Frangible Roof Requirements

A frangible roof joint for small diameter tanks wherein the joint forms a flexible gastight connection between the tank shell and the roof and comprises annular link means containing an annular plate having an inner edge corresponding to a first edge thereof and an outer edge corresponding to a second edge thereof sealingly secured at or adjacent the first edge to a rim.

Frangible roof requirements.

Frangible is a word that means easily broken. In fact the frangible roof design fulfills the venting requirements due to deflagrations inside tanks for most tank sizes greater than about 35 feet in diameter. That is of course if the tanks are built according to the rules for frangible roofs. 4 2 3 2 areas that are pitted.

Api 650 gives rules for the design of frangible roof joints in fluid storage tanks. What is claimed is. Holes through roof plates shall be repaired or replaced. 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.

However experience shows that the frangible joint may not always perform as intended. See figures 7 and 8. This paper presents the results of an investigation into the frangible joint behavior of tanks designed to api 650 rules. 4 2 3 floating roofs 4 2 3 1 areas of roof plates and pontoons exhibiting cracks or punctures shall be repaired or the affected sections replaced.

Evaluate the strength of the roof joint versus the shell to floor joint. A frangible roof joint forming a flexible gastight connection between a tank shell and a roof comprising an annular link mechanism sealingly secured at or adjacent a first edge thereof to a rim of the tank and sealingly secured at or adjacent a second edge thereof to the periphery of the roof. This failure is intended to vent the tank and contain any remaining fluid. The concept of frangible roof only applies to flat bottom cone roof tanks with limited roof apex angle.

Frangible roof joints by zhi lu b s tianjin university 1982 m s tianjin university 1984 a dissertation submitted in partial fulfillment of the requirements for the degree doctor of philosophy department of mechanical engineering college of engineering kansas state university manhattan kansas 66506 1994 approved by. Api 650 paragraph 5 10 2 6 c was revised to discourage the use of frangible roof design on small diameter tanks. Other means of providing emergency venting are recommended for small tanks. The securement of the annular link mechanism to the rim and the roof is such as to permit.

Frangible roof design for tanks under 50 does not work without tank specific design. The reasoning behind present api design formulas is reviewed.