NACE Tests NACE STANDARD TENSILE TEST (Proof Ring Test) The NACE Standard Tensile Test provides for evaluating metals for EC resistance under uniaxial tensile loading. It offers a simple un-notched test specimen with a well-defined stress state. EC susceptibility is usually determined by time-to-failure. Tensile test specimens loaded to a particular stress level give a failure/ no-failure test results. When multiple test specimens are tested at varying stress levels, an apparent threshold stress for EC can be obtained. Six samples are loaded at a time for test duration of 720 hours. NACE STANDARD BEND BEAM TEST The NACE Standard Bend Beam Test provides for testing carbon and low-alloy steels subjected to tensile stress to evaluate resistance to cracking failure in low pH aqueous environment containing H2S. It evaluates EC susceptibility of these materials in the presence of a stress concentration. The compact size of the bend beam test specimen facilitates testing small, localized areas and thin materials. Bend Beam Test specimens loaded to a particular deflection give a failure/ no-failure test results. When testing multiple test specimens at varying deflections, a statistically based critical stress factor (Sc) for a 50% probability of failure can be obtained. NaCl is not added to the test solution for this test method. Laboratory test data for carbon and low-alloy steel have been found to correlate with field data. HYDROGEN INDUCED CRACKING as per ANSI/ NACE Standard TM0284-2003 Absorption of hydrogen generated by corrosion of steel in a wet hydrogen sulfide (H2S) environment can have several effects that depend on the properties of the steel, the characteristics of the environment and other variables. One adverse effect observed in pipeline and pressure vessel steels is the development of cracks along the rolling direction of the steel. Cracks on one plane tend to link up with the cracks on adjacent planes to form steps across the thickness. The cracks can reduce the effective wall thickness until the pipe or pressure vessel becomes overstressed and ruptures. Cracking is sometimes accompanied by surface blistering.