BPV Sec8 Div 1 vessel SA-36 or SA-516-70? 4

[MylesD]

I have a coded fired steam boiler that I am building and my firebox flange should not technically retain any pressure but I have to consider it pressure retaining anyway. The original BOM has my material at SA-36 (.75" thick) receiving only 150F temp operating and 75lbs of pressure design. The code book is somewhat longwinded. I want to use SA-36 on what will be considered a pressure retaining flange- is this kosher by ASME or should I just go with SA-516-70? I know the SA-516-70 is a sure shot to comply to code, but I am also looking at cost. This will be on several vessels so its not a one time expense. Any feedback is appreciated.

 

[EnergyMix]

The code book is somewhat longwinded.

It would be worthwhile to read it anyway.

 

[MylesD]

I have read it, and I do appreciate the advice, however my part in question seems to fall into a somewhat grey zone. It is a very specific situation that I have not encountered yet and I have my background and gut feeling telling me to go with SA-516-70, but I still economically need to pursue SA-36.

 

[metengr]

No, SA-36 is not permitted to be used as flange material. Flange material is covered under ASME B16.5.

 

[MylesD]

Thanks for the heads up. I can not seem to locate my 16.5 anywhere which is why I have been operating somewhat blind for the past few hours and trying to comb through the Sec8 Div1 book was getting me nowhere.

 

[prex]

SA-36 would be allowed under VIII Div.1 coverage, but it is not by ASME I.

prex
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[metengr]

Section VIII, Div 1 is not applicable for a "coded fired steam boiler". Second, see UCS-6 (2) even for unfired steam boilers, SA-36 is not permitted.

 

[MylesD]

I did see the UCS-6(2) and did read the part about unfired, but it never makes mention about fired- i know that one should draw a logical conclusion based off of an unfired not allowing it but I did want to get outside opinions

 

[metengr]

Fired steam boilers are under Section I domain.

 

[stanweld]

MylesD,
Are you sure that this hot water heating boiler with design temp of 150F at 75 psig is not under ASME Section IV, which does permit the use of SA-36? Do you even have an ASME Certificate of Authorization for manufacturing these boilers? If in the USA, you must manufacture/sell boilers to the Local (generally State) Jurisdiction requirements.

 

[MylesD]

Stan
I do have an ASME Certificate of Authorization. We have never used Section IV, we have always used Section VIII, our AI goes by the Sec.VIII guidelines. I am new to the Quality Control aspect of this job. Is there a provision of Section IV that I should be looking at? The only Code books I have are Sec VIII and it seems to cover what I am building.
Thanks

 

[stanweld]

If your Company only has a U Certificate, you may not manufacture the fired boiler. The U Certificate may be used for unfired boilers - not fired boilers. If your Company has an S-Certificate, you may Manufacture water heating boilers per PG 2.2.

Your Company would need an H Certificate to manufacture heating boilers under ASME Section IV. HG-540.7 of ASME IV defines provisions for when a Manufacturer may start fabricating Section IV items before reciept of the H Certificate. If your Company wishes to be in the business of manufacturing water heating boilers, I advise that they apply to the ASME for the H Certificate.

 

[MylesD]

Stan,

Does it matter what type of fired process that the treater will be used for? It is a fired treater to treat oil, not just water. My inspector is coming over later today to look at a different type of vessel and I will get with him, but if you have some insight into this, the inspectors usually try to get in and get out with not much context.

So I guess my question is: Does any fired pressure vessel fall under that section if water is involved?

Thanks
Myles

 

[stanweld]

Take a look at U-1(c)(2). You will also need to review the Jurisdiction requirements for the equipment to be sold. You may not be able to sell your hot water heating boilers in all or any of our States/Municipalities with a U Stamp.

Your oil heater can meet U-1 (a)(2) and be stamped accordingly.

 

[chaulklate]

Myles, I'm going to look at this from a different perspective, with respect to all above...

Your exterior firetube flanges are not pressure retaining, nor are they regulated by ASME code. One of the flanges has to be designed mechanically to withstand the loads from your flame arrestor (or firebox, whatever you are calling it),and the other flange needs to be designed to withstand the loads from your stack. Neither has to be designed for pressure. The SA-36 is acceptable material. The firetube proper needs to be designed for external pressure equal to the treater design pressure, be able to externally withstand the hydrotest pressure, and be made from Section II materials (516-70N or 106B for example). You also do not need to apply the rules of B16.5 for this configuration. If you want a guideline for design, use Appendix 2 with a relatively low pressure (50 psig??). I would not consider this to be a 'fired' vessel as the flame is indirect, nor would I consider it a boiler of any kind. All you are doing is indirectly heating the oil/water medium to accelerate separation.

Or, at least that is what I was able to pick out of your post. I could be wrong.

 

[MylesD]

Very true... there is no "direct fire" of the medium in this case, even though that is what it is termed at our company. I have gotten with my inspector and he has said the same about the flange, that since it is outside of the actual vessel, it does not need to retain pressure nor meet any certain spec on material. This specific treater is going to be using oil only, change in request from customer. Because of its size they want one for oil and a boiler of the same shape for water, but for now I am looking only at the oil as that is the first on the drawing board. The pressure is a max at 75 psig so it is low pressure.

My biggest obstacle is that I have been working in the chemical industry for years and I am just recently a QCM at a pressure vessel company. While I am a mechanical engineer, ASME code is just difficult to get right everytime in every situation when I have NEVER encountered any of these particular situations prior. I dealt with thermal flow in a chemical process, not weld sizes on SA-105 pipe. So this is a big learning experience for me.

Any advice that can be given would be greatly appreciated..

Thanks
Myles

 

[metengr]

MylesD;
Follow the advice of your Inspector. If they belive this flange is outside of the boundary for Section VIII, Div 1 or Section I design rules, the flange and MOC should be based on prudent design, and proper selection, respectively. Based on the information from your Inspector, SA 36 material could be used.