Titanium alloys are applied in oil and gas development and transportation to improve conditions because of their high specific strength and corrosion resistance. However, the disadvantage of poor wear resistance has become an obstacle to developing titanium alloys. The friction and wear properties of pure titanium TA3 and titanium alloy TA10 were tested under different loads and different friction forms using a reciprocating friction and wear tester. Moreover, the erosion resistance of pure titanium TA3 and titanium alloy TA10 was studied using a gas–solid erosion tester. The results show that the wear rate of TA3 and titanium alloy TA10 increases with increasing friction load. Under a load of 50 N, the mass losses of TA3 under dry friction and wet friction were 0.0013 g and 0.0045 g, respectively, while the mass losses of TA10 were 0.0033 g and 0.0046 g, respectively. While the load increased to 70 N, the mass loss of TA3 was even greater, reaching 0.0065 g, and the mass loss of TA10 was 0.0058 g. The wear forms of TA3 and TA10 include abrasive wear, adhesive wear and oxidation wear. The joint action of various friction forms leads to the loss of materials. Under the simulated working conditions, the erosion rates of TA3 and TA10 were 1.01 × 10⁻³ g/s and 0.94 × 10⁻³ g/s. The erosion mechanism is the same, including plowing, indentation and cracking.

This study aims to clarify the influence of H₂S concentration and temperature on the sulfide stress corrosion cracking (SSCC) susceptibility of 20# steel weld joints. 20# steel is a commonly selected pipe material for ground gas pipelines, and there is a risk of welds cracking after years of service. The selection of a corrosive environment is based on the working conditions of high-sulfur oil fields on site. Slow strain rate tensile (SSRT) tests were conducted under simulated high-sulfur gathering and transportation conditions across varying temperatures and H₂S concentrations. The mechanical properties, SSCC susceptibility, fracture morphology, and elemental composition of fracture surfaces were systematically analyzed. As H₂S concentration increased (5%, 7.5%, 10%) and temperature decreased (30–60 °C), the elongation after fracture and the reduction in area of 20# steel decreased, while the yield strength and SSCC susceptibility increased. The H₂S concentration range of 0–5% represented a critical sensitivity interval for the material, where elongation after fracture decreased by up to 74%. Within the 5–10% H₂S range, elongation decreased by only 2.11%, indicating a slowing trend of fracture toughness deterioration, though SSCC susceptibility still increased by 12%. Increasing the temperature from 30 °C to 60 °C reduced SSCC susceptibility by approximately 30%, confirming higher susceptibility at lower temperatures. Temperature exerts a lesser influence on material performance than H₂S concentration. Also, 20# steel remains within the SSCC brittle fracture sensitivity zone in sulfur-containing environments, necessitating strict quality control to avoid defects and stress concentrations. In high-sulfur environments (H₂S > 5%), further increases in H₂S concentration have a diminished effect on cracking susceptibility.

To investigate the corrosion failure of a reducing tee at a shale gas station, a failure analysis was carried out. The failed tee was made of L245N steel, with a large-diameter branch of DN 80 and a small-diameter branch of DN 25. The DN 80 branch conveyed shale gas, while the DN 25 branch served as a vent and remained closed. The tee was after approximately 20 months of service. By means of macroscopic observation, transported medium analysis, chemical composition testing of the pipe fitting, hardness testing, metallographic structure examination, and analysis of the composition and morphology of corrosion products, the corrosion failure mechanism was identified. The chemical composition and mechanical properties of the tee met the standard requirements, the inclusion content was low, and the microstructure was normal. A substantial quantity of loose, lamellar and block-like corrosion products had formed at and around the perforation. The corrosion pit regions were mainly composed of Fe, C, O, and a small amount of S. The corroded areas exhibited pitting, ring-like corrosion, and mesa attack. The corrosion products were predominantly FeCO₃, with a small amount of FeS. Comprehensive analysis indicates that the synergistic corrosion effect of carbon dioxide (CO₂) and sulfate-reducing bacteria (SRB) is the root cause of the corrosion perforation of the tee.