Hemispherical Head

A hemispherical head is a half-spherical pressure vessel end closure,with uniform curvature across the entire surface.It is the most structurally superior head type among all vessel heads,featuring ideal mechanical performance under internal pressure.

Structure

It is composed of a complete half-spherical curved surface and a short straight flange for welding connection with the cylinder shell.The radius of the sphere is basically equal to the inner radius of the pressure vessel body.

Performance&Advantages

Optimal stress distribution

Stress is evenly distributed over the whole curved surface with almost no stress concentration,which is far better than ellipsoidal heads and dished heads.

Maximum pressure bearing capacity

Under the same design pressure and diameter,it requires the thinnest wall thickness,which saves a large amount of raw materials.

Excellent fatigue resistance

Perfectly adapts to frequent pressure fluctuations,high temperature and high pressure working conditions.

Large internal volume

Reasonable internal space utilization for container storage.

Disadvantages

Complex stamping and forming process,high manufacturing difficulty.

Higher production cost compared with ellipsoidal head and dished head.

Larger overall height,occupying more installation space.

Common Materials

Carbon steel:Q245R,Q345R,SA516 Gr70,P265GH

Stainless steel:304,316L,321,310S,904L

Alloy steel,titanium,Hastelloy,nickel alloy

Manufacturing Process

Hot pressing,cold pressing,integral forging,spinning forming.

Followed by stress relief heat treatment,dimensional inspection,non-destructive testing(RT,UT,MT,PT).

Applicable Standards

ASME Section VIII,EN 13445,DIN 28013,GB/T 25198

Applications

High-pressure vessels,high-temperature reactors,large-scale gas storage tanks,cryogenic pressure vessels,petrochemical high-pressure equipment,nuclear power pressure vessels,large heat exchangers.