Number of bolt in a bolted flanged connection 4

[EmnaFati]

Hi
Can you help with this,
I used appendix Y of ASME VIII to calculate total required cross-sectional area of bolts of a bolted flanged connections. But I don’t how can I calcule the number of bolts or determine their size.
Thank you in advance

 

[marty007]

If you are working on a custom flanged connection, refer to Appendix 2.

The number and size of bolts must be selected for two conditions:
1) Gasket Seating
2) Operating Loads

 

[SnTMan]

Kind of a trial-and-error process. For a given bolt size there is generally a minimum required spacing. See TEMA or perhaps Machinery's Handbook, or other references.

Determine the bolt circle from flange geometry.

Check if you can get enough bolts on the circle to satisfy the required area. Often good practice to add four (or more) bolts.

If minimum bolt spacing is not met, increase the bolt size, bolt circle and have another go...

(Hint - if you cannot get enough bolts of a given diameter on the circle, decreasing the bolt size will not work)

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[pennpiper]

EmnaFati,
Your question sounds a lot like a School home work assignment.

- Why are you trying to design your own Flanges?
- Don't you know that Flanges of all sizes and pressure ratings are already available on the market?
- Don't you know that all of the dimensional data for these Flanges (and the matching Bolts) is available on the internet?
- Don't you know that your Flange must match up to other flanged objects (Valves, Strainers, Pumps, Filters, Vessel Nozzles, Instruments, etc) that already come with the industry standard Flanges?
- Don't you know the designing and using custom flanges on a system will raise the cost of the project?


Sometimes its possible to do all the right things and still get bad results

 

[Afox88]

Using custom flanges are very common for body flanges of medium to large tanks/heat exchangers/etc. Optimized custom flanges in many cases are much more cost efficient than standard flanges.

 

[pennpiper]

It sounds to me like "Afox88" is related to 'Beauregard Gustafson', that famous purveyor of misinformation.
see:

http://pipingdesigners.com/contents/blog/130-blog-1l-who-is-beauregard-gustafson

Sometimes its possible to do all the right things and still get bad results

 

[SnTMan]

Actually, Afox88 is correct. Custom girth flanges are extensively used in various clsses of work.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[marty007]

Yep, custom flanges are actually very common in equipment design, particularly for heat exchangers. I can see in piping where they would be pretty rare, but equipment is a different story.

 

[pennpiper]

So we are now assuming that EmnaFati the original poster was talking about a Custom 'Body' flange on a piece of equipment such as an exchanger or vessel and not a nozzle flange or an inline piping flange.
If so he (or she) did not make the question very clear.

Sometimes its possible to do all the right things and still get bad results

 

[SnTMan]

Yeah, an unclear post. Who'da thought

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[SPDL310]

Valve manufactures also design custom flanges for bonnet closures. Compact connection flanges are also designed for light weight ball valves used in some API applications. I don't know about the cost savings but the weight and size savings generally justify the costs for offshore instillations.

 

[MickMc]

Compact Flanges and Hub Connectors are as SPDL310 stated used extensively in offshore installations for both weight and space saving but are normally specified by purchaser to valve/equipment vendor who then incorporate into design with permission/assistance from selected compact/hub vendor as these are not standardised and differ slightly between vendors.

As for custom made flanges as a Piper I tend not to see much of these even on connected equipment unless the size/rating is outwith ASME B16.5/B16.47 and in the event that the equipment flange is custom made the vendor will be asked to provide counter flange along with calculations.

 

[lcatg]

I used App Y of ASME VIII.
I think the method is first to assume size and no of bolts,thus know the total actual c/s area, A_b.now calculate the total required c/s area A_m = W_m1/S_b.For safe design A_b>A_m.If its less we can increase no of bolts and size.

As others pointed out,there is a minimum spacing reqd between bolts.but in ASME i didnt see any condition like this.If you find please let me know.