ASTM A358 Out-of-Roundness

[Deanlover]

Dear All,

I'am confused about the Out-of-Roundness description in ASTM A358.

My understanding is following:
Out-of-Roundness (ODmax - OD min) ≤ OD*1%, for instance, pipe norminal OD is 168mm, and after measuring, the ODmax is 168.8mm and ODmin is 167.9mm, so the out-of roundness=(168.8-167.9),which shall not exceed 168*1%

Is my understanding correct?

Thanks in advance.

 

[EdStainless]

The OD is the average OD, such as you would measure with a pi tape.
The ovality (out-of-round) is comparing min and max point diameters at any one cross section.
So with 168mm nominal OD the average can be +/-0.8mm from that.
If you use a micrometer and check at any given the location the min/max readings must be 166.3 - 169.7mm

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P.E. Metallurgy