U-1 Vs Name Plate

[Corgas]

I'm in the process of rerating a PV and just found that materials listed in U-1 forms are different from materials listed in nameplate.

PV was built back in 1972.

Which one should I use?

Thanks,

 

[SnTMan]

Corgas, you maybe better use the actual MOC's

Regards,

Mike

 

[Corgas]

SnTman,

Do you mean materials listed on nameplate?

 

[TGS4]

No - he means the ACTUAL. If the U-1 and the nameplate are different, what makes you think that what they used were reflected on one or the other? Maybe both the nameplate and U-1 are wrong...

Get a PMI there and use that as your baseline. If it's a material grade issue, you're stuck getting coupons and testing. I certainly wouldn't trust either nameplate or U-1 in that situation.

 

[Corgas]

TGS4:

Problem is that it's a material grade issue and I just can't cut a hole on the PV to get coupons and testing.

Thanks,

 

[jte]

Well, I don't think that you can just throw up your hands and run away screaming. Corgas could have done that all by himself without coming here for constructive ideas.

If any engineering or fab drawings are available, see if the material is listed on them. Hopefully it'll match one of the other two sources. I'm ok with going with two out of three.

I presume that the sucess of this rerate depends on the material grade? If not, take the weaker one and run with it. How 'bout running the calc's with the weaker one and seeing if the design is sufficient for the original design conditions. If it is, chances are the vessel was fabricated of the weaker material. If it is not, then its not unreasonable to presume that the higher grade is the correct one.

Finally, you can cut a hole in the vessel on the run if you need to get coupons for testing. If the tmin on the vessel is less than 3/8", I think you just might happen to need a new 3" nozzle somewhere on the vessel! Hot tap a new nozzle in as a repair since reinforcement calc's are not necessary, and keep the coupon for testing. Its not done frequently, but more often than you might think!

jt

 

[SnTMan]

If I had to pick just one, I'd probably go with the U-1. Presumably a little more scrutiny is involved.

Regards,

Mike

 

[Corgas]

Materials listed on drawings corresponds to U-1.

Vessel is 4.75" thick!!!!!!! with corrosion allowance of 1/16".

I'll go with materials listed on U-1 forms.

Thanks everyone for your comments and advise.

Corgas.

 

[MrBTU]

Another option is to go back to the manufacturer. If they have the old records, they have at least three other points of reference - what is in the old calcs, what is on the bill of material, and what they purchased, and material test reports if you're really lucky.