~~Oil and gas is increasingly being produced at higher temperatures and/or from deep oil reservoirs that contain high concentrations of chloride H2S and CO2. Commonly materials for service in these wells are qualified for a particular environment using stressed-immersion testing to show the susceptibility to stress corrosion cracking (SCC) and/or sulfide stress cracking (SSC). These qualification tests are commonly performed in simulated field conditions using high pressure sour testing in an autoclave. However there are numerous techniques for charging H2S and CO2 into these exposures. The concentration of these gases is affected by the charging technique and thus the results of a particular qualification test can be influenced by gas charging method.The objective of the present work was to compare the four gas charging methods described by Hausler1 with thermodynamic modeling laboratory experiments and validation of gas concentrations. The discussion will include evaluation of the results versus the experimental recommendations in NACE MR0175 / ISO 15156 and NACE TM0177.REFERENCES1.Methodology for Charging Autoclaves at High Pressures and Temperatures with Acid Gases R.H. Hausler Corrosion Journal – August 1998.2.ANSI/NACE MR0175/ ISO 15156-3 “Petroleum and natural gas industries —Materials for use in H2S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs (corrosion resistant alloys) and other alloys” ANSI/NACE/ISO 2009.3.TM0177-2005 “Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking and Stress Corrosion Cracking in H2S Environments” 2005-12-03