Maximum design pressure for Vessel design on sct VIII DivI 1

[FAhmed]

I got a request for quotation for a Pressure Vessel. The design pressure is 5000 psi and required for Lethal service. I reviewed the ABSA website and found that ASME section VIII Div I is normally up to 3000 psi. Also found statement in ASME section VIII Div I U-1(d) (Introduction), applicable to Vessels designed for pressure not exceeding 3000 psi

Will you kindly clarify this to me.

Thanks

 

[vesselfab]

I think it says, over 3000 you may have to deviate a little but yu can still stamp it. I think if it were me, I would be looking at Division 2 instead of div 1

 

[CodeRef]

vesselfab is correct,
The rules of Section VIII-1 were formulated primarily for vessels intended to operate at pressures of 3000 psi less. If you use VIII-1 instead of VIII-2, that is your choice as a designer. Remember that if you choose to use VIII-1 as the design basis, the vessel must comply with all of the requirements of this Division before it may it be stamped with the applicable Code Symbol Stamp.
As always, consult with your AI


There are three kinds of people in this world; those who can Google and those who can't.

 

[EGT01]

Pressure vessel design is not my area of expertise but I thought I would mention this in case it might apply... I have seen compressor pulsation/gas storage "bottles" that were stamped over 5000 psi but were constructed according to ASME Sec 8, Div 1, Appendix 22 Integrally Forged Vessels. So maybe there is something in Part UF that would be worth reviewing as well.

 

[vesselfab]

fahmed...since the Lethal service is a requirement, all the things you do for that, is what you do in div 2 for any vessel, so div. 2 and it's extra NDE/Fab requirements are not detrimental to budgets. Div 2 is much more suited to the heavy wall vessels. Hopefully you have a Div. 2 stamp.

 

[FAhmed]

I appreciate all of your feed back. Still awaiting Design Eng response from ABSA. I would check appendix 22 and part UF. Unfortunately our shop is not qualified for Div 2.

Thanks for the help.

 

[gr2vessels]

Fahmed,
The pressure vessel design is based on calculating the minimum required thickness for a every component retaining pressure and that minimum thickness is obviously proportional to the design pressure. That is, the higher the design pressure is, the thicker is the minimum required thickness. The ASME code has made provisions for a reasonable engineering design, for the most common materials used in the industry. It has been established that the Division 1 method of design is most economical and sufficiently safe up to around 3000 psi. Above that pressure, the design method may not be as economical as it should be, hence a Division 2 method of design has been created, to help the design engineers, fabricators and end users to build a safe equipment, but allowing some thickness reduction in comparison with Division 1 by applying more stringent design/fabrication/testing requirements.
Nothing will prevent you designing and stamping your equipment subject of 5000 psi pressure to Division 1. However, it could be more feasible for you to take advantage of the Division 2 allowances.
This days, if in doubt, you can run some quick numbers on the major components of your vessels, to estimate if the design to Division 2 would be beneficial to you (or to estimate the losses if you will use the Division 1 instead of Division 2. I assume that you are using some PV Elite software or similar. As per the above, you could quote on the Division 1 basis, but you might not be competitive as the Division 2 fabricators.
cheers,
gr2vessels

 

[MJCronin]

Fahmeed..

Out of curiosity, what is the contents of the vessel and on what design basis are you designating it "Lethal"...???

-MJC

 

[eliebl]

I do not recall where I heard it but the 3000 PSI reference is also intended to limit the wall thickness to thicknesses to those which are readily radiographable.

 

[TGS4]

The 3000psi limit is one where the "thin shell" thickness equations are valid and appropriate. Beyond that, you need to use a different set of thickness equations (think Lamé). You're probably going to end up doing a U-2(g) evaluation for the entire vessel since the equations are not appropriate for your pressure. If I were you, I would decline to bid...

 

[LSUME]

I'm relativeluy new to ASME Sec VIII, but wouldn't Sec VIII Div.3 be more appropraite for this vessel?

 

[vesselfab]

??

 

[TomBarsh]

I have seen a number of vessels designed to Div 1 for pressure > 3000 psi. Many of these were installed in Alberta and registered with ABSA. From what I've seen, this practice seems fairly standard for certain vessel applications.

I have attended several classes or seminars that were taught by members of ASME Code Committees (including one fellow who was on the Division 3 committee for extremely high presssures) where it was also said that Division 1 does not prohibit pressures above 3000 psi.

Use of Division 1 for high pressures may result in excessive thickness as compared to other design Codes. Use of Section VIII Divisions 2 and 3 could result in lesser required thickness, but they will also result in more extensive testing and QA requirements. Depending on the complexity of the vessel, a Div 1 design might be more economical than a Div 2 design, or vice versa.

I suggest discussing with ABSA before proceeding, or before declining to bid.

 

[jte]

Div 3 would probably not be the most appropriate for this situation. From the Scope paragraph:
The rules of this Division constitute requirements for the design, construction, inspection, and overpressure protection of metallic pressure vessels with design pressures generally above 10 ksi (70 MPa). However, it is not the intent of this Division to establish maximum pressure limits for either Section VIII, Division 1 or 2, nor minimum pressure limits for this Division.

Although it could go Div. 1, Div. 2 would most likely be a better application. The question then becomes "new" or "old" Div. 2?

jt