An excellent web based tool for Ellipsoidal Head thickness calculation under internal pressure. It also gives allowable Stress of material at a desired design temperature. This and many other tool for Pressure Vessel design as per ASME Section VIII Div. 1 would be useful for Static Equipment Engineer.

Heads are formed steel plates for pressure vessels and heat exchangers. The heads are usually found at the ends of an equipment, top or bottom for vertical vessels and left right for horizontal vessels. There are only a few shapes used for the heads that have proven to be useful. If the head is cut in half over the diameter of the head, the shapes follow more or less an ellipse.

The strength calculation of heads are one of the frequently performed calculations since most equipment consist of one or two of them. The Head Thickness page is an example page to calculate the wall thickness of heads, ellipsoidal, torispherical, kloepper and korbbogen heads. Calculation codes are ASME, Dutch Rules and the EN Euronorm.

Ellipsoidal Head thickness calculation is based on para UG-32(d) of ASME Section VIII Division 1 2011 edition code book.

Where in Ellipsoidal Head thickness is given by:

t = P * D/(2SE – 0.2P)

t = head thickness in corroded condition
P = Design pressure
D = inside diameter of head skirt
S = Maximum Allowable Stress at design temperature
E= Joint Efficiency

This tool also calculate head thickness on OD basis as per Appendix 1-4(c) of ASME Section VIII Div. 1, which is

t = P * Do*K/(2SE + 2P(K-0.1))
Do = outside diameter of Head
K = a factor for ellipsoidal Head calculation.

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