Understanding the Use of Polyurethane Foamed Insulation Pipe
In order to increase the heat dissipation of pipeline to soil, an insulating composite layer is added to the pipeline interior in small diameter heat transfer crude oil or heating pipeline. The commonly used thermal insulation material is rigid polyurethane foam with a temperature range of -185 to 120 degrees C. The material is soft. In order to improve its strength, a layer of high density polyethylene (HDPE) is applied to the outer side of the insulating layer to form a composite structure so as to avoid the infiltration of groundwater into the insulating layer.
High-pressure polyurethane foaming equipment is used to stop shot blasting on the surface of steel pipe and corona treatment on the inner and outer surface of external maintenance pipe to improve the bonding function of insulation pipe. The insulation material is rigid polyurethane foam. The density is 60kg / m3 to 80kg / m3, filling the gap between the steel tube and the sleeve and having a certain bonding strength, which makes the steel tube, shell and insulation layer. Construct a solid whole. Polyurethane foam has good mechanical function and thermal insulation function. It usually accepts a temperature of 120 degrees C. After modification or combination with other insulation data, it can withstand 180 C temperature.
Prefabricated polyurethane insulating steel pipes are divided into three layers from inside to outside.
Layer 1: Task Steel Tube Layer
According to the design and customer requirements, seamless steel pipe, spiral steel pipe and straight seam steel pipe are usually used. After primary shot peening treatment, according to GB/T8923-1988 specification, the steel tube rust removal grade reaches Sa2 grade, and the surface roughness in GB6060.5-88 specification can reach R = 12.5 micron.
Second layer: polyurethane insulation layer:
The high pressure foaming machine is used to inject rigid polyurethane foam material into the cavity formed between the steel pipe and the outer sheath, which is usually called "tube foaming".
Layer 3: High Density Polyethylene Maintenance Layer:
The preform is a black or yellow polyethylene plastic pipe with a certain wall thickness. Polyethylene is odorless, non-toxic, waxy and has excellent high temperature resistance. It can be used at high temperatures ranging from - 70 to - 100 degrees C. It has good chemical fluctuation and resistance to a large number of acids and bases (oxidation resistance). Acids) are insoluble in ordinary solvents at room temperature and have low water absorption, but because they are linear molecules, they can be slowly dissolved in some inorganic solvents, do not swell, and have excellent electrical insulation function. Its function is to maintain polyurethane insulation layer from mechanical hard damage, the second is anti-corrosion, waterproof. High density polyethylene foam insulation steel pipe execution: SY/T114-2000 and SY/T115-2001 specification.
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