Determining acceptable charpy impact values

[bill8123]

So we select materials strength criteria based on calculated stress, factors of safety and yield stress values.

So what about the toughness criteria, how do we determine the minimum charpy impact value required for a given design?

 

[IFRs]

The design metal temperature is a good start when looking a toughness.

 

[IFRs]

Sorry - hit send my mistake. I find minimum values in the code I am designing to.

 

[SJones]

Chapter 13 in

http://www.astm.org/DIGITAL_LIBRARY/MNL/SOURCE_PAGES/MNL41-3RD.htm

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[redpicker]

So we select materials strength criteria based on calculated stress, factors of safety and yield stress values.

So what about the toughness criteria, how do we determine the minimum charpy impact value required for a given design?

In a word: Experience.

Find a similar design and use the value that worked for that design.

From a practical standpoint, I've seen two methods.

1) If you are responsible for the design and manufacture, find the best comparable design and use that value.

2) If you are responsible for only the design and not the manufacture, find the best comparable design, double it and drop the test temperature at least 10 degrees.

rp

 

[bill8123]

Thanks Guys. My suspicions were correct.

 

[weldstan]

The required absobed energy values are primarily based on material strength, thickness, and applied stress as a percentage of minimum yield strength. In gas pipelines you also need to consider ductile shear arrest.