Buckled Areas Around Tank Inlet 7

[ghamsa]

Pls. help with solutions or ideas to recover buckled areas on a tank.

We have atmospheric storage tank, 46 feet Diameter X 48 feet high. The tank consisted of 6 courses. The tank 24” inlet, located on course No. 3, was subjected to external force which resulted in buckled areas around the inlet. The bucked areas vary from 0.2” to 1.4” on one side of the inlet and 0.4” to 1.6” on the other side.

We did completely fill the tank with water hoping that the static force will externally push the buckled areas out and return the tank to its original condition. Unfortunately, tank hydrotesting helped a little.

Pls. help with ideas to recover these buckled areas. Many thanks

 

[JStephen]

Probably the simplest way is to just remove the nozzle and a section of shell around it and replace with new material. If the load is likely to occur again, you may want to look at using a thicker insert plate.

 

[ghamsa]

Thanks JStephen

What about hammering the internal side (inside the tank) of the buckled areas so that they come back to their orignal positions

or Do you think pulling out the inlet nozzel could help?

Again many thanks

 

[unclesyd]

What is the wall thickness of the tank where the buckling occurred?

If you have access to the inside there is sveral possibilities to recover.

The buckling maybe ironed out.

It might be able to be dogged or jacked out.

It might also be able to recover with flame straightened.

 

[vesselfab]

if it was my tank, the oly thing I would consider would be having the nozzle replace by cutting out the affected area and replacing with a new section of shell preformed to match curvature, pre beveled and with the nozzle pre-welded in to eliminate down time.

trying to move metal back into place once it is stretched can be very tricky and can finish ruining the integrity of the metal

 

[ghamsa]

The thickness is 6mm.

If I apply forces to move the metal back into place, is there a way or test to make sure that the metal integrity is not runied?

again thanks all!

 

[rhg]

ghamsa

1-determine the amount of external force
2-make proper design calculation of shell thickness
3-replace nozzle 24" with new one with thickness according to design calculation

rhg

 

[gr2vessels]

ghamsa,
The storage tank is / should be a major asset for you and your company and is not a tin of diced tomatoes, to push out the warped side with your thumb.. The buckled area has gone beyond the yield of the steel and is probably now work hardened. There is very little chance of "hammering it out" and increased likelyhood of loosing completely the strength of the plate. Even if you would somehow force the plate to yield in the opposite direction, the surface cracks will render your tank useless.
As above, don't waste time; -replace the nozzle and the plate around it with 10 mm plate or thicker if the inlet piping will continue to impinge on the nozzle.
gr2vessels

 

[ghamsa]

Thank you all for your kind attention and contributions to my thread.

I agree to replace the nozzle and plate around it with a new one based on proper design calculations.

Again Thanks

 

[JoeTank]

gr2vessels
A star for clear headed thinking. I've never been a fan of heating and beating on tanks or vessels. The tomato can analogy is excellent.

Joe Tank

 

[unclesyd]

I'm somewhat surprised that some of the remedies proposed only correct the end results of the real problem. A nozzle on a tank, especially with thin skin should never be used as an anchor point for a piping system.

The affected area as posted is very small and should be able to be address without a tank modification. The material in the tank should be unaffected by tugging, hammering or heating as anyone that has been around tank construction could attest to. Every tanker I know has an 8# maul and plenty of dogs, clips, bull pins, chainfalls along with a torch or two.