Ellipsoidal Head

An ellipsoidal head(also called elliptical head)is a key end-closure component for pressure vessels,defined by a smooth,semi-ellipsoidal profile and a short cylindrical straight flange.The standard 2:1 ratio(major axis=twice the minor axis)is the industry norm,balancing structural strength,material efficiency,and manufacturability.

Structure&Geometry

Consists of a rotational ellipsoidal crown and a straight flange(short cylindrical section).

Standard 2:1 axis ratio:ideal for stress distribution and pressure resistance.

Shallower than hemispherical heads,deeper than torispherical(F&D)heads.

Core Advantages

Uniform Stress Distribution:Smooth elliptical curvature minimizes stress concentrations,superior to torispherical/flat heads.

Cost-Effective Strength:Stronger than torispherical heads(thinner wall for same pressure)and far easier/cheaper to fabricate than hemispherical heads.

Space Efficiency:Lower profile than hemispheres,ideal for height-constrained installations.

Good Fatigue Resistance:Handles pressure cycling well in mid-to-high pressure systems.

Materials

Carbon steel(SA-516,Q245R,P265GH)

Stainless steel(304,316L,321,904L)

Alloy steel,aluminum,titanium,nickel alloys(for corrosion/high-temp service)

Manufacturing

Processes:cold/hot pressing,spinning,forging

Post-forming:heat treatment,NDT(UT/RT/MT),dimensional inspection

Standards:ASME Section VIII,DIN 28011,EN 13445,GB/T 25198

Typical Applications

Boilers&steam drums

Pressure vessels in oil&gas,refining,petrochemical

Chemical reactors,heat exchangers

Storage tanks,gas receivers,process vessels

Power generation,pharmaceutical,food equipment

Selection Notes

Best for 150–1000 PSI(mid-to-high pressure)

Preferred when strength,cost,and space are balanced

Thinner than torispherical heads for equal pressure

Requires less height than hemispherical heads