shell out of roundness repair 1

[abangbikerz]

we have a client asking us to repair their pressure vessel that had been become oval in shape due to years of service. we had no idea how to do it since we never do it before. however one idea comes to mind which is removed all the shell plate weldment and rerolled the plate to flatten it back and rolled is back to its proper radius. does anyone have anything like this before. is it possible?

 

[DriveMeNuts]

Photos?
Sounds weird.

 

[MJCronin]

Now, ..... You are sure that it didn't fall off of a truck and that no fork-lift truck accidently backed into it ..... Right ?

The Pressure Vessel decided to change shape all by itself as it got older, Right ? ...... (much like me in 2020)

MJCronin
Sr. Process Engineer

 

[mk3223]

Does it make sense to replace this vessel, in terms of schedule, cost, etc., instead of repairing it as described?
And, may find out why the shape of the vessel is changed, or if any design change may be needed to prevent it from happening again.

 

[blacksmith37]

Delayed coker vessels deform because of temperature variations and temperature changes during service. They operate at low pressure and low ( general) stress so distortion is not a problem. In other process vessels I have seen a few local bulges from severe local overheat; then the only concern was had temperatures affected strength, not geometry. So, I wonder what the objective reason is to adjust the shape , but that is no answer.

 

[abangbikerz]

it is an autoclave with loaded cages moving in and out of the equipment+pressure & hot temperature that cause the shell plate to be oval. The owner of the vessel are quite thrifty and he prefer to explore the repair option than replacing it with new one. Cost wise if we manage to repair it quickly it is much cheaper than replacing it with new one as material cost nowadays is very high. The problem is we have no idea if anyone have done anything like this before and what are the problem and limitation

 

[TGS4]

Before going down the repair route, is a repair needed at all. Does the vessel pass a fitness for service assessment per API 579-1 / ASME FFS-1?

 

[saplanti]

This is essential for the vacuum service. But you may be able to add reinforcing rings externally to overcome the problem if acceptable for corrosion and thermal loads.
In case the autoclave does work under internal pressure you may not need to do anything unless it has severally damaged.
Perhaps some photos can be useful to see the damage in detail, and make adequate recommendation.
I hope you follow the requirements of ASME FFS for your need.

 

[r6155]

@ abangbikerz
The problem may be that it is not free to expand and contract during thermal conditions.
Did you check it?

More information: shell diameter, thickness, material, design temperature/pressure, Dmax minus Dmin, drawing, ....etc

Regards

 

[jtseng123]

Roll it round, and VT/MT/PT check surfaces and welds to ensure no cracks no porosity. If any, just repair. Then hydrotest one more time. If it passes, good to go.