Repair procedure for Sump

[SSood]

Hi

I have noticed that there was a bulging in the sump area of storage Tank, and was found to be beyond permissible limit.

The sump is 1 meter in diameter and is in the center of storage tank which is 23 meter in diameter.

1.What could be the possible reason for the bulging?
2.Being an API 653 how to give method and plan of repair for this particular case?

Regards
Sood

 

[bimr]

Have a picture? Bulging in or out?

 

[SSood]

Hi Bimr

Bulging out around the sump. Refer to the attachment.

Thanks
Sood

 

[JStephen]

I can't tell exactly what that looks like. Was it built that way? Has the sump maybe floated out of position due to water below, and can't go back into position?

 

[IFRs]

If the foundation under the bottom settled due to compaction from hydrostatic load and if the pole is welded to the fixed roof, the pole may have kept the sump up as the bottom settled around it. I usually do not detail poles welded top and bottom because of this. Please help us help you by telling us what the foundation under the bottom and sump is like, what kind of attachment you have at the top of the pole.

 

[Compositepro]

Or fill dirt under the tank compacted over time, and the fill under the sump was thinner so there was less compaction.

 

[SSood]

Hi

Foundation type is concrete foundation and asphalt layer(thk not known) is there between concrete foundaton and bottom plate.
And sand layer is there between concrete and sump walls for detecting leak.
There is no pole attached.

 

[bimr]

Hard to tell from the picture. What is the bulge depth?

Is it possible that water froze and expanded under the tank?

 

[IFRs]

The picture shows a pole welded to the sump bottom. How is the pole supported at the top of the pole? Is the product heated - could the asphalt softened allowing the bottom to settle but the sand pad stayed firm? What is the height of the bulge? Is it all around the sump?

 

[Duwe6]

First, cut the pole loose and see where the sump & floor go.
If cutting the pole gives some good movement, put a thick enough baseplate under pole to push out the bulge.
If cutting the pole fails to move the sump, cut around the outer edge of the bulge. Have some floor-plate and oiled sand on hand and repair as necessary. Tank floors are simple -- don't overthink them.
And NEVER attach a pole to the roof + floor; one or the other only.

 

[valleytank]

Did this happen during hydro? In service? What is the height difference from the general floor profile?


As the others said the pipe may be at fault but don't rule out a foundation fault. It's a good idea to free the gauge pole at the base but don't leave the pipe swinging. If it's out of the question to move it, provide it with slotted guides that will bolt everything together and allow for thermal expansion but keeping it from moving around.

It wouldn't hurt to MPI the sump flange seal weld. and inside corner.