A420 Gr WPL6 impact test temperature documentation & unit systems
A420 Gr WPL6 impact test temperature documentation & unit systems
(OP)
We are building ASME B31.3 piping for a compressor package where our customer has specified an MDMT of -50F for certain outdoor applications. We are using the typical materials A333 Gr 6, A420 Gr WPL6, and A350 Gr LF2 Class 1 for this system. Our QC department has raised a concern as the MTRs for some of this material specify the test temperature only in Celcius, at -45C (the specific example is A420 Gr WPL6). When this is converted to Fahrenheit, it's only -49F. However, the material specifications for the aforementioned materials all note that when material is ordered to the non-M version of the spec (i.e. A420, not A420M), the system of units is to be the inch-pound system, and temperatures would be specified in Fahrenheit. It also notes that converting between the two unit systems can lead to a non-conformance. The manufacturer's MTR specifies compliance to all four of A420, SA-420, A420M, and SA-420M.
I would interpret the requirements of that material spec to require the impact testing temperature to be listed in both -50F (to meet A420), and -45C (to meet A420M). Otherwise, I don't believe this material properly meets the listed specifications.
We are confirming with the customer if they would accept an MDMT of -49F instead of -50F, but if we aren't successful there, I'm wondering what the recommended way to resolve this issue would be. While we can go back to our supplier, and have them go back to the original manufacturer, I'm hoping we can avoid this somehow, as we have a lot of material that falls into this category, that's come from many different mills.
I would interpret the requirements of that material spec to require the impact testing temperature to be listed in both -50F (to meet A420), and -45C (to meet A420M). Otherwise, I don't believe this material properly meets the listed specifications.
We are confirming with the customer if they would accept an MDMT of -49F instead of -50F, but if we aren't successful there, I'm wondering what the recommended way to resolve this issue would be. While we can go back to our supplier, and have them go back to the original manufacturer, I'm hoping we can avoid this somehow, as we have a lot of material that falls into this category, that's come from many different mills.
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RE: A420 Gr WPL6 impact test temperature documentation & unit systems
I would have asked for -55F.
And yes, if your order said -50F then they obliged to report in "F".
They can also show as many other sets of units as they want to, but the one that you asked for must be one of them.
I hope that they didn't do this also with thickness.
In ASTM those are not hard conversions, and it is easy to make a size that doesn't meet both M and non-M.
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RE: A420 Gr WPL6 impact test temperature documentation & unit systems
Note that B31.3-2020 Table A-1M lists the minimum temperature for A420 WPL6 as -46°C (-50.8°F). This is lower than both the -45°C and the -50°F shown in A420. A reasonable person will accept that ASTM and ASME have divergent views on whether -50°F is equivalent to -45°C or -46°C and that it doesn't matter in service.
-50°F is the specified impact test temperature in A420 for WPL6. Asking for -55°F would make it non-standard A420. ASME B31.3 Table A-1 lists the minimum temperature for A420 WPL6 as -50°F.
If you want to push this back on your material suppliers, check whether you ordered A420 or dual-certified A420/A420M:
If you only ordered A420, they should give you MTRs that conform to A420. Hopefully their testing conforms to both A420 and A420M, and they'll be able to give you an A420-conformant MTR. However, if you ordered A420/A420M, then they likely conformed to the order requirements if they reported all results in SI units, but maybe they can still give you an MTR with inch-pound units reported.
RE: A420 Gr WPL6 impact test temperature documentation & unit systems
RE: A420 Gr WPL6 impact test temperature documentation & unit systems
SWComposites, get your point, but you absolutely know the accuracy of any measuring items during the test. Calibration reports will tell you.
This is somewhat silly.....even for engineers.
RE: A420 Gr WPL6 impact test temperature documentation & unit systems
Overall, I agree that this was a bit silly, but sometimes these small silly things end up holding up a lot of things until they are resolved.