Currently, API 5CT P110 and Q125 grades are not suitable for sour-service per ANSI/NACE MR0175 / ISO15156 below 175°F and 225°F, respectively; however, there are indications that the materials can be resistant to sulfide stress cracking (SSC) under certain conditions where a combination of hydrogen sulfide concentration, applied stress, pH, and temperature results in a less severe environment. The primary driver behind the work was to identify an acceptable combination of the above variables that could enable the use of P110 and restricted yield Q125 (Q125RY) grades in mildly sour wells. The scope of work included testing three heats each of grades of seamless P110 and Q125RY casing/coupling stock; the tested heats were received from multiple manufacturers. The P110 materials were evaluated using Method A per NACE TM0177 Standard Test Method at varying temperatures (24°, 40°, 48° and 60°C) and partial pressures/fugacities of hydrogen sulfide (0.14, 0.5, and 1 psi); all materials were tested via NACE TM0177 Method D at ambient conditions and 0.14 psi of H2S partial pressure to establish resistance to sulfide stress cracking (SSC) initiation and crack propagation.