This app calculates Sphere, Hemispherical Head or Hemi Head, Dish End Petal type layout Development required in plate or sheet metal lay-outing used for fabrication. it is also called Flat pattern development of Sphere or Hemispherical Heads. This app used for petal lay-outing of Vessels End Caps. it is used in spherical type storage tank fabrication. it is used in heads or dish ends or vessel cap fabrication of pressure vessels. It is recommended to used mean dimensions for lay-outing for hig