3-Bolt Flange Design
3-Bolt Flange Design
(OP)
Can someone pleae adise me on what ASME code to use for the design of a 3 bolt, class 150 flange.
I have looked into ASME Sec. VIII, Mandatory Appendix 2, but it does not ask for the number of bolts, which leads me to belive that you may not be able to design for a 3 bolt flange using this standard.
Thank you,
Alex
I have looked into ASME Sec. VIII, Mandatory Appendix 2, but it does not ask for the number of bolts, which leads me to belive that you may not be able to design for a 3 bolt flange using this standard.
Thank you,
Alex





RE: 3-Bolt Flange Design
There seems to be a fundamental problem in your understanding the scope and structure of the Codes and Standards.
When an ASME Class 150 flange is used as part of a piping system or pressure vessel, the designer is restricted to the dimensions, bolt configurations and pressure/ temperature limits given in the Standard.
When a designer wants a "unique", one of a kind flange for his particular application, he can use the complex rules of ASME VIII, Appendix 2.
I know of no previous case where a "three bolt" flange was used in either a piping system or as an ASME B16.5 flange.
-MJC
RE: 3-Bolt Flange Design
RE: 3-Bolt Flange Design
Why would you possible want to design such an ODD flange?????
The other question how are you going to match up to four bolt flange configurations on Valves, Gaskets and Equipment.
If you really want or need such and ODD configuration, then you had better have a lot of money because you will need to create all the related connecting items in the same configuration. This means not only for the original installation but for replacement during the 25 to 30 year life of the plant.
This does not sound like a good idea to me.
RE: 3-Bolt Flange Design
RE: 3-Bolt Flange Design
RE: 3-Bolt Flange Design
I would guess that the reason to go to a 3 bolt flange is installation expense. Noting that alex's tag identifies him as "nuclear" there is a good likelyhood that the installation of this flange will be by robots in a "hot" environment. Ever wonder why nukes ar so expensive? In the process world that I'm used to we can inspect our pipes and equipment almost anytime and repair options are relatively plentiful. In the nuclear world, those options are severely limited. Different environment, different cost structure.
alex-
I'd suggest that you are not in VIII Div. 1 Appendix 2 territory, but in FEA land. Keep in mind that meeting the allowable stress will be relatively easy - its the deflections that will get you. I'd also poke around a bit at the offshore industry - they may have devices you can use or at least get inspiration from.
jt
RE: 3-Bolt Flange Design
If I recall correctly there were also some weldneck flanges in their brochure.
RE: 3-Bolt Flange Design
This assumption is valid for even and close distribution of bolts. The further away from this assumption you get the less valid the underlying assumption.
In my opinion jte is correct in guiding you towards an FEA analysis. Stress is not likely to be the governing criteria; deflections and the associated loss of sealing in between the bolts are going to be your headache.
If it this was my project I would initially size the flange based on Section VIII app 2 (making damn sure I had planty of margin on the rigidity criteria), I would then perform an FEA analysis on 1/3 of the flanged joint (making use of symmetry) to evaluate deflection due to only having three bolts. I would then interface with a gasket vender to find out what would be acceptable and compare. This will be no easy feat and can easily take up a lot of time and energy. Especially if you don't have a good FEA person around
Just my two cents worth
Always remember, free advice is worth exactly what you pay for it!
RE: 3-Bolt Flange Design
Why not copy the existing flange?
RE: 3-Bolt Flange Design
RE: 3-Bolt Flange Design
RE: 3-Bolt Flange Design