Friday, October 24, 2008

Error in NACE MR0175 / ISO 15156

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NACE Standard MR0175 / ISO 15156 - Petroleum and Natural Gas Industries – Materials for use in H2S-containing Environments in Oil and Gas Production
was established to provides limits of H2S partial pressure for precautions against sulfide stress cracking (SSC) and guidance for the selection and specification of SSC-resistant materials.

If you refer to NACE MR0175/ISO 15156-2, Table B.1 - SSC laboratory testing for sour service, column 3 "Applied Stress", you will find "w 90 % AYS". See following image.



Now, refer to NACE MR0175/ISO 15156-2, Table B.3 - HIC/SWC test procedure and acceptance criteria, column 5 "Acceptance Criteria", you will find "CLR u 15 %", "CTR u 5 %" & "CSR u 2 %". See following image.




What is the meaning of
  • "w 90 % AYS"
  • "CLR u 15 %"
  • "CTR u 5 %"
  • "CSR u 2 %"
Infact these are errors in NACE MR0175 / ISO 15156-2. The"w" should be read as "≥" and "u" should be "≤". The correct text shall be
  • "≥ 90 % AYS"
  • "CLR ≤ 15 %"
  • "CTR ≤ 5 %"
  • "CSR ≤ 2 %"
Similar error occur in
  • Table A.3 in NACE MR0175 / ISO 15156-2,
  • Table, A.8, A.9, A.17, A.18, A.19...in NACE MR0175 / ISO 15156-3
Details refer to Errata in NACE MR0175 / ISO 15156.

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