NACE TM0177-2024 describes laboratory testing of metals for resistance to sulfide stress cracking (SSC) and stress corrosion cracking (SCC) in H2S environments. Revised on September 10, 2024, the supplied 69-page standard includes four test methods and provisions for testing at ambient and non-ambient conditions. This original guide explains method selection, test evidence and procurement considerations. Use the full standard and the governing material qualification or purchasing requirements for test execution and acceptance decisions.
NACE TM0177-2024 PDF — Download Standard
What Is NACE TM0177-2024?
TM0177 provides a common basis for testing stressed metals in aqueous H2S-containing environments so results from different sources can be compared. It describes reagents, specimen properties, test vessels and fixtures, environmental conditions, procedures and reporting. Its intended users include equipment users, manufacturers, fabricators and testing laboratories.
For this document, environmentally assisted cracking (EAC) includes SSC, SCC and hydrogen stress cracking (HSC). Its scope does not establish dedicated evaluation methods for HIC, SOHIC, hydrogen blistering, chloride SCC, pitting or mass-loss corrosion. Those mechanisms require separate assessment where relevant.
Standard at a Glance
| Item | NACE TM0177-2024 |
|---|---|
| Revision date | September 10, 2024 |
| Subject | Laboratory resistance testing for SSC and SCC in H2S environments |
| Methods | A: tensile; B: three-point bent beam; C: C-ring; D: double-cantilever beam |
| General provisions | Sections 1–7 apply across the methods |
| Method-specific sections | Sections 8–11 |
| Conditions | Ambient testing and adaptations for non-ambient temperature and pressure |
| Reporting | Method-specific requirements and recommended material qualification templates |
Methods A, B, C and D Compared
| Method | Specimen / loading approach | Result interpretation |
|---|---|---|
| A — Section 8 | Uniaxial tensile specimen | No-cracking tensile stress for the specified exposure, or failure information |
| B — Section 9 | Three-point bent-beam specimen | Critical stress factor Sc; the statistical characterization differs from a simple tensile-stress result |
| C — Section 10 | C-ring specimen | No-cracking circumferential stress for the specified exposure, or failure information |
| D — Section 11 | Double-cantilever-beam specimen | KISSC threshold stress-intensity result for SSC |
Method selection depends on the product geometry, material condition, orientation, required property and governing specification. The methods can rank materials differently, so their results are not automatically interchangeable. Four-point bend testing is addressed separately by NACE TM0316.
TM0177 vs MR0175 / ISO 15156
NACE MR0175/ISO 15156 establishes principles and requirements for selecting and qualifying materials for defined sour production environments. TM0177 supplies laboratory test methods that can support that qualification or a purchasing test requirement. A report stating only “tested to TM0177” is incomplete evidence of acceptance.
Identify the method, edition, environment, applied stress or loading basis, specimen condition, exposure and acceptance criterion. The qualification framework or purchase specification determines how the results are used. Passing one test condition does not establish suitability for every sour environment or resistance to every corrosion mechanism.
What Changed in the 2024 Revision?
The revision rationale identifies changes to specimen cleaning, test solution definitions and environmental control, non-ambient testing, DCB precracking and fracture-surface interpretation, and reporting. These changes make the edition reference important when comparing test reports.
- Paragraph 4.5 adds cleaning procedures for the individual methods.
- Section 6 clarifies general information and revises solution definitions, deaeration and saturation provisions.
- Section 7 clarifies and standardizes non-ambient testing.
- Section 11 adds detailed precracking provisions and fracture-surface examples.
- Reporting requirements for Methods A–D are revised; recommended MR0175/ISO 15156 material qualification reporting tables move to nonmandatory Appendix D.
- Nonmandatory Appendix E adds DCB precracking recommendations; the former Appendix E becomes Appendix F.
- Appendix G, formerly Appendix D, becomes mandatory and adds a second compliance method.
Appendices A, B and C remain nonmandatory and unchanged according to the revision rationale. Distinguish mandatory provisions from recommended reporting formats when preparing a test instruction.
Test Environment and Specimen Selection
Specimen location and orientation must represent the product feature being assessed. Section 4 highlights variation across a pipe, plate, weld and heat of material. Heat treatment, microstructure, mechanical history and cold work can affect cracking susceptibility; different material conditions must not be treated as equivalent without a justified basis.
Control and document the selected solution, pH, gas environment, temperature, pressure and exposure. Sections 3, 5 and 6 address reagent quality, fixtures and environmental control; Section 7 covers non-ambient conditions. A test environment must be identified in full rather than described only as “sour.”
H2S testing requires a suitably equipped laboratory and appropriate health, safety and environmental controls. This overview is not an operating procedure for handling H2S or running a pressure test.
Exposure Time and Result Interpretation
Section 1 describes characterization over 720 hours for Methods A and C, and the statistical critical stress factor for Method B over 720 hours. Method D provides an average KISSC threshold stress-intensity result. Do not apply a single exposure statement or acceptance calculation indiscriminately across all methods.
The standard notes that CRAs can require additional exposure time and points to ISO 15156-3:2020 Technical Circular 2:2022 for further guidance. A 720-hour test is therefore not a universal demonstration of CRA suitability.
Section 2 discusses reproducibility and interpretation limits. Temperature, anisotropy, galvanic coupling, material inhomogeneity and statistical scatter can change results. Longer exposure or additional specimens may produce lower apparent no-cracking thresholds. Accelerated environments can also cause damage that differs from field behavior. Report the observations and apply the agreed acceptance basis rather than converting a laboratory result directly into a universal service rating.
Duplex Stainless Steel, Nickel Alloys and Welds
For duplex stainless steel and nickel alloys, select the test method and conditions using the relevant material qualification framework, including ISO 15156-3 where applicable. Check actual alloy composition, final heat treatment, strength, hardness, microstructure and manufacturing history.
Galvanic coupling can increase or decrease cracking susceptibility. Test fixtures and any intentional coupling must be considered in the interpretation. An ambient carbon-steel test cannot automatically represent the worst condition for another alloy family.
For welded products, the sampling plan should address the region of interest, including weld metal or heat-affected zones as required by the qualification. Parent-metal evidence does not by itself establish weld performance. Agree specimen location and orientation before manufacture or machining.
Purchasing and Test Report Checklist
A useful order or laboratory instruction should identify:
- NACE TM0177-2024 and the selected Method A, B, C or D.
- The purpose: product acceptance, material qualification, comparison or research.
- The governing product specification, qualification framework and acceptance criteria.
- Material grade, heat identification, product form and final manufacturing condition.
- Specimen number, sampling locations, orientation, dimensions and surface preparation.
- Test solution, gas environment, pH, temperature, pressure and exposure duration.
- Stress or loading basis and relevant measured material properties.
- Failure observations or method-specific calculated results, including the DCB interpretation where applicable.
- Deviations, environmental measurements and traceability to the tested material.
Use the standard’s method-specific reporting requirements and, where appropriate, the Appendix D qualification template. Preserve the limits of the qualification alongside the results.
Frequently Asked Questions
Is TM0177 a material selection standard?
It is a laboratory test-method standard. Material selection and qualification for sour production service are addressed by the applicable MR0175/ISO 15156 framework and project requirements.
Does TM0177 include four-point bend testing?
No. Its bent-beam Method B uses three-point loading. Four-point bend testing is addressed separately by NACE TM0316.
Are Methods A, B, C and D interchangeable?
No. They use different specimen and loading approaches and produce different forms of data. Select the method required by the governing qualification or purchasing specification.
Does a 720-hour pass prove every CRA is suitable?
No. CRAs can need additional exposure, and acceptance depends on the method, tested conditions, material state and applicable qualification requirements.
Does TM0177 establish HIC resistance?
It is not a dedicated HIC test standard. HIC/SOHIC or blistering can occur during exposure and affect interpretation, but require their own assessment where specified.
Can a parent-metal result qualify a weld automatically?
No. Welding changes material condition, and the relevant weld regions and qualification requirements need to be addressed.