In recent years, bimetallic composite pipes have gradually become the mainstream pipe material for acid gas field gathering and transportation systems due to their core advantages of strong corrosion resistance, high mechanical strength, superior overall cost, and good construction stability. They have been widely applied in several key acid gas field projects, successfully addressing key development challenges in the industry.
Bimetallic composite pipes are manufactured using advanced metallurgical composite processes. The base layer is made of carbon steel or low-alloy steel, primarily responsible for the structural support, pressure resistance, and impact resistance of the pipeline. The inner lining consists of high-quality corrosion-resistant materials such as stainless steel and nickel-based alloys, forming a dense anti-corrosion barrier. This achieves complementary performance between the load-bearing base layer and the corrosion-resistant coating, precisely adapting to the harsh operating conditions of acid gas fields. Industry data shows that in acidic gas field gathering and transportation media, the synergistic effects of H₂S, CO₂, and highly salinized formation water can cause ordinary carbon steel pipes to corrode at an average annual rate of 0.2-0.5 mm. This typically necessitates replacement every 3-5 years and easily leads to major safety accidents such as sulfide stress corrosion cracking (SSCC), severely impacting normal gas field production.
In contrast, the corrosion-resistant coating of bimetallic composite pipes effectively isolates various corrosive media, strictly controlling the corrosion rate below 0.025 mm/a. This fully meets the NACE MR0175/ISO 15156 acidic environment industry standard, extending service life to 15-20 years, more than three times that of ordinary carbon steel pipes. This significantly reduces pipeline replacement frequency and mitigates safety risks from corrosion at the source.
The outstanding economic efficiency is a key reason for the widespread adoption of bimetallic composite pipes. In the gathering and transportation of acidic gas fields, while pure nickel-based alloy pipes possess excellent corrosion resistance, their high material cost significantly increases engineering investment. In contrast, bimetallic composite pipes use corrosion-resistant alloys only on the inner wall, with a lower-cost carbon steel base layer on the outer layer. The overall cost is only 30%-50% of that of pure corrosion-resistant alloy pipes, and the comprehensive cost of a single well gathering and transportation pipeline can be reduced by 45%-50%. Taking a high-sulfur gas field in northeastern Sichuan as an example, with H₂S content reaching 15% and CO₂ content reaching 8%, the large-scale application of bimetallic composite pipelines has not only significantly reduced material procurement investment but also reduced pipeline maintenance costs and downtime losses by more than 80%, resulting in significant economic benefits.
High strength and high safety are key to ensuring the stable operation of gas fields using bimetallic composite pipes. Its base layer, made of carbon steel, ensures the pipeline possesses excellent pressure resistance and impact resistance, making it suitable for high-pressure gathering and transportation conditions in acidic gas fields. The metallurgical bonding process ensures a bond strength exceeding 210 MPa between the base layer and the cladding, guaranteeing the pipeline will not peel or crack during long-term service, effectively avoiding the interface corrosion risks common in mechanically composite pipes. Simultaneously, the bimetallic composite pipe is compatible with fully automated welding processes, achieving a welding qualification rate of over 90%, increasing construction efficiency by 40% compared to traditional pipe materials, enabling rapid pipeline laying and shortening project cycles.
Currently, bimetallic composite pipes are widely used in several key acidic gas field projects in my country, such as the Sichuan-East Gas Pipeline and the Tarim Oilfield, covering extreme gathering and transportation conditions such as high sulfur content, high temperature, and high pressure. After long-term practical operation testing, no corrosion failure events have occurred, effectively ensuring the safety and stability of the gas field gathering and transportation system. As the development of acidic gas fields in my country progresses to deeper and more complex strata, the continuous optimization of material formulations and composite processes further enhances the corrosion resistance and crack resistance of bimetallic composite pipes, providing reliable material support for the long-term safe development of gas fields.
Industry experts say that the large-scale application of bimetallic composite pipes has not only effectively solved the corrosion problem in the gathering and transportation of acidic gas fields, but also achieved a balance between safety and cost, promoting the transformation of gas field development towards cost reduction, efficiency improvement, green and safe development, providing important technical support for the efficient development of high-sulfur natural gas resources in my country, and helping the energy industry achieve high-quality development.
