ASME VIII Div 2, Do I conform with 'lethal' service anyway?

[jimmytimpleton]

I am working on a project where we are looking to get a 10,000psi rated vessel manufactured in A-182 F22. The design and manufacture will be in accordance with ASME VIII Div 2. The vessel consists of a 70mm thick body with two 70mm thick nozzles welded onto the ends by means of 2 butt welds.

The vessel is to be used for natural gas applications and there is a likelihood that H2S maybe present. We are content however, not to class the vessel as ‘lethal’ as described in Div I, UW-2.

If I read correctly, if the vessel was to be classified as ‘lethal’, then the following must apply:-

1) Full Radiography on the butts (Radiography can be substituted by UT due to 2007 changes)
2) The requirement for PWHT.

However as it stands, the vessel and corresponding nozzles have a wall thickness of 70mm. From Div I, UW-11, this suggests that full radiography/UT as the nominal thickness at the welded joint exceeds 11?2in. (38 mm).

Secondly, from Div I, UCS-56, the requirement for PWHT on A-182 F22 already exists.

Am I therefore correct in saying, that although we do not want to class the vessel as ‘lethal’ service, we will still be undertaking the two requirements that ‘lethal’ service brings due to the material chosen and the thickness of the design?

 

[TGS4]

If you are performing the design and manufacture in accordance with Division 2, then why are you referencing Division 1 paragraphs?

If this is truly a Division 2 vessel - do you have a professional engineer who is capable or is able to certify your Users Design Specification? Once the UDS is completed, then a fair number of these questions will become clear.

 

[vesselfab]

no

you are pwht the vessel due to thickness/material

you are doing radiography because div says full radiography


lethal service has other requirements other than these two.


no....you don't have to call the vessel lethal service as long as the concentration of h2s is not lethal and the user's safety program and insurance comany will buy it that way.

They will run it through HAZOP and check it out.

and yes...you do have to create a User's Design Specification with all the pertanent information required by the code for the manufacture to do his report and manufacture the vessel.

why not use Div 1 if you are not qualified to spec out a div 2 vessel.

or specify div 1 and div 2 as an option

 

[jimmytimpleton]

Thanks for the response guys.

As you can probably tell from my initial question, I am not up to speed with this code and to be honest I am even more confused now. I personally wont be involved in the design (this will be done by qualified engineers) but was hoping for a clearer picture for my own benefit as I will be liaising with the Third Party Authority throughout.

I read some correspondence that states that Div 1 is only suitable where 15 psig < P < 3000 psig, with P being the design pressure. Judging by your response however, even though our design pressure is 10000 psig you state that we can still conform to Div 1. requirements. Is this correct?

Also, Div 2 does not mention ‘lethal’ service at all. I presumed we would therefore have to fall back on what Div 1 says about this anyway,you state that ‘lethal’ service has other requirements other than just PWHT & Radiography. Can you please advise me on what these are?