Surface Roughness
Surface Roughness
(OP)
Hi,
Could someone tell me (or point me at a resource or standard) that can identify the difference between surface roughness measurements Ra and AA (Average Roughness). I have values in both scales, and need to compare them for a model I am building.
Could someone tell me (or point me at a resource or standard) that can identify the difference between surface roughness measurements Ra and AA (Average Roughness). I have values in both scales, and need to compare them for a model I am building.





RE: Surface Roughness
http:/
Rao Yallapragada
RE: Surface Roughness
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Surface Roughness
First to Yallapragada1022, that link doesn't work for me.
Second to EdStainless, let me further explain my problem. I am using a thermal hydraulics program that requires surface roughness for piping materials, or any metal surfaces over which fluid my flow. We are using French mechanical drawings that specify stainless steel component roughnesses with a default surface roughness of 6.3 micros Ra. I am used to working with american drawings where surface roughness is specified in average roughness. I know that the code asks for absolute roughness which is equivalent to 2 times the AA or 1.8 times the RMS. I am not sure how to convert Ra into absolute roughness, but from what I have read, think that Ra is similar to AA in regards to piping materials.
Does this help?
Eventually the roughness is used in a fit of a Moody diagram to calculate friction loss (pressure loss) in the fluid system.
RE: Surface Roughness
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Surface Roughness
the pdf says in the first alinea: Ra or Roughness Area (also known as CLA and AA).
Which means: exactly the same...
IJsbrand
RE: Surface Roughness