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J-Rod
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Location: Jamestown, North Dakota
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P-91 Welding

05/12/2010 6:58 AM

ASTM A335-09a, paragraph 9.3 specifies a hardness range for the finished materail (Post heat treatment), however, both ASME B31.1 and ASME Section I do not specify a maximum hardness for PWHT of the welds. Is there an industry standard (Refinery, Power, etc) that establishes a "best practice" hardness - range or maximum - for the weld and the HAZ after the PWHT? We have be getting hardness readings in the range of 230 - 275 Brinell, whereas the standard for the base material (per ASTM A335) is 190 to 250 HBW. I have not noted that either of the mentioned codes specify a hardness value for the PWHT condition of the work. Thank you for your kindness and response.

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Pathfinder Tags: QA/QC Welding P-91
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findstandard
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#1

Re: P-91 Welding

05/12/2010 11:41 PM

ASTM A335 / A335M - 09a Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service
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Rorschach
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#2

Re: P-91 Welding

05/13/2010 9:49 AM

If your weldment may experience H2S or hydrogen embrittlement, then NACE MR-0175 is probably one of the specifications you must meet and it places a maximum hardness at 22 HRc for most steels, including the HAZ of weldments.

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J-Rod
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Location: Jamestown, North Dakota
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#3
In reply to #2

Re: P-91 Welding

05/13/2010 3:28 PM

Thank you. That takes me in the right direction.

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PMoon
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#4

Re: P-91 Welding

05/14/2010 1:57 PM

My take is:

  1. If you purchased the materials with the required certifications and conducted any test you think necessary upon receipt, and...
  2. Fabricated the system, including all parts, components and appurtenances in accordance with the correct/applicable standards and specifications, and...
  3. Conducted all inspections and tests required by the correct/applicable standards and specifications.

then the hardness requirements of the original material in the heat affected zone or other area is not an issue or concern. I do applaud you for your effort to supply the correct quality item whether for your client of for your own facility.

I would invite others to comment on this as well, for I often need to be straightened out on these things.

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rbsantiago
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Join Date: Sep 2009
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#5

Re: P-91 Welding

05/30/2010 10:40 PM

J-Rod,

Usually the Client Specification specify the allowable hardness which you have to meet. Conducting hardness after PWHT at weld and HAZ area is to confirm that allowable range hardness of subject wasn't been altered and still in the boundaries of Hardness Range given by CS, if your weld or HAZ area hardness are not within this boundaries it means your PWHT is failure and subjected for rejection.
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findstandard
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#6

Re: P-91 Welding

05/31/2010 5:52 AM

I agree with PMoon
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