Cross-Country Gas Pipeline Joint Coating in China

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Project reference basis. Figures and configuration details are reported in the supplied project brief. They are reference values for the stated application, rather than verified acceptance results or a guarantee for another installation. Confirm the source records, material, tooling, operating schedule and test method when assessing a comparable project.

A state-owned natural gas transmission enterprise in Northern China deployed Haifeng’s mobile automated hydraulic polyurea spraying units for the external corrosion protection of a major 1,219 mm diameter cross-country gas pipeline. The project covered critical horizontal directional drilling (HDD) crossings through wetlands and saline-alkali terrain spanning 18 kilometers.

Field application occurred in challenging sub-zero winter conditions with ambient temperatures plummeting to -15°C. Traditional pneumatic spray setups and heat-shrink sleeves previously deployed suffered from thermal dissipation along long lines, creating viscosity imbalances that produced microscopic pinholes and poor interfacial adhesion. These flaws caused widespread failures during mandatory 15 kV high-voltage electrical holiday testing.

Haifeng engineered an all-weather mobile hydraulic spraying package centered on the HF-PIPE1400-HYD. Equipped with 120-meter copper-mesh heated hoses and automated pipe-joint rotary indexing units, the system delivered non-pulsing 21 MPa impingement spraying under strict thermal control, achieving continuous, holiday-free barrier membranes across the entire 18-kilometer crossing section.

Haifeng engineered and deployed a high-mobility, cold-weather field spraying package integrated into all-terrain track vehicles. The steel pipeline joints (OD 1,219 mm) were abrasive-blasted to Sa 2.5 cleanliness and preheated to 55°C using an automated medium-frequency induction induction band.

Chemical streams—amine-terminated polyether curative and polymeric MDI—were pumped from heated 200 L drums into the HF-PIPE1400-HYD hydraulic proportioner. Coaxial double-acting hydraulic cylinders maintained stable fluid delivery at 19.5 MPa, eliminating pressure drops during pump stroke reversals.

The chemical lines were routed through 120 meters of copper-jacketed heated umbilical cables to keep fluid temperatures at 65°C right at the pipe face despite sub-zero outdoor weather. Technicians operated automated circular orbital carriages carrying mechanical-purge impingement spray guns. The carriage executed synchronized rotational passes around each welded girth joint, building a uniform 1.8 mm pure polyurea coating in under 8 minutes per joint without drips or sagging.