Can Standard Flanges Resist Full Bending Strength of Pipe?

[swearingen]

I'm using a piece of pipe structurally for something that needs to be disassembled. Least expensive way would be just to buy a flange and throw it in, right? The problem is, I cannot find any information regarding the global moment strength of a flange/flange connection. I feel that the moment strength of the pipe has to be a floor for flange design, but I don't see anything that specifically says that. Any help?

Pipe is 36"x0.750"

Thanks in advance...

 

[LittleInch]

Pipe flanges like B16.5 are designed to keep the fluid in. As such it's about having gasket compression enough to prevent leaks, not keep the flanges together.

Also the pipe could be very thick.

So I don't think it's part of the design for a pipe flange.

Structural flanges are different.

 

[KevinNZ]

Use the same procedure you would use for structural flange design but with pressure flange dimensions. Should be lower costs to buy a pressure flange compared to making a custom structural flange.

You could be conversate and use the flange calculations for sealing as the structural limit.

 

[goutam_freelance]

Some guidance may be available with ASME-VIII-1
MANDATORY APPENDIX 2-RULES FOR BOLTED FLANGE CONNECTIONS WITH RING TYPE GASKETS"

It is applicable "specifically to the design of bolted flange connections with gaskets that are entirely within the circle enclosed by the bolt
holes and with no contact outside this circle...."

The above rules do consider the moments applied to the flanges.

 

[LittleInch]

If you're going to do this use a flat flace flange and have no gasket if this is purely structural.

 

[dgeesaman]

I can say with some certainty that when a pipe with weld neck flanges is used as a shaft (low RPM rotating machinery, no pressure retention/fluid transmission) in very high cycle bending, it's less strong than the pipe itself.

There are other ways to connect flanges and make a shaft out of a pipe that return considerably more strength but those details are proprietary and there is still some stress concentration to be managed.

So is your load case static? Will it also contain pressure?

 

[LittleInch]

I missed that it was a 36" pipe....

You might want to look at flanges like TEMA has or B 16.47.

This looks quite interesting... https://www.mdpi.com/1996-1944/16/20/6815

 

[swearingen]

@KevinNZ - I think going with a circular base plate calc based on the flange dimensions is probably the way to go. Thanks.

@dgeesaman - no pressure and WAY down low on the S/N curve, so essentially static.