Study on manufacturing techniques and material selection for pipeline headers in oil and gas transportation

Based on the thermoforming process characteristics of headers for oil and gas pipelines, the effects of heating temperature and cooling rate on the microstructure and mechanical properties of commonly used steels (X80, X70, X60, and Q345R) were systematically investigated through thermal simulation tests, mechanical property evaluations, and microstructural characterization. The results indicate that thermo mechanically controlled processed (TMCP) ultra-low carbon micro alloyed steels (X60, X70, and X80) exhibit inferior thermal stability during secondary hot working compared to Q345R steel. Improper hot working processes can eliminate the beneficial effects of TMCP, leading to significant deterioration in strength and toughness. Consequently, conventional manufacturing methods involving flame heating and branch forming by hot drawing from straight pipe sections are not recommended. For thick-walled headers fabricated from TMCP air-cooled steels, the preferred manufacturing approach involves hot-extruded tee joints welded to pipe segments.