Details of SSAW steel pipe for drainage application

The drainpipe typically uses SSAW (Spiral Submerged Arc Welded) steel pipe, which is manufactured using the submerged arc welding method. The spiral weld creates a continuous seam, which helps distribute the pressure from the liquid inside the pipe evenly across the pipe's surface, enhancing the strength of the SSAW steel pipe. In contrast, if straight seam steel pipes (such as ERW pipes) were used, larger steel plates would be required to form the pipe, complicating the manufacturing process and increasing costs.

In the production of SSAW steel pipes, the stability of the forming process is critical to ensuring welding quality. Consistent forming quality is essential for achieving good weld penetration and appearance. During the welding process, the gap between the steel plate joints must remain uniform, and welding parameters should be adjusted according to variations in the gap to ensure optimal weld quality.

To produce high-quality SSAW steel pipes for drainage, the focus is on improving the plasticity and toughness of the pipes, enhancing the cleanliness of the molten steel, reducing harmful inclusions, and improving the overall steel quality. The production process also involves adopting a reasonable cooling system to prevent internal cracking and ensure the pipe’s quality. Additionally, careful control of the heating temperature during production is necessary, with the best heating temperature determined by thermoplastic curve measurements. Sufficient heat preservation time is also required when heating the tube billet to reduce deformation resistance and improve the plastic toughness of the thick-walled SSAW pipe.

Corrosion Protection of SSAW Steel Pipes for Drainage

Corrosion protection for SSAW steel pipes used in drainage typically starts with suppression during the production process. However, when materials with negative electrochemical potential are connected to the SSAW pipe, the typical corrosion protection mechanisms may not be sufficient. Therefore, both anti-corrosion coatings and sacrificial anode protection are commonly used for main pipelines, such as gas pipelines in urban areas. For lower-pressure non-main pipelines, the use of anti-corrosion coatings alone is usually adequate.

Currently, common external anti-corrosion layers for buried gas pipelines include a three-layer PE composite structure, Powdered Epoxy Resin (FBE), Coal Tar Enamel, and other coatings such as epoxy coal tar pitch and PE tape. It is important to note that sacrificial anode protection is not recommended for pipelines in areas with high soil resistance or those that are flooded. The choice of anti-corrosion method should be based on the pipeline's pressure and the specific environmental conditions, as different methods vary in both cost and effectiveness.