Torispherical Dishes have Crown Radius & Knuckle Radius .

Ellipsoidal Dishes do not have constant radius as it follows a elliptical curve . Code permits a Torispherical Dish with Crown Radius as 0.90 ID & Knuckle Radius as 0.17 ID to be treated as 2:1 Ellipsoidal Dish . This is how Ellipsoidal Dishes are usually made . Otherwise to make a Ellipsoidal dish , single punch/die set is needed.

Inside height for 2:1 Ellipsoidal Dish is 0.25 ID . Torispherical Dish height is lower than this .

Torispherical dish ends are mostly preferred for low pressure operations.

While ellipsoidal dish ends are recommended for higher pressure as it can sustain a high pressure easily because it is having a more area which in turns gives the less thickness.

For example, if you took one ellipsoidal head & one torispherical head of same diameter, then the thickness of the ellipse will be less than the thickness of the torishperical dish end.

Basically, if you are increasing the radius of curvature, surface area will increase & vice versa. Which means hemispherical heads will give lesser thickness than ellipsoidal heads because of increased curvature.

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Makrand Pandurang Sakpal,
Static Equipment Design,
makrands9@gmail.com,
Ph no:- 9967949656.