Polyurethane thermal insulation pipes are structured in three layers from the inside out:

One Layer: Working Steel Pipe Layer

In accordance with design and customer requirements, seamless steel pipes, spiral steel pipes, and straight seam steel pipes are generally selected. After being treated with shot blasting to remove rust, the steel pipes can achieve a rust removal level of Sa2 as per GB8923-1988 standards, and the surface roughness can reach R=12.5 micrometers as per GB6060.5-88 standards.

Second Layer: Polyurethane Insulation Layer

Formed by injecting the liquid raw material of rigid polyurethane foam plastic into the cavity between the steel pipe and the outer sheath with a high-pressure foam machine in one go, commonly known as "foam-in-place pipe".

Three Layers: High-Density Polyethylene Protective Layer

Preformed black or yellow polyethylene plastic pipes with specified wall thickness. Their functions include: 1) protecting the polyurethane insulation layer from mechanical damage by hard objects, and 2) corrosion and water resistance.