Frangible Roof Tanks

The concept of frangible roof only applies to flat bottom cone roof tanks with limited roof apex angle.

Frangible roof tanks.

Thus appropriate measures wellknown to tank designers are required to insure that the liquid level in the tank does not rise above the top straight side of the tank. Frangible roof tanks are also vulnerable to damage if overfilled. Such relatively weak roof to shell joints are known as frangible. Eemua 180 gives guidance to designers and users of such tanks on the practical steps that can be taken in design operation and maintenance to predispose the roof to shell joint to fail in preference to the shell to bottom joint thereby ensuring retention of the tank s contents.

Describes research that evaluates the ability of the present api 650 tank design criteria to ensure the desired frangible joint behavior. Thus appropriate measures wellknown to tank designers are required to insure that the liquid level in the tank does not rise above the top straight side of the tank. Frangible roof tanks are also vulnerable to damage if overfilled. The reasoning behind present api design formulas is reviewed.

In the event of over pressurization the frangible roof to shell joint is designed to fail before the tank shell or the shell to bottom joint. By way of example for a tank having a diameter of 20 feet 6 lm a shell of 3 16 in. Frangible is a word that means easily broken. Even when using a frangible roof however some owners still.

This paper presents the results of an investigation into the frangible joint behavior of tanks designed to api 650 rules. Api 650 gives rules for the design of frangible roof joints in fluid storage tanks. 4 8mm thick plate a. In such tanks the roof to shell joint is intended to fail in the event of overpressurization venting the tank and containing any remaining fluid.

4 8mm thick plate a. This failure is intended to vent the tank and contain any remaining fluid. 1 evaluation of the area inequality as a method to predict the buckling response of the compression ring 2 effect of roof slope tank diameter and weld size on the frangible joint and 3 effect of the relative strength.