Evaluation of Pipeline and Pressure Vessel Steels for Resistance to Hydrogen-Induced Cracking
|Publication Date:||22 March 2016|
This standard establishes a test method for evaluating the resistance of pipeline and pressure vessel steels to HIC caused by hydrogen absorption from aqueous sulfide corrosion.
Details are provided on the size, number, location, and orientation of test specimens to be taken from each steel product form-pipes, plates, fittings, and flanges.
Special procedures or requirements for testing small-diameter (nominal diameter [DN] 50 through 150, nominal pipe size [NPS] 2 through 6), thin-wall (up to 6 mm [0.2 in] wall thickness), electric-resistance welded (ERW) and seamless pipes are included. The test specimens taken from small-diameter, thin-wall pipes shall be tested in the same manner as the test specimens taken from other pipes except as otherwise stated in this standard.
The test method consists of exposing unstressed test specimens to one of the three standard test solutions-Test Solution A, an acidified brine solution consisting of sodium chloride (NaCl) and acetic acid (CH3COOH) dissolved in distilled or deionized water saturated with H2S at ambient temperature and pressure; or Test Solution B, a synthetic seawater solution saturated with H2S at ambient temperature and pressure; or Test Solution C, a buffered solution consisting of sodium chloride (NaCl) and sodium acetate (CH3COONa) dissolved in distilled or deionized water saturated with gas containing mixtures of H2S and CO2 at ambient temperature and pressure enabling testing to be conducted at different H2S partial pressures in the range 0.001 to 1 bar. After a specified time, the test specimens are removed and evaluated.
NOTE: The length of the test may not be sufficient to develop maximum cracking in any given steel, but has been found to be adequate for the purpose of this test.
In Fitness-for-Purpose testing, the test environment and partial pressures of gases appropriate to the intended application are selected.
NOTE: The test conditions do not duplicate all aspects of service conditions, for example temperature, but will allow sufficient discrimination of the applicability of candidate steels. See Paragraph 8.1.5 and associated notes.
This standard does not include acceptance or rejection criteria; however, guidance is provided in NACE MR0175/ISO(1) 15156,5 Part 2, Section 8 and Annex B of EFC(2) 16.6
For additional information, the presence or absence of HIC in the exposed specimens may be evaluated by automated ultrasonic testing prior to metallographic sectioning and examination. A procedure is provided in Appendix A (nonmandatory).
(1) International Organization for Standardization (ISO), Chemin de Blandonnet 8. Case Postale 401, 1214 Vermier, Geneva, Switzerland.
(2) European Federation of Corrosion (EFC), 1 Carlton House Terrace, London, SW1Y 5DB, U.K.