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.

Steel-reinforced thermoplastic pipe is widely used for water transportation in sour gas fields. However, under the combined effects of corrosive media, internal high pressure, and long-term environmental aging, premature failures such as leakage and bursting often occur. To clarify the failure causes and primary contributing factors of the composite pipes, this study conducted a comprehensive analysis through microscopic morphology examination of different typical failure cases, differential scanning calorimetry, Fourier transform infrared spectroscopy, and mechanical property testing. The main failure mechanisms were investigated, and targeted protective measures are proposed. Key findings reveal that the typical failure modes are ductile cracking, aging-induced brittle cracking, and aging creep cracking. These failures follow a mechanism of degradation of the inner and outer polyethylene protective layers, penetration of the medium and corrosion of the steel wires, reduction in pressure-bearing capacity, and eventual structural damage or leakage propagation through the pipe wall. Notably, oxidation induction time values dropped as low as 1.4–17 min—far below the standard requirement of >20 min—indicating severe antioxidant depletion and material aging. The main controlling factors are poor material quality, external stress or mechanical damage, and long-term aging. The polyethylene used for the inner and outer protective layers is critical to the overall pipe performance; therefore, emphasis should be placed on evaluating its anti-aging properties and on protecting the pipe body during installation to ensure the long-term safety and stable operation of the pipeline system.