12F Roof Hinge Reinforcement for Explosion 1

[sundale]

In a 12F production tank, has anybody seen a detail where there is a single additional horizontal 18" long fillet weld to the roof/shell joint located over a vertical shell joint? The stated purpose of this detail is to provide a reinforced hinge such that the roof comes off in an explosion, but hinges over at this spot (or the roof is perhaps flung a lesser distance...) My calculations indicate the joint strength is governed by the 3/16 base metal thickness in the shell; more weld material will not provide any more strength. Thanks in advance for any responses.

 

[JStephen]

Sounds like wishful thinking to me.

 

[Duwe6]

Been there, calc'd that. API-12F tanks are so small that they can't have Frangible Roof Joints. Not enough sq-ft of roof area versus the the strength of a minimum-sized roof-to-shell weld. Also, not anchored, so with a minimal product 'heel' remaining in the tank, the floor will bulge before the roof. 12F's [w/o anchors] fail at the floor-to-shell when they are fairly empty.

To protect for Fire Case, put an emergency vent 'plug' in the roof manway/light hatch. Protectoseal makes a nice one.

 

[stookeyfpe]

The attached video illustrates Duwe6's analysis:

http://daviddrummond.com/blog/2009/05/16/lamesa-tx-tank-battery-fire-in-slow-motion/

 

[sundale]

Thank you everybody for the responses.