X52, X60, and X65
seamless steel pipes, as high-strength line pipes specified in the API 5L standard, are widely used in long-distance transportation applications such as oil and natural gas. To enhance the corrosion resistance of pipelines in complex environments, external epoxy coating technology has become a key protective measure.
Based on thermosetting epoxy resin, the external epoxy coating is evenly applied to the steel pipe surface via electrostatic spraying or high-pressure airless spraying. After preheating to 220-240°C via medium frequency heating, it melts and solidifies, forming a dense three-dimensional network structure. This coating offers the following key advantages:
- High Adhesion: Bond strengths exceeding 10 MPa are achieved, effectively resisting soil stress, cathodic disbonding, and mechanical damage.
- Chemical Corrosion Resistance: The coating remains stable in corrosive media such as hydrogen sulfide (H₂S) and chloride ions. Experimental data show no significant degradation in impact resistance within a temperature range of -30°C to 100°C, and no corrosion after over 2000 hours of salt spray testing. - Long life: In the West-East Gas Pipeline III project, X60 seamless pipes combined with external epoxy coatings have been laid for over 5,000 kilometers, achieving a 99.3% coating integrity rate over 20 years of service, significantly extending the pipeline's service life.
The external epoxy coating's formulation and process can be flexibly adjusted to suit different operating conditions:
- Onshore pipelines: A single-layer FBE (fusion bonded epoxy) coating with a thickness of 300-500μm is used, suitable for normal soil environments.
- Marine environments: A two-layer FBE structure (a standard base layer and a mechanically damage-resistant top layer) has been developed to resist wave erosion and biofouling. Application in oilfield projects has extended the pipeline's lifespan to 50 years.
- Acidic media: For H₂S-containing environments such as the Sichuan-Chongqing shale gas fields, a modified FBE coating with the addition of nano-zinc powder enhances cathodic protection efficiency, enabling stable operation in media with a pH of 4-6.
Threeway Steel is known as a professional supplier engaged in manufacturing and distributing a wide range of steel pipe, and our headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
