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

One Layer: Working Steel Pipe Layer

Generally, seamless steel pipes, spiral steel pipes, and straight seam steel pipes are selected based on design and customer requirements. The surface of the steel pipes is processed by shot blasting to remove rust, which can reach Sa2 grade according to GB8923-1988 standard, and the surface roughness can reach R=12.5 micrometers according to GB6060.5-88 standard.

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 foaming machine, 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.