Study On Insulation Materials Used For Directly Buried Steam Pipeline Fixing Bracket

The heat insulation material used for directly buried steam pipeline fixing bracket is asbestos rubber mat, due to the water absorption and poisonous of asbestos and rubber’s aging as well as the "thermal bridge effect" formed between steel tube and steel protecting tube.They all increase heat loss, so we need to find a kind of high temperature resistant and high strength heat insulation material to instead of asbestos rubber mat and solve the "thermal bridge effect".This paper adopts the pultrusion process, with epoxy and phenolic resin as matrix and glass fiber as reinforcing material to prepare composite materials.Using the plasma spraying technology on20steel substrate to prepare of ceramic coating.Using scanning electron microscope, tensile fracture morphology of the composites were observed;With SEM, EDS, X-ray diffractometer, the characterization of the coating is tested and analyzed.The composite’s thermal, mechanical, thermal insulation performance and the alumina ceramic coating’s heat insulation performance are tested.The thickness of thermal baffle made of thermal insulation material is calculated.The main draw the conclusion is following:(1) The expansion coefficient of EP composite and PF composite gets bigger with the increasing temperature from60℃to350℃, but both in the standard range. The heat resistance of EP composites is better than that of PF composites. The thermal conductivity of the EP composite materials decreases with the addition of microporous CaSiO3. The thermal conductivity of the EP composite materials containing15%microporous CaSiO3is minimum. Weightlessness rate of EP and PF composite materials is within2%under200℃.(2) The EP and glass fiber bonds more closely than PF.The tensile and compressive strength of EP composites are higher than the PF composites. Two kinds of composite material’s tensile and compressive strength are diminishing with the increase of temperature. With the increase of the content of microporous CaSiO3, the tensile and compressive strength of EP matrix composites are reduced. The shear strength of the EP composite material along the fiber direction is smaller than the perpendicular direction.(3) The thickness of plasma spraying ceramic coating is about400μm and the transition layer’s thickness is about80μm.Organization has a number of holes whose size is10μm～60μm. Coating and20steel substrate bonds well.Coating is mainly composed of Al2O3, SiO2.(4) When the steel plate temperature is150℃,the surface temperature of55mm thick experiment materials outside are less than50℃.In150℃～350℃, the thicker the heat preservation material is, the better the heat insulation effect is. When the furnace’s temperature is350℃, the ceramic coating of0.4mm thickness can reduce the surface temperature of the sample about40℃.(5) When work steel pipe is500mm, outside diameter is1000mm, the size of the composite material thermal cutoff is concluded when the work steel pipe outside surface temperature is150℃～350℃.When coating’s thickness is0.4mm～2mm, the heat insulation effect has a linear relationship with the coating’s thickness.It provides a theoretical basis for the directly buried steam pipeline research.(6) We can spray ceramic coating to the reduce surface temperature of work steel pipe to200℃,and combine with EP composite to solve the problem about heat insulation material used for directly buried steam pipeline fixing bracket.