After a vessel is insulated it is neccessary to measure the amount of insulation and cladding material applied for payment purposes. There are industry agreed methods of calculating the areas applied. These are shown in the sketch and formulae below

Cylindrical Shells

The area of a cylindrical section is calculated by multiplying the height by the cicumference. The cylindrical sections in the sketch above have areas calculated below. The reason circumference is used rather than diameter is that it is easier and more accurate to measure circumference.

A1 = H1 · C1

A3 = H3 · C3

A5 = H5 · C5

Cone Sections

The area of a cone section is half of the product of the slant height and the base circumference. In the case of a frustum of a cone the area is given by