The insulation layer is made of rigid polyurethane foam with a density of 60kg/m3 ~ 80kg/m3, which fully fills the gap between the steel pipe and the casing, and has a certain bonding strength, so that the steel tube, the outer pipe and the insulation layer form a solid whole. Polyurethane directly buried insulation pipe foam has good mechanical properties and thermal insulation properties. Usually it can withstand 120 degrees of temperature by modifying or combining with other thermal insulation materials.
1. Anti corrosion coating: protect the outer layer of steel pipe from corrosion and extend the service life of steel pipe.
2. External protection steel pipe: protect the insulation layer from groundwater erosion, support the working pipeline, bear certain external load, and ensure the normal operation of the working pipeline.
3. polyurethane foam layer: ensure the medium temperature and the surface temperature of the outer protective tube are kept normal.
4. barrier and reflective layer: ensure that organic foam material does not enter the inorganic hard and high-temperature resistant layer; reflects part of the heat of the high temperature resistant layer.
5. inorganic hard insulation: high temperature, ensure the interface temperature between the organic insulation layer, ensure that the foam is not carbonized.
6. Drag reduction layer: ensure the free movement of the working steel pipe during thermal expansion and cold contraction.
7. Working steel pipe: ensure the normal flow of conveying medium.
Polyurethane three process foaming polyurethane
The method of dimer
The foaming process of prepolymer method is to make prepolymer from (white material) and (black material), then add water, catalyst, surfactant and other additives into prepolymer, and mix the foaming at high speed. After curing, it can be cured at a certain temperature.
Semia prepolymer
The foaming process of semi prepolymer is to make a part of polyether polyol (white material) and diisocyanate (black material) prepolymer, then add another part of polyether or polyurethane polyol dicyanate ester, water, catalyst, surfactant and other additives, and mix them in high-speed stirring foaming.
One step foaming
Polyether or polyester polyol (white material), polyisocyanate (black material) and other raw materials, water, catalyst, surfactant, foaming agent and other additives are added in one step, and foaming is stirred at high speed.
One step foaming process is widely used. There is also manual foaming process, which is a simple method of zUI, weighing all raw materials accurately, placing them in a container, then mixing immediately, injecting mold or filling the space of foam. Note: Zui of polyisocyanate (black material) must be weighed.
Polyurethane rigid foam is usually room temperature foaming, the molding process is relatively simple. According to the degree of mechanization of construction, it can be divided into manual foaming and mechanical foaming. According to foaming pressure, it can be divided into high-pressure foaming and low pressure foaming. According to the forming method, it can be divided into pouring foam and spray foam.
High temperature prefabricated directly buried insulation pipe mainly consists of four parts:
Working steel pipe: welded steel pipe, seamless steel pipe and double-sided submerged arc spiral welded steel pipe shall be used according to the technical requirements of transmission medium.
Insulation layer: rigid polyurethane foam.
Protective shell: high density polyethylene or glass fiber.
The above is the relevant content introduced by Jinan heat preservation pipe manufacturer. If you want to know more, please visit the website: https://www.sdhpgy.com
