Elliptical head EHA

Elliptical head is also known as oval head. An elliptical head is a head composed of a rotating ellipsoidal surface and a cylindrical straight section.

## Functions of Elliptical Heads

1. When a pipeline terminates and no further extension is intended, the head is welded to the pipe to serve as an end closure.

2. Used on pressure vessels, with one head at the top and one at the bottom, and a straight pipe section in the middle to form the vessel body.

An elliptical head with a ratio of major axis to minor axis of 2.0 for the generatrix of the rotating ellipsoidal surface is customarily referred to as a standard elliptical head. The mechanical properties of elliptical heads are second only to hemispherical heads but superior to dished heads. Since the depth of an elliptical head falls between that of hemispherical and dished heads, the requirements for stamping equipment and dies, as well as manufacturing difficulty, also lie between the two — easier than hemispherical heads but more difficult than dished heads. In recent years, the adoption of the spinning manufacturing process has facilitated the production of large-diameter elliptical heads. Due to their favorable overall performance, elliptical heads are widely used in medium and low-pressure vessels.

## Application Scope of Elliptical Heads

Elliptical heads are extensively applied in industries including petroleum, electronics, chemical engineering, pharmaceuticals, light textiles, food, machinery, construction, nuclear power, aerospace, and national defense.

## National Standards for Elliptical Heads

1. The lobes of elliptical heads (including integrally supplied heads with lobes), lobes of spherical heads, and lobes of flanged transition sections (including integrally supplied conical sections with lobes) shall be inspected using full-size three-dimensional templates. The corner radius of the transition zone shall not be less than the specified value on the drawing, and the maximum clearance for shape deviation shall be ≤3mm. The flange radius of the transition section shall not be less than the drawing-specified radius.

2. When the chord length of lobes for elliptical heads or spherical heads is ≥2000mm, the chord length of the flat template shall be no less than 2000mm; when the chord length of the lobes is <2000mm, the chord length of the flat template shall be no less than the lobe chord length.

3. Integral elliptical heads and segmented elliptical heads shall comply with JB/T 4746-2002; spun heads shall comply with JB/T 4746-2002; transition sections shall comply with JB/T 4746-2002; spherical heads shall comply with GB 12337-1998 Steel Spherical Storage Tanks, and shall also meet the relevant provisions of GB 150-1998 Steel Pressure Vessels and HG 20584-1998 Technical Requirements for Fabrication of Steel Chemical Vessels.