Frangible Roof Weld

This video documents the research and testing on frangible joint storage tanks performed at kansas state university and thunderhead engineering.

Frangible roof weld.

The concept of frangible roof only applies to flat bottom cone roof tanks with limited roof apex angle. This failure is intended to vent the tank and contain any remaining fluid. A small diameter tank which comprises a shell having a rim at its upper edge a roof and a frangible roof joint the roof joint including annular link means sealingly secured at or adjacent 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.

This paper presents the results of an investigation into the frangible joint behavior of tanks designed to api 650 rules. The securement of the annular link mechanism to the rim and the roof is such as to permit articulation of the annular link mechanism relative to the rim and roof to a point of failure of the joint. 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. A frangible roof is a roof to shell joint or junction that is weaker than the rest of the tank and will preferentially fail if the tank is over pressurised.

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. 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. The api 650. Api 650 gives rules for the design of frangible roof joints in fluid storage tanks.

Hi henry you can refer to 3 10 2 5 addendum march 2000 which states roof plates shall be attached to the top angle of the tank with a continuous fillet weld on the top side only you may want to review the tank design if this connection ask for frangible joint not exceeding 5mm continuous weld. The reasoning behind present api design formulas is reviewed.