).Knuckle transition radius.

(3).Straight flange (SF) section for welding to the vessel shell.

The transition area between the spherical crown and knuckle creates a higher stress concentration area compared with elliptical heads.

Advantages of Torispherical Heads:

(1). Shallower depth compared with elliptical heads.

(2). Easier forming process.

(3). Lower manufacturing cost.

(4). Requires less material in many applications.

(5). Suitable for large storage tanks and low-to-medium pressure vessels.

(6). Widely used in chemical, food, pharmaceutical, and storage equipment.

Disadvantages of Torispherical Heads:

(1). Higher stress concentration at the knuckle area.

(2). Lower pressure capability compared with 2:1 elliptical heads under the same thickness.

(3). Requires careful design calculation for high-pressure applications.

Main Differences Between Elliptical Heads and Torispherical Heads

Application Example: 

For a tank requiring two heads:

(1). Elliptical Head may be selected for the pressure-retaining side where higher strength and pressure performance are required.

(2). Torispherical Head may be selected where a shallower profile, lower cost, or better appearance is preferred.

However, the final selection depends on:

(1). Design pressure

(2). Design temperature

(3). Vessel diameter

(4). Material grade

(5). Thickness requirement

(6). Applicable design code (ASME, EN, DIN, GB, etc.)

For stainless steel torispherical heads used in food, pharmaceutical, and sanitary applications, additional surface finishing such as 200 mesh polishing or higher polishing grades may be required to achieve a smooth and hygienic surface.

Henan Guojiang Precision Formed Head Co., Ltd. As One of Leading Manufacturer of Stainless Steel Dished Head, Custom Order Accepted. Welcom to Visit our Factory or Contact with Us freely.

By Email: Lynn Chen

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Sales2@GJ-FormedHead.com

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