ASME Section I - Miniature Electric Boiler

[IdanPV]

Hello Experts,

I have a questions regarding the requirements of ASME Section I Parts PMB & PEB.
I am dealing with the design of miniature power boiler with an immersion resistance element, where the heat is generate by the passage of an electric current through a resistance heating element directly immersed in water.

The inside diameter of the shell is 128.2mm, the gross volume is 0.0063m^3 and the MAWP is 520kPa. Therefore, this electric boiler do not exceed the limits of PMB-2.
As per PMB-2.2: "If a boiler meets the miniature classification, the rules in this Part shall supplement the rules for power boilers and take precedence over them when there is conflict."
As per PEB-2.2: "Electric boilers...that do not exceed the....limits of PMB-2 may be constructed using the applicable paragraphs of Part PMB in conjunction with this Part."

So, my questions are as follow:
1. As per PEB-15.2, "The minimum pressure relief valve relieving capacity for electric boilers shall be 1.6 kg/hr/kW input. The pressure setting shall be not
higher than the MAWP stamped on the completed boiler"
Does it the only requirement regarding the design which I described above? OR, Do I also have to meet the requirements of PMB-15.1 Regarding the pressure relief valve size (not less than NPS 1/2)?

2. General question regarding this issue, when designing a boiler as described above, which of the two parts shall I follow where there is a conflict?

P.S
I asked my A.I regarding this issue, he doesn't help much...

 

[moltenmetal]

Just out of curiosity: is this indeed a "power boiler", or is it a process steam generator?

Liquid vapourizers are frequently designed and built in the chemical process industry without being designated ASME I- and it makes many things simpler.

 

[IdanPV]

It is a steam generator which generate steam for use in an autoclave.

I can use Section VIII Division 1 for design of the boiler pressure vessel only.
But piping & PRV shall be in acc. with Section I & B31.1.
So it doesn't help much.

 

[moltenmetal]

Yes, it looks like you're really in the realm of a miniature utility boiler, with B31.1 piping and a Section I vessel and PRV. Your unit would not be a process steam or vapour generator.