Does it fall under ASME BPVC? 1

[IdanPV]

Hi All,

A tube with outside diameter of 3/16" and 1mm wall thickness is winding around a 1000Watts heating element.
The fluid (water) enter to the tube in one side and exit after vaporization, as steam, from the other side.
Tube length is 200mm. No welding or brazing is involved in the construction.

Does this configuration need to be design, constructed and stamped in accordance with ASME BPVC (Section I or VIII)?

I have go through Section VIII-1 and the only thing I found is that according to Section VIII-1, U-1(c)(2), structures whos primary function is the transport of fluids are not included in the scope of the division.

I didn't find anything in Section I.

Please advise.

 

[Dhurjati Sen]

Check ASME B 31.1

DHURJATI SEN
Kolkata, India

 

[IdanPV]

Dhurjati Sen,
Thank you for your comment.

I don't think that B31.1 is applicable.
I am not dealing with design of Power Boiler, and the component which I described above is not part of BEP.

Maybe you can be more specific?

I try to understand if the winding tube is falling under ASME BPVC (I or VIII) and need to be design, constructed and stamped in accordance with one of the two.

 

[SnTMan]

IdanPV, as to Sec VIII, Div 1, read carefully U-1(c)(2). Your answer is within.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[IdanPV]

SnTMan,
I have read it few times, may be I missed something.
U-1(c)(2) "...however, any pressure vessel which meets all the applicable requirements of this Division may be stamped with the Certification Mark..."
I am looking for "shall", not "may be".

U-1(c)(2)(-a) "those within the scope of other Sections;" Does the configuration which described above is within the scope of other Sections? may be Section I?
U-1(c)(2)(-b) "fired process tubular heaters" I think the configuration above is kind of "fired process tubular heaters" , but I'm not sure.
U-1(c)(2)(-c) N/A.
U-1(c)(2)(-d) "structures whose primary function is the transport of fluids from one location to another..." the configuration is part of piping system.
U-1(c)(2)(-e) Same as above.
U-1(c)(2)(-f) N/A.
U-1(c)(2)(-g) N/A.
U-1(c)(2)(-h) N/A.
U-1(c)(2)(-i) Not a vessel.
U-1(c)(2)(-h) Not for human occupancy.

So, I am a bit confused now.
I don't think this configuration is within the scope of VIII-1, but I'm not sure.
And, I'm really not sure if it's within the scope of Section I.
As I wrote at the beginning, I am looking for some mandatory requirement regarding this configuration.

 

[SnTMan]

IdanPV, UG-1(c) gives a number of bases to exempt a pressure vessel (a piece of equipment containing pressure) from meeting Sec VIII, Div 1, but does not force one to do so. Per UG-1(c)(2).

Re U-1(c)(2)(-b): What makes you think a resistance heater makes it fired?

Re U-1(c)(2)(-i): If you don't classify it as a vessel why are you concerned about a pressure vessel code?

I am not familiar with Sec 1, but I seriously doubt your vessel, if you want to call it that, is required to meet that Code.

You've got a tiny piece of tubing heated with same power as a drip coffeemaker or a halogen work light. Don't over complicate it.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[IdanPV]

SnTMan,
Thank you for the detailed response.

I am looking for a statement which will help me to exempt the configuration from the Code requirements.
U-1(c)(2)(-b): Interpretation Number I-81-01 dealing with this issue. This interpretation explain whether or not a boiler is Fired or Unfired.
As per the above Interpretation: "An electric boiler where heat is applied to the boiler pressure vessel externally by electric heating element, induction coils, or other electrical means is consider to be a fired steam boiler."

I know it's not a pressure vessel nor boiler, it's just a "tiny piece of tubing heated with same power as a drip coffeemaker". But it's generate steam at pressure which is higher than the atmospheric pressure and I just want to make sure I am not making any mistakes.

Can I state that since there are no welding/brazing involved this tube can be exempt from the Code?

By the way,
as far as I know, Section I has no limitation regarding size or power. Even if the power is very small the boiler shall meet the Code requirements.

 

[moltenmetal]

This sounds like a process steam generator, NOT a boiler.

The tube would be regulated under a pressure PIPING code like B31.3, not section I. Wouldn't matter if the heating element were a heating element or a piece of heat trace attached to the tube along its length, it's still a process steam generator.

It will also make bad quality steam, the way you've described it, unless the water flowrate is VERY low indeed. Unless the flow is very low indeed, it will emit water droplets even when the mixed stream temperature is 100 degrees superheated.

Why is that? If you've ever seen a "percolator"- a glass coffee pot which uses steam generation to propel water upward to make poor quality drip coffee, you'll understand.

As steam is generated inside the tube, it propels water rapidly through the tube- and because the tube is of such small ID, there is no room for liquid and vapour phases to coexist simultaneously so you get slug flow- slugs of water propelled by pockets of expanding steam. You will need a chamber at the discharge to allow vapour/liquid separation or better still, a heated chamber containing something like metal or ceramic shot, to vaporize the exiting water.

That's based on testing of units nearly identical to what you describe.

 

[SnTMan]

IdanPV, you have not stated the design pressure and temperature, but I'd exempt this piece of equipment from Sec VIII Div 1 under U-1(c)(2)(-i) on the basis of diameter without further thought.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[IdanPV]

moltenmetal,
Thank you, I will look in B31.3.

SnTMan,
Thank you for your comments.
The question is if I can classified this item as "Unfired" and then exempt it from VIII-1 under U-1(c)(2)(-i)

As I said, if it shall be classified as "Fired" so maybe I'll have to use Section I instead. Or, as moltenmetal suggested, B31.3.

 

[KevinNZ]

IdanPV, You have not stated what local laws apply.
Here, such a small system does not require coded design, The supplier can decide how to achieve a safe system.

 

[chicopee]

So you have a once flow through electric boiler. Check the scopes of power (ASME code I) and heating boilers (ASME code IV) to determine if your proposal is within one of the scope.