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What Is NACE MR0175 / ISO 15156?

What is it Nace?

The document commonly known as “NACE” originated in 1975 from the National Association of Corrosion Engineers, now called NACE International. NACE MR0175, officially titled “Petroleum and Natural Gas Industries — Materials for use in H2S-containing environments in oil and gas production,” set recommendations for H2S threshold limits requiring precautions against environmental cracking. In 2003, a similar document, NACE MR0103, was introduced for the refining industry, focusing on materials resistant to sulfide stress cracking in corrosive petroleum refining environments. That same year, ISO adopted MR0175 as ISO 15156.

ASTM A105N NACE MR0175-ISO 15156 SOUR 31076 Flanges

NACE MR0175/ISO 15156 is structured into three parts:
— Part 1: Outlines general principles for selecting crack-resistant materials
— Part 2: Discusses crack-resistant carbon and low-alloy steels, and the use of cast irons
— Part 3: Covers crack-resistant corrosion-resistant alloys (CRAs) and other alloys

The H2S threshold limits are determined based on operator experience and laboratory assessments. The document undergoes continuous refinement by incorporating new alloys and adjusting threshold limits. The definition of threshold limits varies significantly among different alloys or alloy families and the time of requirement addition or revision. Some factors considered in setting H2S threshold limits include CO2, chlorides, pH, temperature, hardness, and yield strength. MR0175 offers guidance on material selection and specification when exceeding H2S thresholds, enabling fit-for-purpose testing to qualify materials for specific applications. Additionally, MR0175 provides application-specific limits.

NACE MR0175/ISO 15156 specifically addresses material resistance to environmental cracking caused by H2S, excluding concerns like general corrosion or localized corrosion such as pitting or crevice corrosion. It does not serve as a material specification regarding minimum mechanical properties, manufacturing processes, or quality control requirements like microstructure and non-destructive examination. Simply meeting NACE standards does not guarantee material suitability for service; additional material specifications like API 5CRA/ISO 13680 are necessary to address mechanical properties and quality requirements.

Our ASTM A105N NACE MR0175-ISO 15156 SOUR 31076 Flanges

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