Design verification of existing Pressure Vessel

[manj1987]

I have a proposal in which I will have to verify and model couple of pressure vessels on PVElite. I am not sure exact why they want to remodel them. I have raised below clarification. Kindly comment if someone has done similar task:

1- Our scope is to verify existing pressure vessel as per latest UT report(thickness) and taking design and dimensional parameters from existing As-built drawings, calculation and data sheet. Client to
confirm.
2- Verification will be done against latest ASME code and with main objective is to know if de-rating the equipment is needed or not based on vessel thickness and nozzle reinforcement. Client to confirm.
3- Any further assessment as per fitness for service standard API 579 will not be part of scope.
4- Client to confirm that along with latest ASME, vessel need to be verified for latest client specification. Client to confirm
5- Client to provide As-built drawings, calculation and data sheet for every equipment. Client to confirm.
6- UT report(thickness report) will be provided by client. Client to confirm.

 

[LittleInch]

Material reports and test data?
Construction reports / tests?

Why don't they just hydrotest it?

If you have pits or areas of corrosion are you going to assume a uniform thickness?

I thought PVElite was for designing new vessels?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[manj1987]

There is no material study/CMP . My understanding is first they just want to just rerun the ASME calculation on software to know if there will some impact due to reduced thickness. To be honest I am not 100% sure why they want to remodel. Above are just my assumption as base line.

 

[LittleInch]

That's my point though. How is reduction in wall thickness being used?

A global reduction?
Can PVE do local reductions?
Surely there will be a reduction in MAWP if some metal has disappeared

Pitting is not easy to assess unless you take a conservative view and regard the entire wall thickness as gone.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JStephen]

If the original vessels were designed with a higher factor of safety, you'll see reduced thickness when you re-run the design- but I don't know that that reduction is normally allowed in the evaluation of existing vessels.

 

[Cobra17]

if you are using UT reports for the thicknesses it is likely that they are seeing if the vessel needs to be de-rated due to corrosion. This way they don't have to look at the calculations and figure out if it is still good. I see this all the time.

But if you are not adding any new components to the pressure boundary, you should run it to the year/addenda that the vessel was built to, not the current code.