U stamp limitations

[lschmid75]

We have a U stamp and we were given a project with a 6000 gallon horizontal demin water tank that is to have a design pressure of 300 psig and it will have a 275 KW heater installed to raise the temperature to below saturation temperature. The hot water will be continuously pumped out at a low rate of flow and fresh water will be allowed in to maintain level. I was concerned that the tank may be considered a boiler requiring a stamp other than the U stamp. In searching through Section VIII I do not see what the limitations are for a U stamp. Does 275 KW require something other than a U stamp?

 

[metengr]

This sounds like a hot water heater, that would fall under ASME Section IV.

 

[powerboiler]

The design pressure 300 psi puts this vessel out of ASME Code, Section IV, heating boilers.

What you have is an ASME Code, Section I, electric boiler falling under PEB-3. You will need a "S" stamp holder to certify this vessel. You will have to have a Master Data Report P-2A for the electric boiler with the words "Boiler pressure vessel constructed to Section VIII, Division I as permitted by Part PEB". The vessel will be stamped "U" and the letters "UB" and documented on the U-1 or U-1A Data Report.

 

[lschmid75]

Metengr & Powerboiler
Thank you for your input. We have had other tanks that have electric heaters in them but were at lower pressure. these tanks had been U stamped. Can you tell me what is the limitation for falling under section IV. Is it the Nameplate pressure, the heat input, the volume?

 

[powerboiler]

Ischmid75

The scope of ASME Code Section IV, Heating Boilers is:
Up to and including 15 psi (MAWP) steam and 160 psi (MAWP) and/or 250 degrees Fahrenheit for water. If the vessel exceeds any of these parameters then you must go to ASME Code, Section I, if the vessel meets the definition of a boiler.

"Boiler" means a closed pressure vessel in which a fluid is heated for use external to itself by the direct application of heat resulting from the combustion of fuel, solid, liquid, or gaseous, or by the use of electricity or nuclear energy.