NACE - TM0177
Laboratory Testing of Metals for Resistance to Specific Forms of Environmental Cracking in H2S Environments
|Publication Date:||1 January 1996|
This standard covers the testing of metals subjected to tensile stresses for resistance to cracking failure in low-pH aqueous environments containing H2S. Carbon and lowalloy steels are commonly tested for EC resistance at room temperature where SSC susceptibility is typically high. For other types of alloys the correlation of EC susceptibility with temperature is more complicated.
This standard describes the reagents, test specimens, and equipment to use, discusses base material and test specimen properties, and specifies the test procedures to follow. This standard describes four test methods:
Method A - Standard Tensile Test
Method B - Standard Bent-Beam Test
Method C - Standard C-Ring Test
Method D - Standard Double-Cantilever-Be
Sections 1 through 7 of this standard give general comments that apply to all four test methods. Sections 8 through 11 indicate the test method to follow for each iype of test specimen. General guidelines to help to determine the aptness of each test method are given at the beginning of each test method description (Sections 8 through 11). Reporting of the test results is also discussed.
Metals can be tested for resistance to EC at temperatures and pressures that are either ambient (atmospheric) or elevated.
For testing at ambient conditions, the test procedures can be summarized as follows: Stressed test specimens are immersed in acidified aqueous environments containing H2S. Applied loads at convenient increments can be used to obtain EC data.
For testing at temperatures higher than 27°C (8OoF), at either atmospheric or elevated pressure, Section 7 describes an altemative test technique. All methods (A, B, C, and D) are adaptable to this technique.
Safety Precautions: H2S is an extremely toxic gas that must be handled with care. (See Appendix A.)