Flat face and raised face

I've learned (or thought that I had learned) that it's O.K. to bolt a raised face piping flange to a flat face nozzle (on a centrifugal pump, for example) as long as the pump nozzle (casing, etc.) isn't made out of a metal that is easily cracked such as cast iron. Several major oil refineries have allowed this without any noticeable consequences. What are your thoughts on this?

 

[abeltio]

The codes (API650 for example) specify which are the allowable loads (forces and moments) on the equipment nozzles.
If the nozzle fails it is because the piping exerted too much force and moment at the nozzle (which obviously is a zone of concentrated stress due to the discontinuity it represents).
HTH
Saludos
a.

 

[Whe]

Mike,

The flat faced flange would need to be considered as working as a raised face. This may increase the stresses in the flat faced flange (potentially exceeding allowable stress or deflections: ie leaks).

Also a raised face gasket would be required, and you'd need to check the bolt-up requirements (may need a specific type of gasket to ensure reliable seal).

Regards,

 

[sprintcar]

Is there a comprehensive page that shows flange size, bolt size, bolt torque, etc for pipe sizes? API has flange layouts, but hopefully someone out there has put all the info on a sheet that could be emailed or faxed. Thanks! Keep the wheels on the ground
Bob
showshine@aol.com