The standard “ANSI NACE TM0284 Evaluation of pipeline and pressure vessel steels for resistance to hydrogen-induced cracking,” jointly developed by the American National Standards Institute (ANSI) and the National Association of Corrosion Engineers (NACE), describes a test method for evaluating the resistance of pipeline and pressure vessel steels to hydrogen-induced cracking caused by hydrogen absorption from aqueous sulfide corrosion.
This standard provides details on the size, number, location and orientation of test specimens to be taken from each steel product form (pipes, plates, fittings and flanges).
Specific procedures or requirements are included for testing small diameter (nominal diameter 50 to 150, nominal pipe sizes 2 to 6), thin-walled (wall thickness up to 6 mm), electric-resistance-welded, and seamless pipe. Test specimens from small diameter, thin-walled pipe are tested in the same manner as test specimens from other pipes unless otherwise specified in this standard.
The test method consists of exposing unstressed test specimens to one of three standard test solutions:
These solutions allow testing at different carbon dioxide partial pressures ranging from 0,001 to 1 bar. After a specified time, test specimens are removed and evaluated. While the test length may not be sufficient to induce maximum cracking in any given steel, it has been found to be sufficient for the purpose of this test.
In fitness-for-purpose testing, the test medium and gas partial pressures appropriate to the intended application are selected. The test conditions do not replicate all aspects of service conditions, such as temperature, but they allow adequate discrimination of the suitability of candidate steels. This standard does not include acceptance or rejection criteria.
Each test specimen shall be 100 mm plus or minus 1 mm long and 20 mm plus or minus 1 mm wide. The test specimen thickness shall be the full wall thickness of the pipe, up to a maximum of 30 mm. For wall thicknesses greater than 30 mm, the test specimen thickness shall be the full wall thickness of the pipe or shall be limited to a maximum thickness of 30 mm and shall be stepped along the thickness. A maximum of 1 mm may be removed from each surface (i.e., inside and outside). Test specimen cavities shall not be flattened.
For small-diameter, thin-walled electrically resistance-welded and seamless tubes, the test specimen thickness should be at least 80% of the tube's total wall thickness. In such cases, curved test specimens cut from the tube are tested; the test specimen voids are not straightened.
Three test samples are taken from each test pipe. For seam-welded pipes, test samples are taken from the weld, 90 degrees from the weld, and 180 degrees from the weld. For seamless pipes, test samples are taken 120 degrees apart around the circumference. Test samples are taken from the pipe with the longitudinal axis of the test samples as follows:
Blanks for test specimens may be removed by any suitable method. If a blank is torched, the heat-affected zone of the torched surface shall be completely removed by grinding, cutting, or machining.
The four cut edge surfaces of each test specimen shall be machined or sanded (wet or dry) to an equivalent 320 grit paper coating. The final two passes of the machining shall be such that a maximum of 0,05 mm of material is removed.
Coating of cut edge surfaces is not permitted; all six surfaces must be exposed to the test solution.
All mill scale shall be removed from the interior and exterior surfaces of small-diameter, thin-walled electric resistance-welded and seamless pipe test specimens. Each test specimen shall be machined or ground (wet or dry) to an equivalent 320-grit paper surface or grit-sprayed to a uniform, nearly white metal surface in accordance with applicable NACE standards. The final two passes of the machining shall be such that a maximum of 0,05 mm of material is removed.
Before testing, test samples are degreased with a suitable degreasing solution and rinsed with a suitable solvent, such as acetone. The adequacy of the degreasing method is determined for each batch of test samples by atomizer testing in accordance with ASTM F218 or another equivalent method. The method used shall be reported.
After degreasing, test specimens may be stored in a desiccator and the adequacy of degreasing should be verified using the ASTM F21 standard test or equivalent between removal from the desiccant and exposure to the test solution.
Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the ANSI NACE TM0284 standard, "Evaluation of Pipeline and Pressure Vessel Steels for Resistance to Hydrogen-Induced Cracking."
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
