New stainless steel seamless pipeline

The new line with martensitic stainless steel seamless pipeline KL-HP12CR has excellent weldability, mechanical properties and corrosion resistance. Its weldability is improved by reducing its carbon and nitrogen content. Reducing the carbon content also significantly improves the resistance to carbon dioxide corrosion, with a corrosion rate of less than 0.127 mm / a in a carbon dioxide environment at temperatures as high as 160 °C. and 2.0 MPa. Sulfide stress cracking (SSC) due to the addition of molybdenum. This new seamless pipeline can be used in hydrogen sulfide environments at pH 4.0 and 0.001 MPa. The strength of this pipe is X80 grade, with adequate low temperature toughness when used in pipelines. Postweld heat treatment for several minutes, reducing the carbon content and adding titanium can effectively prevent the occurrence of intergranular stress corrosion cracking (IGSCC) in the HAZ. The pipe is expected to be further used to deliver liquids containing corrosive gases such as carbon dioxide, a cost-effective, high-life, low-cost material.

Concerns over the decline in oil resources are growing, and the temperatures and pressures in the wells and gas wells currently being mined are reaching unprecedented levels, with the liquids being mined generally containing carbon dioxide, resulting in more corrosion. Therefore, to prevent the flowline and collection pipeline from being corroded by carbon dioxide, it is extremely important to transport the liquid before removing corrosive substances and water. In addition, these liquids usually contain trace amounts of hydrogen sulfide, and therefore need to prevent chloride stress cracking. In this corrosive environment, for the carbon steel pipe material, the traditional anti-corrosion method is to inject liquid into the rust inhibitor, anti-rust agent to prevent corrosion. However, this increases the cost of production, especially offshore pipelines, so rust inhibitors are less commonly used, especially considering life cycle costs. Another reason not to use rust inhibitors is the fear of contamination from spills. Therefore, there is a need for an economical and economical material that does not require the use of a rust inhibitor. Existing pipeline corrosion-resistant alloys, including duplex stainless steel, but the disadvantage is the high cost of materials. In contrast, martensitic stainless steels generally have poor weldability and require preheating and longer post-weld heat treatment. Therefore, considering the pipe laying efficiency, martensitic stainless steel is rarely used in pipelines. However, martensitic stainless steels have adequate resistance to carbon dioxide corrosion and are cheaper than duplex stainless steels.