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.

Even when using a frangible roof however some owners still. Such relatively weak roof to shell joints are known as frangible. Frangible roof tanks are also vulnerable to damage if overfilled. This paper presents the results of an investigation into the frangible joint behavior of tanks designed to api 650 rules.

4 8mm thick plate a. 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. Api 650 gives rules for the design of frangible roof joints in fluid storage tanks.

By way of example for a tank having a diameter of 20 feet 6 lm a shell of 3 16 in. For reasons discussed above many tank owners prefer to satisfy emergency venting requirements with a frangible roof particularly for tanks without a floating roof because of the frangible roof s potential to vent deflagrations without substantial damage to the shell or bottom. Frangible roof tanks are also vulnerable to damage if overfilled. By way of example for a tank having a diameter of 20 feet 6 lm a shell of 3 16 in.

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. Frangible is a word that means easily broken. The concept of frangible roof only applies to flat bottom cone roof tanks with limited roof apex angle.

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. Describes research that evaluates the ability of the present api 650 tank design criteria to ensure the desired frangible joint behavior. The reasoning behind present api design formulas is reviewed.