REFINERY
New NACE Standard MR0103
NACE MR0103 is a new standard entitled "Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments." Think of it as "NACE MR0175 for petroleum refineries." NACE MR0175 was originally created to cover sulfide stress cracking in the oil and gas production industry. Refineries and other industries were outside of MR0175's scope.
Even so, refineries sometimes referred to MR0175 because it was the only standard in existence that listed acceptable materials and material conditions for resistance to sulfide stress cracking (SSC). During the recent MR0175 revision process-which expanded the scope of MR0175 to cover chloride stress corrosion cracking (SCC) in addition to sulfide stress cracking, it became apparent that MR0175 would no longer be a suitable document for refinery use. The main issue was the temperature limits that would be imposed on austenitic stainless steels to prevent chloride SCC. Refinery applications are typically low chloride, so chloride SCC is not a primary issue. This precipitated the development of a new standard to directly serve the needs of the refining industry.
In general, MR0103 was created by "borrowing" information from MR0175-2002 and the proposed MR0175 rewrite (before it was approved as MR0175-2003), modifying requirements in some instances to better fit the needs of the refining industry, and adding information that was specific to refining. The resulting standard, MR0103-2003, was released in April 2003, shortly after the release of MR0175-2003. The 2003 revision is still current.
Differences between MR0103 and MR0175
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MR0103 includes different guidelines than MR0175 for determining if an environment is "sour," because the sour environments in refineries differ quite significantly from those in oil and gas production. The standard explicitly states it is the user's responsibility to determine if the environment is sour, based upon the guidelines in the document, on plant experience, or on risk-based analysis, and to specify if equipment must meet the MR0103 material requirements.
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Because MR0103 only covers SSC, it does not include environmental restrictions (i.e., temperature limits, chloride limits, pH, etc.) on materials. Although listed materials display varying degrees of resistance to SSC, no attempt is made to rank the materials.
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Materials and/or material conditions are included in MR0103 that are not listed in previous and/or current versions of MR0175, and vice versa.
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Because welding is prevalent in refinery piping and equipment, extra emphasis is placed upon welding controls in several material groups, most notably the carbon steels.
