ASTM G48A - length of test period
ASTM G48A - length of test period
(OP)
ASTM G48 method A suggests that 72hrs is a reasonable test period. All the specs that we have previously worked to have a test period of only 24hrs (Norsok, Shell, ExxonMobil etc)
Does anyone know of a spec that insists on a 72hr test period? We have a client who has an ongoing internal debate on whether to change their data sheets.
Does anyone know of a spec that insists on a 72hr test period? We have a client who has an ongoing internal debate on whether to change their data sheets.





RE: ASTM G48A - length of test period
For well conducted tests the 24hr and 72hr results are identical. This has been proved for methods C, D, E, F, but I have never seen such data for A and B.
Of course I would also suggest the use of Method C. The results from A are much more erratic.
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Plymouth Tube
RE: ASTM G48A - length of test period
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: ASTM G48A - length of test period
SJones - At the moment, cast super-duplex stainless (ASME SA995 6A), but it may be extended to other materials.
RE: ASTM G48A - length of test period
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: ASTM G48A - length of test period
I really dislike using the original non-acidified test solution. It can vary considerably from one batch to another.
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Plymouth Tube
RE: ASTM G48A - length of test period
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: ASTM G48A - length of test period
Because our clients ask for G48 method A plus charpy-impact testing, usually at -46C, plus micro-examination & ferrite count to ASTM E562. They, in turn, are driven by the requirements of their clients.
RE: ASTM G48A - length of test period
The A923 requires a freshly ground surface to reveal any secondary phases that may be present. The temperatures are well below the critical pitting temp for the given alloys. The goal is to see if there is corrosion due to secondary phases in the structure.
G48 is used as a guide to determining or verifying the critical pitting (or crevice) corrosion temperature of a sample. We use G48C on finished tubing, no surface prep of any kind is allowed (strictly as shipped), and we fix time and temp. We expect 100% to pass this test as it is about 10C below our historically determined CPT.
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Plymouth Tube
RE: ASTM G48A - length of test period
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: ASTM G48A - length of test period
A923 is being continually reviewed and revised. New alloys are being added and errors fixed. Someone trying to work with duplex grades could not ask for a better spec to work with.
Writing a spec does not end your work, it only begins it. A spec that hasn't been revised in five years is not worth using. I have been known to quote jobs with separate price adders for various testing. I can send a message that way.
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Plymouth Tube