First, an analysis of the core advantages of plastic-coated spiral steel pipe
Plastic-coated steel pipe has both the strength of steel pipe and the corrosion resistance of plastic by welding the plastic anti-corrosion layer, becoming the core pipe material of deep-sea oilfields. Its advantages are reflected in three aspects: bearing water pressure of more than 2,000 meters; resisting chloride ion corrosion to extend the service life; smooth inner wall reduces transportation resistance by 20%. These characteristics make it a key material to ensure the safety and efficiency of oil and gas transportation.
Second, a comparison of mainstream types of plastic-coated spiral steel pipe
(1) Polyethylene plastic-coated steel pipe: adopts hot-melt coating process, with outstanding resistance to crude oil corrosion. Mainly used in oil pipelines, its flexible characteristics can buffer the impact of seabed terrain, and the inner wall friction coefficient is 0.01, which improves the transportation efficiency by 15% compared with ordinary steel pipes.
(2) Epoxy resin coated steel pipe: chemical bond bonding technology achieves zero coating shedding, and the seawater corrosion resistance life is up to 30 years. Widely used in water injection systems, with a scale prevention rate of more than 95%, it has maintained stable operation for 10 years in the Gulf of Mexico project.
(3) Polyurea coated steel pipe
The new elastic coating material has a 40% improvement in impact resistance and is suitable for complex seabed terrain. The application case of Tupi Oilfield in Brazil shows that the hydrogen sulfide corrosion resistance is 3 times higher than that of traditional pipes. Although the initial cost is 30% higher, the full-cycle maintenance cost is reduced by 50%.
Third, key factors for selection
(1) Environmental adaptability:
It must meet the following requirements: resistance to 4MPa water pressure, resistance to 2-4℃ low-temperature embrittlement, and resistance to marine biological adhesion. It is recommended to use nano-modified coating to reduce the surface energy to below 20mN/m and reduce 90% biological adhesion.
(2) Medium adaptability
The oil pipeline focuses on hydrogen sulfide corrosion resistance (＞500ppm), the gas pipeline requires a sealing level of ASME B16.34 Class1500, and the water pipeline needs a scale prevention rate of ＞90%.
(3) Engineering parameter matching
The recommended wall thickness formula is: t=(PD)/(2S+0.8P), where the S value for deep-sea environment is ≥480MPa. The diameter selection should control the flow rate in the optimized range of 1.5-3m/s.
Fourth, the quality control system of plastic-coated spiral steel pipes
The GB/T23257-2017 standard is implemented, and the key indicators include: coating thickness (2.0±0.2mm), adhesion (≥10MPa), and no corrosion in the 3000-hour salt spray test. Electromagnetic eddy current detection is used to ensure that the defect detection rate is greater than 99.9%.
Fifth, the technical development trend of plastic-coated spiral steel pipes
Intelligent coating: integrated optical fiber sensor, real-time monitoring of corrosion rate and stress distribution
Environmental protection materials: research and development of bio-based polyurethane coatings, VOC emissions reduced by 70%
Connection technology: The laser welding process improves efficiency by 3 times, and the joint strength reaches 95% of the parent material
Sixth, typical application cases
The North Sea oil field project uses a three-layer PE coating system (epoxy primer + adhesive + polyethylene), which has been running continuously for 8 years at a water depth of 1500 meters and 4℃, with an annual corrosion rate of <0.02mm and a maintenance cycle extended to 5 years.
At present, plastic-coated steel pipe technology has achieved 80% localization of deep-sea pipes, and the market size is expected to reach 20 billion yuan in the next five years. By continuously optimizing coating materials and testing technologies, it will support the development needs of ultra-deepwater oil fields of 1,500-3,000 meters and promote the upgrading of marine engineering equipment.
Post time: Apr-30-2025