Thread Content
Combined with the relevant background of sulfide stress cracking in oil and gas fields, targeted control methods can be implemented from the four dimensions of materials, processes, environment, and detection, covering the prevention and control needs of the entire project process.: Material selection and composition control strictly follow the NACE MR0175/ISO 15156 standard, using special sulfur-resistant steel, and controlling the material hardness to ≤22HRC (carbon steel weld hardness ≤HB200) ； Reduce the proportion of harmful elements such as C, Mn, S, and P in steel, add appropriate amounts of Cr, Mo, Ti and other elements to optimize the cracking resistance, and give priority to tempered sorbite-type microstructures with better SSC resistance. The welding and stress control process eliminates residual tensile stress generated by welding and cold working through post-weld heat treatment (PWHT) ； Use the welding process specified in NACE SP0472 to control the hardness of the weld and heat-affected zone to not exceed the standard. If necessary, use cooling time control, tempering weld bead and other processes to avoid the occurrence of hardened and brittle structures. Optimize and adjust the service environment by adding amine corrosion inhibitors to the medium to maintain the pH value of the system stably in the range of 9 to 11 and inhibit the electrochemical hydrogen evolution reaction of H₂S ； At the same time, the content of impurities such as O₂ and Cl⁻ in the medium that accelerate corrosion is controlled to reduce the rate of hydrogen atoms penetrating into the steel. Preliminary inspection and risk verification adopt the tensile load test and other methods in the NACE TM0177 (corresponding to domestic GB/T 4157) standard to conduct anti-SSC performance verification of incoming pipes and welding materials, check unqualified components in advance, and avoid the risk of cracking from the source.