Hi all,

For a forged elbow (SA234 WPB), do we need to apply equations 3c, 3d or 3e in sec 304.2 of ASME B31.3 for elbow wall thickness calculation? Or we can just use the same thicknees as straigth pipe?

Thanks,

Paragraph 303 states "The rules in para. 304 are intended for pressure design of components not covered in Table 326.1..."
If your forged elbow was manufactured in accordance with ASME B16.9 you can accept the temperature-pressure limits for your Class and need not check the wall thickness for pressure.
Equations (3c),(3d),&(3e)are for bent pipe "after bending", not forged elbows.

Dave,

Somehow I couldn't find any temperature-pressure rating charts/limits in B16.9 (07 Ed.), maybe B16.9 refers T-P to some other codes?

Bryan

If I'm not mistaken B16.9 says that you can use a maximum pressure for the fittings of 80% of the maximum pressure for a straight pipe with the same wall thickness.
But this is somewhere from the very back of my head so don't trust this information.
I know it's hidden in the B16.9 somewhere.

Quote from B16.9 - Chap. 1, Scope:

1.10 Pressure Rating Designation
Class, followed by a dimensionless number, is the
designation for pressure–temperature ratings. Standardized
designations for flanges per ASME B16.5 referenced
in this Standard are Classes 150, 300, 600, 900, 1500,
and 2500.

So the elbows, 180, etc., goes by the B16.5 T-P chart?

Dave or anybody could shed some lights?

Try reading Paragraph 2.

Butt-welding elbows are not sold with pressure ratings, so why would you think that the paragraph you cited had anything to do with elbows?

You should all note that elbows and other (forged) fittings that are sold with pressure ratings are under B16.11, not B16.9.

Anything sold under B16.9 is not normally associated with a pressure class, despite Paragraph 1.10 of that standard.

The authority for the rated pressure limit for a butt-welding elbow is B31.3 Paragraph 302.2.2.

I knew it was related to straight pipe somewhere. Apperently 87,5% and noted in B31.3 instead of 80% and noted in B16.9 as I stated above.