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SA-182

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loilfan

Mechanical
Jan 20, 2015
122
We are trying to design a fitting that is used as a mixer to ASME VIII, Div 1. It is bolted together and is not part of a piping system as it is used in a testing facility. It has various ports in it and the mixer/mixer shaft so we are not able to use standard components.

We were looking at using SA-182 F316, but the ASTM standard for SA-182 in Sec IIA references SA-961 "Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications". SA-961 6.1.1 says "Bar - Flanges, elbows, return bends, tees, and header tees shall not be machined directly from bar."

Why is SA-182 F316 an acceptable material for a flange as per B16.5, but is an unacceptable material if we machined a flange-like component?
 
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Because rolled bar material can contain internal defects (inclusions) depending on cleanliness that can open to the surface and result in leakage in service.
 
SA-182 is a forging specification, and therefore acceptable. Please review the specification titles which refef to the product form.

Regards,

Mike
 
Thank you for your quick responses, metengr and SnTMan.

The definition of a bar in SA-961 is "a solid rolled or forged section that is long in relationship to its cross sectional dimensions, with a relatively constant cross section throughout its length and a wrought microstructure".

From this definition it reads to me that a forged piece, whether rolled or not, can still be considered a bar if it is long compared to its cross section.

It makes sense to me that a rolled bar is not acceptable because it has an elongated microstructure and inclusions, but a forging that happens to be long in comparison to the cross section would not have these issues.
 
In SA 182 reference to the following is

6.4.1 Flanges of any type, elbows, return bends, tees, and
header tees shall not be machined directly from bar stock.

Bar stock is not forged bar, it is rolled bar.
 
Further
SA 788

Discussion—Because of differences in manufacture,
hot-rolled, or hot-rolled and cold-finished bars (semi-finished
or finished), billets, or blooms are not considered to
be forgings.
 
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