Frangible Joint

[scherjeal]

What is frangible joint ?? API 653 Says when frangible roof to shell joint.. What does it Mean ? What is frangible joint mean ??

[gtaa]

A frangible joint is a joint that's made intentionally weak. On a storage tank this is the joint between the roof and the tank walls. In the event of an internal explosion, the roof will lift off, but the walls will remain intact and contain the liquid and fire. This prevents the tank walls lifting from the floor and spilling the contents.