NACE

NACE MR-01-75 for exploration & production (upstream)

NACE MR-01-03 for refinary (downstream)

Visit this site to know more
http://www.documentation.frco.com/groups/public/documents/articles_articlesreprints/nace_standard_mr103_bush.pdf

The difference is clear from the titles:

• NACE Standard MR0175 Standard:

Material Requirements Metals for Sulfide Stress Cracking and Stress Corrosion Cracking Resistance in Sour Oilfield Environments.

• NACE Standard MR0103 Standard Material Requirements:

Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments.

now NACE MR 0175 is NACE MR 0175 / ISO 15156 1-3. Look at the new version 'cause there are a lot of difference.

S.