Characteristics of submarine pipelines

Haihao Group has recently participated in the supply of submarine pipeline projects and has rich experience in cooperating with this type of project.

Due to different operating environment,submarine pipelines generally vary in diameter from 3 inches (76 mm) for gas lines, to 72 inches (1,800 mm) for high capacity lines. Wall thicknesses typically range from 10 millimetres (0.39 in) to 75 millimetres (3.0 in). The pipe can be designed for fluids at high temperature and pressure. The walls are made from high-yield strength steel, 350-500 MPa weldability being one of the main selection criteria. The structure is often shielded against external corrosion by coatings such as bitumastic or epoxy, supplemented by cathodic protection with sacrificial anodes. Concrete or fiberglass wrapping provides further protection against abrasion. The addition of a concrete coating is also useful to compensate for the pipeline’s negative buoyancy when it carries lower density substances.

submarine pipeline

The pipeline’s inside wall is not coated for petroleum service. But when it carries seawater or corrosive substances, it can be coated with epoxy, polyurethane or polyethylene, it can also be cement-lined. In the petroleum industry, where leaks are unacceptable and the pipelines are subject to internal pressures typically in the order of 10 MPa (1500 psi), the segments are joined by full penetration welds. Mechanical joints are also used. A pig is a standard device in pipeline transport, be it on-land or offshore. It is used to test for hydrostatic pressure, to check for dents and crimps on the sidewalls inside the pipe, and to conduct periodic cleaning and minor repairs.

Before supplying, we actively cooperate with the construction party to make product plans, issue product drawings and send samples according to the characteristics of the local seabed structure. After repeated negotiation, we finally designed products that meet the needs of the team and complete mass production and delivery before the materials are put into use.The final product quality has been well received by users, and it perfectly fits the project schedule. The rich experience in project cooperation allows us to better cooperate with customers to complete various products. If you have questions or needs for pipe fittings, please feel free to contact us, we are very happy to provide you with professional assistance.