human909
Structural
- Mar 19, 2018
- 1,971
Hi all, Second time this week I've reached out on what is a pretty basic question but it is something outside my normal experience. As I said in the last post feel free to flame away on me, an engineer who is poking his head outside his normal area of competency.
Background: A client approached me with a problem. I'm likely to offer guidance and a suggestion to consult an engineer more experienced in the area, I'm not sure it is worth the risk for me, but it is a good client so I'll offer some friendly guidance on where to seek a solution. Regardless the topic has perked my interest.
The problem:The client has fabricated a bunch of pipework for compressed air with flanges rated for 7bar. The client has now found out that the the customer scope included the option to upgrade the pressure beyond this I believe up to 10bar. The fabricator doesn't want to cut and reweld dozens (possibly hundreds) of flanges and is looking for a solution.
(Under the relevant code AS 2129 it specifies specific flanges for specific pressures/temperatures. These all have predefined dimensions etc.. As I understand it ANSI has similar guidance.)
My questions:
Using some preliminary basic engineering analysis it seems to me that pipe flange design is largely dictated by deflection and sealing requirement rather than yielding or material failure. Is this correct?
One obvious solution that occurs to me is to have half circle flanges to double up the flange. If it is thick enough then deflection and strength criteria seem to be satisfied. Does this make sense?
The bit I don't know enough about is the local code requirement. Eg even if it works from a engineering perspective it still might not comply. Hence I'll probably stay away from the job. It likely isn't worth my time, but it does interest me.
Background: A client approached me with a problem. I'm likely to offer guidance and a suggestion to consult an engineer more experienced in the area, I'm not sure it is worth the risk for me, but it is a good client so I'll offer some friendly guidance on where to seek a solution. Regardless the topic has perked my interest.
The problem:The client has fabricated a bunch of pipework for compressed air with flanges rated for 7bar. The client has now found out that the the customer scope included the option to upgrade the pressure beyond this I believe up to 10bar. The fabricator doesn't want to cut and reweld dozens (possibly hundreds) of flanges and is looking for a solution.
(Under the relevant code AS 2129 it specifies specific flanges for specific pressures/temperatures. These all have predefined dimensions etc.. As I understand it ANSI has similar guidance.)
My questions:
Using some preliminary basic engineering analysis it seems to me that pipe flange design is largely dictated by deflection and sealing requirement rather than yielding or material failure. Is this correct?
One obvious solution that occurs to me is to have half circle flanges to double up the flange. If it is thick enough then deflection and strength criteria seem to be satisfied. Does this make sense?
The bit I don't know enough about is the local code requirement. Eg even if it works from a engineering perspective it still might not comply. Hence I'll probably stay away from the job. It likely isn't worth my time, but it does interest me.