Saturday, October 25, 2008

Material Selection... USER Responsibility

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This is a brief history about how NACE MR0175 / ISO 15156 is established since 1950s. It begun after World War II with the establishment of Technical report 1A152 "Sour Oil Well Corrosion" and 1B159 "Well Completion & Corrosion Control of High Pressure Gas Wells" when the demand to gas increased. This followed by NACE 1B163 "Recommendations on Material for Sour Service" and NACE 1F166 "Sulfide Cracking-Resistance Metallic Material for Valves for Production and Pipeline Service" in 1960s. First published of MR 0175 in 1975 and TM0177 "Testing of Metals for Resistance to Sulfide Stress Cracking at Ambient Temperatures" in 1978 and followed by TM0284 "Evaluation of Pipeline Steels for Resistance to Stepwise Cracking" in 1990. MR0175 is then merged with some EFC reports i.e. EFC#16 & #17 and finally first published the NACE MR0175 / ISO 15156 in 2003/2004.

Critical Improvements
Several critical improvements in the NACE MR 0175 with the published of NACE MR0175 / ISO 15156 in 2003/2004 :
  • Inclusion of Stepwise cracking (SWC), Stress Oriented Hydrogen-Induced Cracking (SOHIC), Soft-zone cracking (SZC), etc. Read more on these corrosion type in "What are the concerns related to H2S ?"
  • USER who are specifying and/or operating the equipment has full responsibility to ensure a material is works satisfactory in the intended environment. USER is responsible for the material selection. On the other hand, MANUFACTURER is responsible for meeting the metallurgical requirements.
  • For revamping/modification of existing facilities and the material was designed for previous revision of NACE MR0175, if USER has the opinion the fluid condition stayed as before, USER may keep the existing material.
  • NACE MR0175 / ISO 15156 is solely a guide documents for a proper selection of material in H2S environment. This documents providing list of material resistant to H2S environment, however, the material is not immune to to H2S environment. It implies that improper design, selection, fabrication, etc. may still lead to these material susceptible to H2S environment.
USER Responsibility
From above statements, the use and implementation of NACE MR0175 / ISO 15156 in H2S environment is within the decision of USER. A metallurgist and material engineer with the assistance of process and chemical engineer within the USER group i.e. COMPANY, CONTRACTOR, and LICENSOR are playing a major role in defining and implementing this standard. DO NOT RELY ON MANUFACTURER & VENDOR !!!

Read more in "Changes to NACE Standard MR0175-2003"
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