Frangible Roof Tanks

By way of example for a tank having a diameter of 20 feet 6 lm a shell of 3 16 in.

Frangible roof tanks.

4 8mm thick plate a. 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. Api 650 gives rules for the design of frangible roof joints in fluid storage tanks. Such relatively weak roof to shell joints are known as frangible.

This paper presents the results of an investigation into the frangible joint behavior of tanks designed to api 650 rules. The reasoning behind present api design formulas is reviewed. 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. Frangible roof tanks are also vulnerable to damage if overfilled.

Even when using a frangible roof however some owners still. The concept of frangible roof only applies to flat bottom cone roof tanks with limited roof apex angle. However in the context of tanks the word has a specific meaning and is defined in the main tank construction standards bsen 14015 and api650. By way of example for a tank having a diameter of 20 feet 6 lm a shell of 3 16 in.

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. 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. 4 8mm thick plate a. 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.

Frangible roof tanks are also vulnerable to damage if overfilled. This failure is intended to vent the tank and contain any remaining fluid. Frangible is a word that means easily broken.