Appendix 2 - Additional Compatibility Test Requirements for Ammonia Service
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1599/Rev.2 - Revised Guidelines on the Application of High Manganese Austenitic Steel for Cryogenic Service (MSC.1/CIRC.1599/REV.1) - (15 June 2022) - Appendix 2 - Additional Compatibility Test Requirements for Ammonia Service

Appendix 2 - Additional Compatibility Test Requirements for Ammonia Service

The test should be carried out in accordance with a recognized standard such as ASTM B858. This standard is applicable to copper alloys and not specifically to high manganese austenitic steel. Consequently, the following additional non-standard test should be performed:

  • .1 Specimens should be prepared in accordance with standards ISO 7539-2 and ISO 16540. The specimens should be bent, prior to testing, using the four points bending test under constant strain. The total maximum strain of the sample should be equal to the yield strength of the material at atmospheric temperature. Strain gauges should be applied to measure the strain applied. In the case of welded specimens, strain gauges should be applied to each side of the welded joint. The sample should be constrained to maintain its form during testing.

  • .2 Two specimens (one welded and one base metal) should each be immersed in the following four ammonia environments for a period of 30 days:

    • .1 liquid phase ammonia environments, obtained by cooling of ammonia below liquefaction temperature with the following liquid ammonia compositions:

      • .1 0.1% weight of water and 2.5 ppm of oxygen; and

      • .2 2.5 ppm of oxygen.

    • .2 gas phase ammonia environments, at ambient temperature and atmospheric pressure with the following compositions:

      • .1 pure ammonia; and

      • .2 0.9% volume of oxygen and 99.1% volume of ammonia.

  • Stress corrosion cracking tests should be performed in agreement with requirements of standards ISO 7539 and ISO 16540.

  • .3 Test report should provide all procedures, set up data, examinations, information about the environment, in agreement with standard ISO 16540 and include:

    • .1 the orientation, types and dimensions of specimens;

    • .2 four points bending test set up data;

    • .3 target stress and applied deflection;

    • .4 strain measurement procedures;

    • .5 loading procedures; and

    • .6 test environment.

Test acceptance criteria

After immersion, all specimens should be examined for stress corrosion cracking under an optical microscope with proper magnification. The location and the number of cracks should be specified, and a dye penetrant test performed to confirm the results as necessary. For welded joints, the location of cracks should be described as located in the base metal, weldment or HAZ. If no superficial crack is observed, a longitudinal cut should be done at two different locations and a cross section examination with proper magnification should be performed. The presence of any corrosion pitting and the maximum depth should be reported. The results should be approved by the Administration.

Parent topic: MSC.1/Circular.1599/Rev.2 - Revised Guidelines on the Application of High Manganese Austenitic Steel for Cryogenic Service (MSC.1/CIRC.1599/REV.1) - (15 June 2022)
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