Comparison of NACE MR0175 and NACE MR0103
Both NACE MR0175/ISO 15156 and NACE MR0103/ISO 17945 are standards that specify requirements for metallic materials resistant to sulfide stress cracking (SSC) in sour environments containing hydrogen sulfide (H₂S) and liquid water. However, they serve different segments of the oil and gas industry, and their technical requirements differ accordingly.
Similarities
| Aspect | Requirement |
|---|---|
| Primary Concern | Both address sulfide stress cracking (SSC) in H₂S-containing environments |
| Carbon Steel Hardness | Both require maximum hardness of ≤22 HRC for carbon steel base metal and weldments |
| Material Coverage | Both cover carbon steels, low-alloy steels, stainless steels, duplex stainless steel, and nickel alloy |
| User Responsibility | Both standards state that the end user is responsible for determining material suitability for their specific application |
| ISO Integration | Both have been integrated into ISO standards (MR0175 → ISO 15156; MR0103 → ISO 17945) |
Differences
| Comparison Dimension | NACE MR0175/ISO 15156 | NACE MR0103/ISO 17945 |
|---|---|---|
| Applicable Industry Sector | Upstream (oil & gas production, drilling, wellhead equipment, gathering systems) | Downstream (petroleum refineries, chemical processing, hydroprocessing units) |
| Environmental Application | Offshore and onshore production facilities | Onshore refinery process plants |
| Corrosion Types Covered | SSC + Chloride Stress Corrosion Cracking (Cl-SCC) | SSC only (does not address chloride-induced cracking) |
| Material Qualification Approach | Environment-based approach: materials qualified within specific H₂S partial pressure, temperature, Cl⁻ concentration limits | Binary pass/fail approach: materials are either “acceptable” or “not acceptable” |
| Austenitic Stainless Steel Welding Hardness Survey | Required for WPQ (Vickers 10kg or Rockwell 15N scale) | Not required for austenitic stainless steel |
| Duplex Stainless Steel Ferrite Requirements | Base metal: 35-65% ferrite; Weld deposit: 30-70% ferrite (no max hardness) | Base metal: 35-65% ferrite; Weld deposit & HAZ: 35-65% ferrite; Plus max 28 HRC hardness requirement |
| Carbon Steel Welding Reference | No specific referenced practice for carbon steel welding controls | Explicitly references NACE SP0472 for carbon steel welding control |
| ASTM A105 Forgings | Allowed with 187 HBW max (as-hot-forged condition permitted) | Requires subsequent heat treatment (annealing, normalizing, etc.) |
| ASTM A216 WCC Carbon Steel | Hardness ≤22 HRC requirement applies | No explicit max hardness requirement for base metal |
| Bolting Materials | ASTM A193 B7 bolts prohibited (use B7M or other SSC-resistant materials) | Less restrictive bolting requirements (refinery-specific) |
| Legal Status | Mandatory in some US states; legally required for certain applications | Industry-recommended standard; no legal enforceability |
| Year of ISO Merger | 2003 (merged into ISO 15156) | 2015 (merged into ISO 17945) |
Key Technical Highlights
1. Hardness and Welding Qualification
- MR0175/ISO 15156 requires weld procedure qualification (WPQ) hardness surveys for carbon steels, low-alloy steels, martensitic stainless steels, austenitic stainless steels, and precipitation-hardenable alloys. For duplex stainless steels, metallographic ferrite measurements and microstructural examination at 400X are required instead of hardness surveys.
- MR0103 also requires WPQ hardness surveys using Vickers 10kg load for carbon steels, alloy steels, martensitic stainless steels, duplex stainless steels, and precipitation-hardenable alloys. However, for duplex stainless steels, ferrite measurements are required in both weld deposit AND HAZ, with a maximum hardness of 28 HRC.
2. Material Certification Interchangeability
A material certified to one standard cannot automatically be considered compliant with the other standard. Specific factors to consider include:
- Heat treatment condition (e.g., ASTM A105 requires additional heat treatment for MR0103)
- Weld repair procedures and qualification testing
- Ferrite content requirements for duplex materials
- Hardness testing requirements for specific alloy grades
3. Corrosion Mechanism Scope
MR0175 explicitly addresses chloride stress corrosion cracking (Cl-SCC) in addition to SSC, recognizing the combined effects of chlorides, temperature, and pH in upstream production environments. MR0103 focuses exclusively on SSC, which is the predominant concern in refinery environments where chloride levels are typically controlled.
Summary Table: Quick Reference
| Feature | MR0175/ISO 15156 | MR0103/ISO 17945 |
|---|---|---|
| Industry | Oil & Gas Production (Upstream) | Petroleum Refining (Downstream) |
| Environment | Offshore/onshore production | Onshore refinery process |
| Corrosion Types | SSC + Cl-SCC | SSC only |
| Qualification | Environment-based limits | Binary (pass/fail) |
| Austenitic SS Welding | Requires hardness survey | No hardness survey required |
| Duplex Stainless Steel Hardness | No max hardness specified | ≤28 HRC required |
| Duplex Ferrite (Weld) | 30-70% | 35-65% |
| Reference Practice | None specified for CS welding | NACE SP0472 |
| Legal Status | Mandatory in some regions | Recommended only |
Practical Application Guidance
- Choose MR0175/ISO 15156 for: Oil and gas wells, flow lines, gathering systems, offshore platforms, and any upstream production equipment
- Choose MR0103/ISO 17945 for: Refinery process units, hydroprocessing equipment, amine treating units, and other downstream facilities handling H₂S-containing hydrocarbon or aqueous streams
