Name Plate Stamping & Design Conditions

[SnTMan]

Hello All. I am designing a small tank to be used as a test vessel for a heat exchanger bundle. The bundle external design pressure is 500 PSI, hydro at 750. The company will retain this vessel and it could be used on any future orders for this product.

I feel fairly well justified in using 500 psi as the vessel design pressure, however I want to apply a name plate and stamp it with design data for future use and tracibility. I do not plan to Code stamp at this time.

I do recognize that at 750, stresses will be above Code allowables, as in most any vessel at hydro, and as such 750 would not usually be considered as the "MAWP".

Question is: Should MAWP be stamped 750 even though design is 500? I feel that having 750 stamped on the name plate is better than stamping 500 and depending on "the future" to recognize that the vessel can be used for a 750 hydro.

Any other thoughts or advice?

Regards,

Mike

 

[dtn6770]

Since your not going the Code Stamp route why not just go with "DO NOT EXCEED 750 PSIG" or "750 PSIG MAX." and avoid the entire design/mawp issue.

 

[JoeTank]

I recommend that the MAWP of the test vessel be specified as 750 psi. That is the workng pressure of the test vesssel.

Joe Tank

 

[JStephen]

It seems to me that if you stamp it with the 750, then some future person could reasonably assume that it is good for a hydrotest at 1.3x750 or 1.5x750- so I would say, stamp it with 500 or 750/1.3 or whatever it's actually designed for.

 

[SnTMan]

JStephen, I definitely don't want something like that happening. I didn't mention I planned on using a standard name plate that has "MAWP" and so forth engraved or etched on it and limited space for "notes". Maybe I just need to go with a blank plate and stamp everything on it, that will give me more flexibility to say what needs said.

Thanks, all.

Mike

 

[JoeTank]

If you operate a vessel at ASME hydrotest pressures the shell stresses are going to be as high as 90% of yield. That's way too high to consider for normal operation. If you are going to test assemblies at 750psi, the vessel should be designed with an MAWP of 750. This pressure should not be exceeded during any test in the future.

Joe Tank

 

[MJCronin]

Mike,

Where will this tank be installed ? What is the volume

I do not believe that it is up to the owner or designer to determine if a pressure vessel installed in the USA needs be an ASME Code stamped pressure vessel......

It is a matter of state law.

If the vessel is very small it may be exempt from ASME code requirements


-MJC

 

[SnTMan]

MJCronin, tank is only for shop use, it will not be in any commercial operation. It is only for external hydrotesting of small bundles. However it is not small enough to be exempted from the Code on a volume basis. The AI at this facility is of the opinion it does not need stamped, however it will be built and used in one of our other plants in a different jurisdication, and the AI there will have the final say as to whether it is stamped, I'm sure.

JoeTank, stresses at hydro are moderately above Code allowables, but nowhere near 90% yield. It will not be used frequently.

I ended up just stamping information on a blank plate, including "Do Not Exceed 750 psi"

Thanks again for the input.

Mike

 

[AravindSujay]

Hi Mike,

What does "Do not exceed 750 psi" means? - Operating / Hydro?

In future, one can even operate the tank at 750 psi which is a Hydro Press and is not supposed to.

you should have mentioned clearly "DO NOT EXCEED HYDRO PRESS OF 750 PSI"

Thanks,
Aravind Sujay

 

[SnTMan]

AravindSujay, It just means Do Not Exceed 750 PSI. Ever.

Regards,

Mike