Casting Requirement ASME VIII-div2

[oelindoe]

Hi guys. Im a novice to the ASME calculations and during a current job i've run into some problems... Hopefully someone can advice

Im doing a subsea flowmeter which consists of a inner venturi spool with various sensors. In order to protect the flow sensors electronics, an external housing is attached by welding to the inner flowspool end flanges. i.e the whole thing is defined after VIII-div2.

For practical reasons the external housing is prefferably made of casting. The cast manufactor has many feasible qualities we want to use, but they are not ASME approved.

The external housing is indeed a pressure vessel, but it is only a protective housing under static seawater pressure loading. All strength calculations for the housing follows the code.

What would be the next step for me now in order to follow VIII-div2?. Does the cast material have to be approved by ASME or are there any shortcuts (i.e verify ductility,hardness,NDT,etc)

Any advices ?

 

[gr2vessels]

oelindoe,
The ASME VIIII Div 2 has allowed a list of materials, including the castings, listed in the Section II, Table D. The welding of castings is not restricted in the Div. 2, but you have to follow closely the Section IX and the relevant Div. 2 recommendations.
This is a broad reply to your vague enquiry. The specifics depend on the materials joined, compliance with other requirements like corrosion resistance, fabrication requirement, etc..Also, depending on the local government requirements or insurance requirements, you might have to provide U2 stamping, which requires additional documentation and fabrication requirements in accordance with ASME VIII Div. 2. Make sure to ask specific questions from this forum, your PE and any other person familiar with the design and fabrication of Div. 2 vessels in order to soak up as much as possible knowledge. It's the only way to further your career and broaden your experience.
Good luck,
gr2vessels

 

[oelindoe]

Thanks Gr2. So in order to make the housing VIII-Div2 approved, i must use a material listed in sect.2-tableD. There are no exceptions to this rule ?

Another question.. Is it possible to define a code break for an assembly. i.e we keep the internal flowspool on Div2 while using a less strict code for the external housing & welds ?

 

[gr2vessels]

The ASME code has listed the materials allowable for use under the its jurisdiction. Other materials may be used, if the ASME equivalency can be proved and certified.
The ASME code allows the combination of vessel components ( like Div 2 and Div 1 - refer Clause 1.2.5 of ASME VIII Div. 2), subject of divisional limitations.
best regards,
gr2vessels